Subtle Deficits in Instrumental Activities of Daily Living in Subtypes of Mild Cognitive Impairment

doi:10.1159/000313540

Dement Geriatr Cogn Disord. 2010 November; 30(3): 189–197.

Published online 2010 August 26. doi: 10.1159/000313540

PMCID: PMC2948658

Subtle Deficits in Instrumental Activities of Daily Living in Subtypes of Mild Cognitive Impairment

Edmond Teng,^a^b^c^* Brian W. Becker,^b Ellen Woo,^c Jeffrey L. Cummings,^c^d and Po H. Lu^c

^aNeurobehavior Unit, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, Calif., USA

^bGeriatric Research Education and Clinical Center, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, Calif., USA

^cDepartment of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, Calif., USA

^dDepartment of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, Calif., USA

*Edmond Teng, MD, PhD, Neurobehavior Unit (116AF), West Los Angeles VA Healthcare Center, Building 500, 11301 Wilshire Boulevard, Los Angeles, CA 90073 (USA), Tel. +1 310 478 3711, ext. 49633, Fax +1 310 268 4181, E-Mail eteng/at/ucla.edu

Accepted April 7, 2010.

This is an open access article distributed under the terms of Karger's Author's Choice™ licensing agreement, adapted from the Creative Commons Attribution Non-Commercial 2.5 license. This license allows authors to re-use their articles for educational and research purposes as long as the author and the journal are fully acknowledged.

This article has been cited by other articles in PMC.

Abstract

Background/Aims

Greater cognitive and functional deficits in mild cognitive impairment (MCI) are associated with higher rates of dementia. We explored the relationship between these factors by comparing instrumental activities of daily living (IADLs) among cognitive subtypes of MCI and examining associations between IADL and neuropsychological indices.

Methods

We analyzed data from 1,108 MCI and 3,036 normal control subjects included in the National Alzheimer's Coordinating Center Uniform Data Set who were assessed with the Functional Activities Questionnaire (FAQ).

Results

IADL deficits were greater in amnestic than nonamnestic MCI, but within these subgroups, did not differ between those with single or multiple domains of cognitive impairment. FAQ indices correlated significantly with memory and processing speed/executive function.

Conclusions

IADL deficits are present in both amnestic MCI and nonamnestic MCI but are not related to the number of impaired cognitive domains. These cross-sectional findings support previous longitudinal reports suggesting that cognitive and functional impairments in MCI may be independently associated with dementia risk.

Key Words: Mild cognitive impairment, Functional impairment, Activities of daily living, Memory performance, Executive function

Introduction

Mild cognitive impairment (MCI) has been conceptualized as an intermediate stage between normal aging and dementia. General guidelines for the diagnosis of MCI include the presence of objective cognitive impairment and essentially intact activities of daily living (ADLs) [1]. These criteria are designed to distinguish MCI from both normal aging and mild dementia [although the presence of functional impairment is only a supportive feature in the NINCDS-ADRDA criteria for Alzheimer's disease (AD) [2]] and identify a population of subjects with an elevated risk of progression to dementia [3]. In an effort to improve diagnostic specificity, MCI has been further subdivided into subtypes based on the presence or absