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Estimating Premorbid Intelligence among Older Adults: The Utility of the AMNART

Estimating Premorbid Intelligence among Older Adults: The Utility of the AMNART SAGE-Hindawi Access to Research Journal of Aging Research Volume 2011, Article ID 428132, 7 pages doi:10.4061/2011/428132 Research Article Estimating Premorbid Intelligence among Older Adults: The Utility of the AMNART Deborah A. Lowe and Steven A. Rogers Department of Psychology, Westmont College, 955 La Paz Road, Santa Barbara, CA 93108, USA Correspondence should be addressed to Deborah A. Lowe, delowe@westmont.edu Received 7 July 2010; Revised 7 January 2011; Accepted 24 February 2011 Academic Editor: Astrid E. Fletcher Copyright © 2011 D. A. Lowe and S. A. Rogers. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This study examines the utility of the American version of the National Adult Reading Test (AMNART) as a measure of premorbid intelligence for older adults. In a sample of 130 older adults, aged 56 to 104, the AMNART was compared to other tests of premorbid intelligence. The results revealed that AMNART-estimated IQ was significantly higher than other premorbid estimates. Across specific educational groups (i.e., 0–12, 13–16, and 17 or more years of education), AMNART-estimated IQ was inflated relative to all other premorbid estimates. The AMNART also declined as cognitive impairment increased, and there was a significant interaction between aging-related diagnostic group and premorbid estimate. The AMNART may therefore overestimate premorbid ability relative to other premorbid measures, particularly among those with greater cognitive impairment and lower levels of education. These results suggest that the AMNART should be used cautiously among older adults and in conjunction with other estimates of premorbid ability. 1. Estimating Premorbid Intelligence among One approach to assessing premorbid functioning among older adults involves the use of demographic vari- Older Adults: The Utility of the AMNART ables, such as education, sex, handedness, and occupation Considering the rapidly burgeoning older population, in- [1]. This approach can be useful because the data are gained creased attention is being given to an accurate assessment of without lengthy or invasive testing and independent of the older adults’ cognitive and neuropsychological functioning. patient’s current cognitive functioning and therefore remain Part of this process involves obtaining a viable estimate of constant throughout the patient’s adult life without being their premorbid cognitive ability or their expected perfor- affected by any cognitive decline that may occur [2]. The use mance prior to any injury or relative decline in cognitive of demographic variables has been shown in some studies functioning. These premorbid estimates are critical toward to be a good estimate of premorbid intelligence among determining the nature, type, and severity of cognitive healthy controls [3] and has been recommended over other impairment. It is vital when estimating the level of cognitive premorbid estimates for those with Alzheimer’s disease [4]. decline to account for variations in premorbid ability. For Demographic variables have been found in some cases to example, an older adult might be performing in the average improve the accuracy of alternative approaches [5]. However, range relative to his or her peers, but this could be a potential other studies have found that demographic indices involving decline if his or her previous premorbid abilities were in education in particular are not always the most accurate the high average or superior range. It is also important to estimates of premorbid intelligence in normal aging and obtain a premorbid indicator in addition to age-based norms Alzheimer’s disease [6–8], perhaps reflecting the intellectual to account for other factors, such as formal education and development that may occur beyond formal education and occupation, that can contribute to one’s intellectual abilities. continue throughout one’s life. To this end, various approaches have been developed to To address some of the inadequacies in relying solely estimate premorbid intelligence. upon demographic variables, other methods of estimating 2 Journal of Aging Research premorbid intelligence have been suggested, such as the have suggested that the AMNART is a good estimate of Wechsler Adult Intelligence Scale (WAIS) Verbal IQ, Infor- premorbid ability for older adults [31–33]. Pavlik et al. [34] mation, and Vocabulary subtest scores [2, 9]. The most discovered that it was a better premorbid estimate than common approach is the use of word reading tests, which demographic variables, which do not account for intellectual require the participant to verbally pronounce orthograph- development occurring after the completion of one’s formal ically irregular words (e.g., “ache” or “hyperbole”). It is education. However, Gladsjo and colleagues [32]found that assumed that correct pronunciation of these words, which the AMNART’s predictive strength was improved when it was do not follow common English grammatical rules, implies used in conjunction with demographic estimates. prior knowledge of them and therefore a higher premorbid One limitation of the AMNART and similar word reading intelligence [2]. A variety of different word reading tests tests (e.g., NART, NAART) is that they were developed as pre- have been developed, all of which have their own particular morbid estimates in comparison with the WAIS-Revised strengths and weaknesses. (WAIS-R) [35]. AMNART-estimated IQ, as calculated by One of the most common word reading tests is the using Grober and Sliwinski’s regression equation [31], there- National Adult Reading Test (NART) [10, 11], which requires fore predicts premorbid intelligence in comparison with participants to read aloud a list of 50 irregular words. The WAIS-R normative values. Updated regression equations NART appears to be a good estimate for healthy older have not been published to convert AMNART-estimated adults [12] and has been shown to be more resistant to IQ to the newer normative samples of the WAIS-Third the effects of age than the WAIS Vocabulary subtest [13– Edition (WAIS-III) [36] or WAIS-Fourth Edition (WAIS-IV) 15]. Although some researchers have found the NART to [37]. Despite the slightly outdated regression equation, the be a good premorbid estimate among those with dementia AMNART remains a commonly used premorbid estimate, [12, 15–17], others have found that it actually declines in even in conjunction with the WAIS-III [38–42]. In fact, dementia, therefore implying that it is not impervious to even after the publication of the WAIS-III, Schinka and the effects of cognitive impairment [4, 18–20]. Similarly, Vanderploeg [43] still recommend using the AMNART or whilesomeresearchers recommend that the NART should a similar reading test along with demographic information not be used among all adult populations, particularly those (e.g., education level) and select WAIS-III subtests (e.g., In- with organic conditions such as schizophrenia, Korsakoff formation, Vocabulary) when attempting to predict premor- psychosis, or Huntington’s disease [13, 21], others have not bid performance. In the absence of regression equations that found any declines related to these conditions [16]. are updated for WAIS-III or WAIS-IV normative values, the There has also been mixed evidence regarding the utility AMNART is still commonly used as a premorbid estimate. of other word reading tests. Alexander and colleagues [6] In addition, there is insufficient amount of data regarding found that the reading subtest of the Wide Range Achieve- the utility of the AMNART as a premorbid estimate for older ment Test (WRAT) [22] correlated better than demographic adults. Some researchers have argued that the AMNART estimates as a cerebral metabolic measure of premorbid is not an equally valid measure for all populations and cognitive functioning. The North American Adult Reading that it should be used with caution. Boekamp et al. [44] Test (NAART) [23] was also found to be better than found that the AMNART is an overestimate of premorbid education as an estimate of both premorbid intelligence and functioning for those with lower intelligence, which may overall cognitive functioning [7, 9]. Johnstone et al. [24] reflect a floor effect in the regression equation or a third, found that both the WRAT and the NAART were equally mediating variable. In addition, researchers have indicated accurate premorbid estimates for those in the average range that the AMNART significantly declines in dementia and of intelligence, but they were significant overestimates for have recommended against its use among those with those with lower intelligence and underestimates for those cognitive impairment [44–46]. AMNART scores have even with higher intelligence. The Spot-the-Word Test [25], which been found to decline before the diagnosis of dementia is allows participants to choose the correct low-frequency ever made, perhaps suggesting a link to the depletion of English word from a pair of words that includes a nonword, one’s cognitive reserve [47], which is the ability to employ has been found to be a good estimate for older adults with compensatory cognitive strategies and utilize a variety of normal aging and even mild forms of dementia [3], but it neural networks for problem solving. Cognitive reserve is appears to significantly decline in moderate-to-severe forms developed by factors such as education, occupation, and of dementia [26, 27]. The Cambridge Contextual Reading leisure activities and has been shown to act as a buffer Test [28], which places NART words within a semantic against cognitive decline [48–51]. The larger one’s cognitive context, seems to be a better estimate than the NART for reserve, the greater the degree of cognitive deterioration that those who have dementia or lower reading ability [26–30]. must occur before symptoms of dementia or other forms of Another commonly used word reading test, the American cognitive impairment can be detected. Therefore, a decline in version of the NART (AMNART) [31], was developed for AMNART-estimated IQ, even before any formal diagnosis of American English speakers in the USA. Depending on the cognitive impairment, may indicate an insidious depletion of version, this test consists of either 45 or 50 orthographically one’s cognitive reserve. irregular English words, with about half identical to NART In light of the inconclusive data regarding the AMNART, items [2]. During administration, participants are instructed this study examined the utility of AMNART-estimated intel- to pronounce each word out loud, beginning at the top of ligence scores as a measure of premorbid cognitive ability in the list and continuing through the end. Some researchers older adults. This included examining how it compared to Journal of Aging Research 3 Table 1: Correlations between AMNART and variables of interest. other commonly used measures of premorbid intelligence, namely, education, WAIS-III Verbal IQ, and the WAIS- Variable rM SD III Information subtest [2]. To specifically examine the Age −0.01 78.70 10.34 AMNART’s utility among adults with varying levels of Education 0.42 15.62 2.61 education, premorbid measures were examined between MMSE 0.41 27.87 2.67 different educational groupings. Similarly, the AMNART was Premorbid estimate compared to other premorbid estimates among different AMNART z-score — 1.31 0.51 aging-related diagnostic groups to consider its utility as cognitive functioning declines. In light of the limitations VIQ z-score 0.70 0.78 0.97 highlighted by other researchers, it was hypothesized that Information z-score 0.68 0.94 0.99 AMNART-estimated premorbid ability would be signifi- Note. Due to occasional missing data, the smallest sample size was 124. cantly higher than all other premorbid measures and that it p< .001. would be an overestimate of premorbid functioning for those with dementia and lower levels of education. The final results can help clarify and illuminate the most accurate assessment the normative data provided in the administration manual of older adults’ premorbid cognitive and intellectual abilities. [34]. VIQ and AMNART-estimated IQ scores were converted to z-scores based on a mean IQ score of 100 and standard deviation of 15. 2. Method 2.3. Procedure. All participants were given information 2.1. Participants. One hundred and thirty community- about the study, and they provided informed consent. They dwelling older adults (69% female, 95% Caucasian) between were notified that they would have the option for free the ages of 56 and 104 voluntarily completed a comprehen- feedback at a later time. A brief interview was conducted to sive neuropsychological battery (see Table 1 for demographic information). All data were gathered in compliance with gather demographic information, as well as to ascertain the presence of subjective memory complaints and difficulties the Institutional Review Board affiliated with the authors’ with activities of daily living. Participants were then adminis- institution. For purposes of examining measures of premorbid tered a comprehensive neuropsychological battery that took approximately three hours to be completed. ability among older adults at various levels of educational attainment, the sample was divided into three educational groups: those with 0–12 years of education (i.e., high school 2.4. Statistical Analyses. Correlations were conducted or lower; n = 17), those with 13–16 years of education between the AMNART and demographic variables, as well as (i.e., college; n = 68), and those with 17 or more years of between the AMNART and all other estimates of premorbid education (i.e., graduate school; n = 45). functioning (i.e., WAIS-III VIQ and Information). To Participants were classified as having normal aging (n = explore differences in means between the AMNART and 35), age-associated memory impairment (AAMI; n = 21), other premorbid estimates, a one-way, repeated measures mild cognitive impairment (MCI; n = 59), or dementia (n = ANOVA was conducted, with the premorbid estimates 15). AAMI was diagnosed according to Crook and colleagues’ entered as different levels of the within-subject variable. criteria [52], MCI was classified according to Petersen and To specifically compare premorbid estimates between colleagues’ criteria [53], and dementia was assessed using the those with different levels of education, a one-way MANOVA Diagnostic and Statistical Manual of Mental Disorders (4th ed. was conducted, which examined performance on tests of text revision) [54]. Mean scores on the Mini-Mental Status premorbid intelligence among different educational groups Examination (MMSE) [55] were 29.23 (SD = 0.81) for the (i.e., 0–12, 13–16, and 17 or more years of education). To normal aging group, 28.81 (SD = 1.44) for the AAMI group, account for an interaction between the variables, a mixed- and 27.98 (SD = 1.85) for the MCI group. The dementia model ANOVA was run with educational group entered group had a mean MMSE score of 22.93 (SD = 3.83). as the between-group independent variable and premorbid estimate entered as the within-subject dependent variable. Similarly, to assess differences among those with varying 2.2. Materials. The 45-item AMNART [31] was adminis- degrees of cognitive impairment, a one-way MANOVA tered as the primary estimate of premorbid ability as part was conducted that examined premorbid estimates between of a larger neuropsychological battery that included the diagnostic groups. To consider an interaction, a mixed- MMSE [55] and eight subtests of the WAIS-III [34]. On model ANOVA was run with diagnostic group entered as the AMNART, errors in pronunciation were tallied and the between-groups independent variable and premorbid served as the raw score. AMNART-estimated IQ score was estimate entered as the within-subjects dependent variable. calculated using Grober and Sliwinski’s formula [31], which also accounts for years of education. Other premorbid estimates included WAIS-III Verbal IQ (VIQ) and WAIS-III 3. Results Information subtest (Information) scores [34, 56]. All scores were then converted to z-scores for standardization and ease AMNART-estimated IQ was significantly correlated with in statistical analyses. Information z-scores were based on education, MMSE, VIQ, and Information (see Table 1 for 4 Journal of Aging Research Table 2: Premorbid estimate means among diagnostic and educa- descriptive and inferential statistics). AMNART performance tional groups. was not correlated with age, and a t-test did not reveal significant gender differences in amnart scores, ps = ns. AMNART Information Group VIQ z-score z-score z-score 3.1. Differences between AMNART and Other Premorbid Esti- Diagnostic Group mates. A one-way, repeated measures ANOVA revealed sig- Normal Aging 1.56 1.27 1.24 nificant differences between premorbid estimates, (3, 369) = AAMI 1.34 1.30 1.38 35.61, p< .001. A Scheffe’s post hoc test indicated that MCI 1.28 0.53 0.78 AMNART-estimated IQ was significantly higher than all Dementia 0.83 −0.31 0.13 other premorbid estimates, ps <.01. Educational group 0–12 years 0.88 0.18 0.35 3.2. Premorbid Estimates and Education. Aone-way 13–16 years 1.28 0.70 0.86 MANOVA indicated significant differences between educa- 17+ years 1.53 1.10 1.26 tional groups for AMNART-estimated IQ, F(2, 127) = 11.95; VIQ, F(2, 123) = 6.17; and Information scores, F(2, 124) = 5.69, ps <.01 (see Table 2 for means). Scheffe post hoc analyses revealed that the participants with 0–12 years of education had significantly lower scores on all premorbid measures than those with 17 or more years of education, 1.5 ps <.02. AMNART scores for those with 0–12 years of education were significantly lower than scores for those with 13–16 years of education, which in turn were significantly lower than scores for those with 17 or more years of education, ps <.03. A mixed-model ANOVA did not reveal a significant inter- 0.5 action between educational group and premorbid estimate scores, F(6, 363) = 0.60, p = ns. 3.3. Premorbid Estimates and Diagnostic Groups. Aone-way MANOVA indicated significant differences among diagnostic groups for AMNART-estimated IQ, F(3, 126) = 8.60; VIQ, −0.5 F(3, 122) = 15.85; Information scores, F(3, 123) = 6.58, Normal aging AAMI MCI Dementia ps <.001 (see Table 2 for means). Scheffe post hoc analyses revealed that AMNART-estimated IQ and VIQ scores were Diagnostic group significantly lower for those in the dementia group than for AMNART those in all other diagnostic groups, ps <.05. VIQ scores VIQ Information were significantly lower in the MCI group than in the normal aging and AAMI groups, ps <.01, and there was a trend Figure 1: Interaction between diagnostic group and premorbid toward significance for AMNART scores to be higher in the estimate. MCI group than in the normal aging group, p< .06. In addition, Information scores were significantly lower in the dementia group than in the normal aging and AAMI groups, overinflate premorbid estimates among those with greater ps <.01. cognitive impairment and lower levels of education. A mixed-model ANOVA revealed a significant inter- Overall, AMNART-estimated IQ was found to be sig- action between diagnostic group and premorbid estimate, nificantly higher than scores on other indices of premorbid F(9, 360) = 8.39, p< .001, such that the discrepancy ability, namely, WAIS-III VIQ and Information. In fact, between AMNART scores and other premorbid estimates the mean AMNART score was an average of one-half increased with greater cognitive impairment (see Figure 1). standard deviation above the other premorbid estimates. This suggests that the AMNART may be an overestimation of premorbid ability in comparison with other established 4. Discussion premorbid measures. While it is important not to under- This study was designed to investigate the AMNART’s utility estimate premorbid IQ, it is also equally crucial to avoid as an estimate of premorbid functioning for older adults. overestimation of premorbid ability. For instance, if an older Consistent with the original hypotheses and the intimations adult was premorbidly performing in the average range but is of other research [44–46], the results suggest that the estimated to have high average premorbid intelligence on the AMNART may overestimate premorbid ability relative to AMNART, this would alter the threshold for determining the other tests of premorbid intelligence. In particular, it may level or extent of cognitive impairment. For this individual, a z-score Journal of Aging Research 5 clinician using the AMNART might classify cognitive decline across diagnostic groups, particularly among those with as any score in the lower end of the average range, when in the greatest cognitive impairment. This overestimation of fact these scores may be within normal limits and consistent premorbid IQ among those with greater cognitive impair- with that older adult’s premorbid functioning. Thus, an ment is particularly troubling, since premorbid measures are overestimation of premorbid intelligence is linked to an often of greater importance when working with individuals increased false positive rate for diagnosing the presence and whose current level of cognitive functioning no longer severity of cognitive impairment. Patients may be diagnosed matches their premorbid abilities, such as older adults with with a more severe form of cognitive impairment than is dementia. objectively present. In addition, clinicians will have difficulty When interpreting and generalizing these results, one providing the best treatment to a patient without a clear should keep in mind particular limitations. AMNART- and accurate assessment of his or her premorbid func- estimated IQ was calculated using a regression equation tioning. These are potentially detrimental and misleading that was developed in conjunction with the WAIS-R [31]. errors. Therefore, any comparison between AMNART-estimated When educational groupings were examined, there were IQ and WAIS-III scores should be held with a degree of significant differences among all groups for all premorbid tentativeness. Considering the present study’s participants, estimates. It would be expected that those who have com- a convenience sample was used; therefore, those who par- pleted more years of education would have a higher level ticipated may be more concerned about their memory or of premorbid functioning, which is consistent with our interested in scientific research than those who chose not findings. However, a qualitative analysis of the premorbid to participate. In addition, the sample was highly educated, estimate means for those with 0–12 years of education yields with the average level of education just under 16 years (i.e., interesting results. WAIS-III VIQ Information scores for a bachelor’s degree). There were a limited number of partici- those with 0–12 years of education were in the average range pants with a high school education, so the present findings (57th and 64th percentiles, resp.), whereas mean AMNART- regarding educational groups should be interpreted with estimated IQ was in the high average range (81st percentile). some degree of caution. Similarly, the diagnostic group sizes This raises an important question of whether the premorbid were not equivalent. Finally, the sample was predominantly ability of those with 0–12 years of education, whose highest Caucasian. Future research should continue to explore these educational attainment would be a high school diploma, issues with a sample that is more evenly distributed and should be estimated in the high average range based on the representative of the population. The implementation of a AMNART. Rather, those who have a high school education longitudinal design may contribute important information should generally cluster around average premorbid skills [9]. as to how premorbid estimates change with time and This again suggests that the AMNART may overestimate the development of cognitive decline. Finally, this study premorbid ability among older adults. It was also discovered that there was a significant decline should be replicated to compare AMNART-estimated IQ in AMNART-estimated IQ scores among those with demen- with WAIS-IV premorbid estimates. tia, implying that the AMNART does not remain unaffected by increased cognitive impairment. This is consistent with previous research [44–47] and is expected considering that 5. Conclusions as a performance-based cognitive measure, the AMNART should be somewhat affected by progressive dementia. This Overall, the AMNART appears to be an overestimation of finding could also suggest that the AMNART is increasingly premorbid ability in older adults. Comparison with other less valid as individuals develop a greater degree of cognitive premorbid measures indicates that the AMNART seems decline. This is supported by the finding that the discrepancy to be most appropriate for use with those with higher between AMNART-estimated IQ and all other premor- levels of education, as well as with those experiencing bid estimates increased with greater cognitive impairment. normal aging. However, for all groups, the AMNART appears AMNART-estimated IQ was particularly inflated relative to to yield an inflated estimate of premorbid ability. These other premorbid estimates among older adults with MCI and overestimates are clinically relevant, since such discrepancies dementia. It may be that the AMNART is most accurate as between actual premorbid ability and AMNART-estimated a premorbid estimate among those with normal aging, but IQ may lead to misdiagnosis of cognitive impairment or the evidence from this study suggests that it even overinflates to the overestimation of the severity of cognitive decline. premorbid functioning in the normal aging group, as well as Collectively, these results suggest that the AMNART should other aging-related diagnostic groups. Another possibility is be used cautiously with older adults, especially those with that AMNART-estimated IQ may be less affected by cognitive cognitive impairment or lower levels of education. 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Estimating Premorbid Intelligence among Older Adults: The Utility of the AMNART

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Copyright © 2011 Deborah A. Lowe and Steven A. Rogers. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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SAGE-Hindawi Access to Research Journal of Aging Research Volume 2011, Article ID 428132, 7 pages doi:10.4061/2011/428132 Research Article Estimating Premorbid Intelligence among Older Adults: The Utility of the AMNART Deborah A. Lowe and Steven A. Rogers Department of Psychology, Westmont College, 955 La Paz Road, Santa Barbara, CA 93108, USA Correspondence should be addressed to Deborah A. Lowe, delowe@westmont.edu Received 7 July 2010; Revised 7 January 2011; Accepted 24 February 2011 Academic Editor: Astrid E. Fletcher Copyright © 2011 D. A. Lowe and S. A. Rogers. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This study examines the utility of the American version of the National Adult Reading Test (AMNART) as a measure of premorbid intelligence for older adults. In a sample of 130 older adults, aged 56 to 104, the AMNART was compared to other tests of premorbid intelligence. The results revealed that AMNART-estimated IQ was significantly higher than other premorbid estimates. Across specific educational groups (i.e., 0–12, 13–16, and 17 or more years of education), AMNART-estimated IQ was inflated relative to all other premorbid estimates. The AMNART also declined as cognitive impairment increased, and there was a significant interaction between aging-related diagnostic group and premorbid estimate. The AMNART may therefore overestimate premorbid ability relative to other premorbid measures, particularly among those with greater cognitive impairment and lower levels of education. These results suggest that the AMNART should be used cautiously among older adults and in conjunction with other estimates of premorbid ability. 1. Estimating Premorbid Intelligence among One approach to assessing premorbid functioning among older adults involves the use of demographic vari- Older Adults: The Utility of the AMNART ables, such as education, sex, handedness, and occupation Considering the rapidly burgeoning older population, in- [1]. This approach can be useful because the data are gained creased attention is being given to an accurate assessment of without lengthy or invasive testing and independent of the older adults’ cognitive and neuropsychological functioning. patient’s current cognitive functioning and therefore remain Part of this process involves obtaining a viable estimate of constant throughout the patient’s adult life without being their premorbid cognitive ability or their expected perfor- affected by any cognitive decline that may occur [2]. The use mance prior to any injury or relative decline in cognitive of demographic variables has been shown in some studies functioning. These premorbid estimates are critical toward to be a good estimate of premorbid intelligence among determining the nature, type, and severity of cognitive healthy controls [3] and has been recommended over other impairment. It is vital when estimating the level of cognitive premorbid estimates for those with Alzheimer’s disease [4]. decline to account for variations in premorbid ability. For Demographic variables have been found in some cases to example, an older adult might be performing in the average improve the accuracy of alternative approaches [5]. However, range relative to his or her peers, but this could be a potential other studies have found that demographic indices involving decline if his or her previous premorbid abilities were in education in particular are not always the most accurate the high average or superior range. It is also important to estimates of premorbid intelligence in normal aging and obtain a premorbid indicator in addition to age-based norms Alzheimer’s disease [6–8], perhaps reflecting the intellectual to account for other factors, such as formal education and development that may occur beyond formal education and occupation, that can contribute to one’s intellectual abilities. continue throughout one’s life. To this end, various approaches have been developed to To address some of the inadequacies in relying solely estimate premorbid intelligence. upon demographic variables, other methods of estimating 2 Journal of Aging Research premorbid intelligence have been suggested, such as the have suggested that the AMNART is a good estimate of Wechsler Adult Intelligence Scale (WAIS) Verbal IQ, Infor- premorbid ability for older adults [31–33]. Pavlik et al. [34] mation, and Vocabulary subtest scores [2, 9]. The most discovered that it was a better premorbid estimate than common approach is the use of word reading tests, which demographic variables, which do not account for intellectual require the participant to verbally pronounce orthograph- development occurring after the completion of one’s formal ically irregular words (e.g., “ache” or “hyperbole”). It is education. However, Gladsjo and colleagues [32]found that assumed that correct pronunciation of these words, which the AMNART’s predictive strength was improved when it was do not follow common English grammatical rules, implies used in conjunction with demographic estimates. prior knowledge of them and therefore a higher premorbid One limitation of the AMNART and similar word reading intelligence [2]. A variety of different word reading tests tests (e.g., NART, NAART) is that they were developed as pre- have been developed, all of which have their own particular morbid estimates in comparison with the WAIS-Revised strengths and weaknesses. (WAIS-R) [35]. AMNART-estimated IQ, as calculated by One of the most common word reading tests is the using Grober and Sliwinski’s regression equation [31], there- National Adult Reading Test (NART) [10, 11], which requires fore predicts premorbid intelligence in comparison with participants to read aloud a list of 50 irregular words. The WAIS-R normative values. Updated regression equations NART appears to be a good estimate for healthy older have not been published to convert AMNART-estimated adults [12] and has been shown to be more resistant to IQ to the newer normative samples of the WAIS-Third the effects of age than the WAIS Vocabulary subtest [13– Edition (WAIS-III) [36] or WAIS-Fourth Edition (WAIS-IV) 15]. Although some researchers have found the NART to [37]. Despite the slightly outdated regression equation, the be a good premorbid estimate among those with dementia AMNART remains a commonly used premorbid estimate, [12, 15–17], others have found that it actually declines in even in conjunction with the WAIS-III [38–42]. In fact, dementia, therefore implying that it is not impervious to even after the publication of the WAIS-III, Schinka and the effects of cognitive impairment [4, 18–20]. Similarly, Vanderploeg [43] still recommend using the AMNART or whilesomeresearchers recommend that the NART should a similar reading test along with demographic information not be used among all adult populations, particularly those (e.g., education level) and select WAIS-III subtests (e.g., In- with organic conditions such as schizophrenia, Korsakoff formation, Vocabulary) when attempting to predict premor- psychosis, or Huntington’s disease [13, 21], others have not bid performance. In the absence of regression equations that found any declines related to these conditions [16]. are updated for WAIS-III or WAIS-IV normative values, the There has also been mixed evidence regarding the utility AMNART is still commonly used as a premorbid estimate. of other word reading tests. Alexander and colleagues [6] In addition, there is insufficient amount of data regarding found that the reading subtest of the Wide Range Achieve- the utility of the AMNART as a premorbid estimate for older ment Test (WRAT) [22] correlated better than demographic adults. Some researchers have argued that the AMNART estimates as a cerebral metabolic measure of premorbid is not an equally valid measure for all populations and cognitive functioning. The North American Adult Reading that it should be used with caution. Boekamp et al. [44] Test (NAART) [23] was also found to be better than found that the AMNART is an overestimate of premorbid education as an estimate of both premorbid intelligence and functioning for those with lower intelligence, which may overall cognitive functioning [7, 9]. Johnstone et al. [24] reflect a floor effect in the regression equation or a third, found that both the WRAT and the NAART were equally mediating variable. In addition, researchers have indicated accurate premorbid estimates for those in the average range that the AMNART significantly declines in dementia and of intelligence, but they were significant overestimates for have recommended against its use among those with those with lower intelligence and underestimates for those cognitive impairment [44–46]. AMNART scores have even with higher intelligence. The Spot-the-Word Test [25], which been found to decline before the diagnosis of dementia is allows participants to choose the correct low-frequency ever made, perhaps suggesting a link to the depletion of English word from a pair of words that includes a nonword, one’s cognitive reserve [47], which is the ability to employ has been found to be a good estimate for older adults with compensatory cognitive strategies and utilize a variety of normal aging and even mild forms of dementia [3], but it neural networks for problem solving. Cognitive reserve is appears to significantly decline in moderate-to-severe forms developed by factors such as education, occupation, and of dementia [26, 27]. The Cambridge Contextual Reading leisure activities and has been shown to act as a buffer Test [28], which places NART words within a semantic against cognitive decline [48–51]. The larger one’s cognitive context, seems to be a better estimate than the NART for reserve, the greater the degree of cognitive deterioration that those who have dementia or lower reading ability [26–30]. must occur before symptoms of dementia or other forms of Another commonly used word reading test, the American cognitive impairment can be detected. Therefore, a decline in version of the NART (AMNART) [31], was developed for AMNART-estimated IQ, even before any formal diagnosis of American English speakers in the USA. Depending on the cognitive impairment, may indicate an insidious depletion of version, this test consists of either 45 or 50 orthographically one’s cognitive reserve. irregular English words, with about half identical to NART In light of the inconclusive data regarding the AMNART, items [2]. During administration, participants are instructed this study examined the utility of AMNART-estimated intel- to pronounce each word out loud, beginning at the top of ligence scores as a measure of premorbid cognitive ability in the list and continuing through the end. Some researchers older adults. This included examining how it compared to Journal of Aging Research 3 Table 1: Correlations between AMNART and variables of interest. other commonly used measures of premorbid intelligence, namely, education, WAIS-III Verbal IQ, and the WAIS- Variable rM SD III Information subtest [2]. To specifically examine the Age −0.01 78.70 10.34 AMNART’s utility among adults with varying levels of Education 0.42 15.62 2.61 education, premorbid measures were examined between MMSE 0.41 27.87 2.67 different educational groupings. Similarly, the AMNART was Premorbid estimate compared to other premorbid estimates among different AMNART z-score — 1.31 0.51 aging-related diagnostic groups to consider its utility as cognitive functioning declines. In light of the limitations VIQ z-score 0.70 0.78 0.97 highlighted by other researchers, it was hypothesized that Information z-score 0.68 0.94 0.99 AMNART-estimated premorbid ability would be signifi- Note. Due to occasional missing data, the smallest sample size was 124. cantly higher than all other premorbid measures and that it p< .001. would be an overestimate of premorbid functioning for those with dementia and lower levels of education. The final results can help clarify and illuminate the most accurate assessment the normative data provided in the administration manual of older adults’ premorbid cognitive and intellectual abilities. [34]. VIQ and AMNART-estimated IQ scores were converted to z-scores based on a mean IQ score of 100 and standard deviation of 15. 2. Method 2.3. Procedure. All participants were given information 2.1. Participants. One hundred and thirty community- about the study, and they provided informed consent. They dwelling older adults (69% female, 95% Caucasian) between were notified that they would have the option for free the ages of 56 and 104 voluntarily completed a comprehen- feedback at a later time. A brief interview was conducted to sive neuropsychological battery (see Table 1 for demographic information). All data were gathered in compliance with gather demographic information, as well as to ascertain the presence of subjective memory complaints and difficulties the Institutional Review Board affiliated with the authors’ with activities of daily living. Participants were then adminis- institution. For purposes of examining measures of premorbid tered a comprehensive neuropsychological battery that took approximately three hours to be completed. ability among older adults at various levels of educational attainment, the sample was divided into three educational groups: those with 0–12 years of education (i.e., high school 2.4. Statistical Analyses. Correlations were conducted or lower; n = 17), those with 13–16 years of education between the AMNART and demographic variables, as well as (i.e., college; n = 68), and those with 17 or more years of between the AMNART and all other estimates of premorbid education (i.e., graduate school; n = 45). functioning (i.e., WAIS-III VIQ and Information). To Participants were classified as having normal aging (n = explore differences in means between the AMNART and 35), age-associated memory impairment (AAMI; n = 21), other premorbid estimates, a one-way, repeated measures mild cognitive impairment (MCI; n = 59), or dementia (n = ANOVA was conducted, with the premorbid estimates 15). AAMI was diagnosed according to Crook and colleagues’ entered as different levels of the within-subject variable. criteria [52], MCI was classified according to Petersen and To specifically compare premorbid estimates between colleagues’ criteria [53], and dementia was assessed using the those with different levels of education, a one-way MANOVA Diagnostic and Statistical Manual of Mental Disorders (4th ed. was conducted, which examined performance on tests of text revision) [54]. Mean scores on the Mini-Mental Status premorbid intelligence among different educational groups Examination (MMSE) [55] were 29.23 (SD = 0.81) for the (i.e., 0–12, 13–16, and 17 or more years of education). To normal aging group, 28.81 (SD = 1.44) for the AAMI group, account for an interaction between the variables, a mixed- and 27.98 (SD = 1.85) for the MCI group. The dementia model ANOVA was run with educational group entered group had a mean MMSE score of 22.93 (SD = 3.83). as the between-group independent variable and premorbid estimate entered as the within-subject dependent variable. Similarly, to assess differences among those with varying 2.2. Materials. The 45-item AMNART [31] was adminis- degrees of cognitive impairment, a one-way MANOVA tered as the primary estimate of premorbid ability as part was conducted that examined premorbid estimates between of a larger neuropsychological battery that included the diagnostic groups. To consider an interaction, a mixed- MMSE [55] and eight subtests of the WAIS-III [34]. On model ANOVA was run with diagnostic group entered as the AMNART, errors in pronunciation were tallied and the between-groups independent variable and premorbid served as the raw score. AMNART-estimated IQ score was estimate entered as the within-subjects dependent variable. calculated using Grober and Sliwinski’s formula [31], which also accounts for years of education. Other premorbid estimates included WAIS-III Verbal IQ (VIQ) and WAIS-III 3. Results Information subtest (Information) scores [34, 56]. All scores were then converted to z-scores for standardization and ease AMNART-estimated IQ was significantly correlated with in statistical analyses. Information z-scores were based on education, MMSE, VIQ, and Information (see Table 1 for 4 Journal of Aging Research Table 2: Premorbid estimate means among diagnostic and educa- descriptive and inferential statistics). AMNART performance tional groups. was not correlated with age, and a t-test did not reveal significant gender differences in amnart scores, ps = ns. AMNART Information Group VIQ z-score z-score z-score 3.1. Differences between AMNART and Other Premorbid Esti- Diagnostic Group mates. A one-way, repeated measures ANOVA revealed sig- Normal Aging 1.56 1.27 1.24 nificant differences between premorbid estimates, (3, 369) = AAMI 1.34 1.30 1.38 35.61, p< .001. A Scheffe’s post hoc test indicated that MCI 1.28 0.53 0.78 AMNART-estimated IQ was significantly higher than all Dementia 0.83 −0.31 0.13 other premorbid estimates, ps <.01. Educational group 0–12 years 0.88 0.18 0.35 3.2. Premorbid Estimates and Education. Aone-way 13–16 years 1.28 0.70 0.86 MANOVA indicated significant differences between educa- 17+ years 1.53 1.10 1.26 tional groups for AMNART-estimated IQ, F(2, 127) = 11.95; VIQ, F(2, 123) = 6.17; and Information scores, F(2, 124) = 5.69, ps <.01 (see Table 2 for means). Scheffe post hoc analyses revealed that the participants with 0–12 years of education had significantly lower scores on all premorbid measures than those with 17 or more years of education, 1.5 ps <.02. AMNART scores for those with 0–12 years of education were significantly lower than scores for those with 13–16 years of education, which in turn were significantly lower than scores for those with 17 or more years of education, ps <.03. A mixed-model ANOVA did not reveal a significant inter- 0.5 action between educational group and premorbid estimate scores, F(6, 363) = 0.60, p = ns. 3.3. Premorbid Estimates and Diagnostic Groups. Aone-way MANOVA indicated significant differences among diagnostic groups for AMNART-estimated IQ, F(3, 126) = 8.60; VIQ, −0.5 F(3, 122) = 15.85; Information scores, F(3, 123) = 6.58, Normal aging AAMI MCI Dementia ps <.001 (see Table 2 for means). Scheffe post hoc analyses revealed that AMNART-estimated IQ and VIQ scores were Diagnostic group significantly lower for those in the dementia group than for AMNART those in all other diagnostic groups, ps <.05. VIQ scores VIQ Information were significantly lower in the MCI group than in the normal aging and AAMI groups, ps <.01, and there was a trend Figure 1: Interaction between diagnostic group and premorbid toward significance for AMNART scores to be higher in the estimate. MCI group than in the normal aging group, p< .06. In addition, Information scores were significantly lower in the dementia group than in the normal aging and AAMI groups, overinflate premorbid estimates among those with greater ps <.01. cognitive impairment and lower levels of education. A mixed-model ANOVA revealed a significant inter- Overall, AMNART-estimated IQ was found to be sig- action between diagnostic group and premorbid estimate, nificantly higher than scores on other indices of premorbid F(9, 360) = 8.39, p< .001, such that the discrepancy ability, namely, WAIS-III VIQ and Information. In fact, between AMNART scores and other premorbid estimates the mean AMNART score was an average of one-half increased with greater cognitive impairment (see Figure 1). standard deviation above the other premorbid estimates. This suggests that the AMNART may be an overestimation of premorbid ability in comparison with other established 4. Discussion premorbid measures. While it is important not to under- This study was designed to investigate the AMNART’s utility estimate premorbid IQ, it is also equally crucial to avoid as an estimate of premorbid functioning for older adults. overestimation of premorbid ability. For instance, if an older Consistent with the original hypotheses and the intimations adult was premorbidly performing in the average range but is of other research [44–46], the results suggest that the estimated to have high average premorbid intelligence on the AMNART may overestimate premorbid ability relative to AMNART, this would alter the threshold for determining the other tests of premorbid intelligence. In particular, it may level or extent of cognitive impairment. For this individual, a z-score Journal of Aging Research 5 clinician using the AMNART might classify cognitive decline across diagnostic groups, particularly among those with as any score in the lower end of the average range, when in the greatest cognitive impairment. This overestimation of fact these scores may be within normal limits and consistent premorbid IQ among those with greater cognitive impair- with that older adult’s premorbid functioning. Thus, an ment is particularly troubling, since premorbid measures are overestimation of premorbid intelligence is linked to an often of greater importance when working with individuals increased false positive rate for diagnosing the presence and whose current level of cognitive functioning no longer severity of cognitive impairment. Patients may be diagnosed matches their premorbid abilities, such as older adults with with a more severe form of cognitive impairment than is dementia. objectively present. In addition, clinicians will have difficulty When interpreting and generalizing these results, one providing the best treatment to a patient without a clear should keep in mind particular limitations. AMNART- and accurate assessment of his or her premorbid func- estimated IQ was calculated using a regression equation tioning. These are potentially detrimental and misleading that was developed in conjunction with the WAIS-R [31]. errors. Therefore, any comparison between AMNART-estimated When educational groupings were examined, there were IQ and WAIS-III scores should be held with a degree of significant differences among all groups for all premorbid tentativeness. Considering the present study’s participants, estimates. It would be expected that those who have com- a convenience sample was used; therefore, those who par- pleted more years of education would have a higher level ticipated may be more concerned about their memory or of premorbid functioning, which is consistent with our interested in scientific research than those who chose not findings. However, a qualitative analysis of the premorbid to participate. In addition, the sample was highly educated, estimate means for those with 0–12 years of education yields with the average level of education just under 16 years (i.e., interesting results. WAIS-III VIQ Information scores for a bachelor’s degree). There were a limited number of partici- those with 0–12 years of education were in the average range pants with a high school education, so the present findings (57th and 64th percentiles, resp.), whereas mean AMNART- regarding educational groups should be interpreted with estimated IQ was in the high average range (81st percentile). some degree of caution. Similarly, the diagnostic group sizes This raises an important question of whether the premorbid were not equivalent. Finally, the sample was predominantly ability of those with 0–12 years of education, whose highest Caucasian. Future research should continue to explore these educational attainment would be a high school diploma, issues with a sample that is more evenly distributed and should be estimated in the high average range based on the representative of the population. The implementation of a AMNART. Rather, those who have a high school education longitudinal design may contribute important information should generally cluster around average premorbid skills [9]. as to how premorbid estimates change with time and This again suggests that the AMNART may overestimate the development of cognitive decline. Finally, this study premorbid ability among older adults. It was also discovered that there was a significant decline should be replicated to compare AMNART-estimated IQ in AMNART-estimated IQ scores among those with demen- with WAIS-IV premorbid estimates. tia, implying that the AMNART does not remain unaffected by increased cognitive impairment. This is consistent with previous research [44–47] and is expected considering that 5. Conclusions as a performance-based cognitive measure, the AMNART should be somewhat affected by progressive dementia. This Overall, the AMNART appears to be an overestimation of finding could also suggest that the AMNART is increasingly premorbid ability in older adults. Comparison with other less valid as individuals develop a greater degree of cognitive premorbid measures indicates that the AMNART seems decline. This is supported by the finding that the discrepancy to be most appropriate for use with those with higher between AMNART-estimated IQ and all other premor- levels of education, as well as with those experiencing bid estimates increased with greater cognitive impairment. normal aging. However, for all groups, the AMNART appears AMNART-estimated IQ was particularly inflated relative to to yield an inflated estimate of premorbid ability. These other premorbid estimates among older adults with MCI and overestimates are clinically relevant, since such discrepancies dementia. It may be that the AMNART is most accurate as between actual premorbid ability and AMNART-estimated a premorbid estimate among those with normal aging, but IQ may lead to misdiagnosis of cognitive impairment or the evidence from this study suggests that it even overinflates to the overestimation of the severity of cognitive decline. premorbid functioning in the normal aging group, as well as Collectively, these results suggest that the AMNART should other aging-related diagnostic groups. Another possibility is be used cautiously with older adults, especially those with that AMNART-estimated IQ may be less affected by cognitive cognitive impairment or lower levels of education. 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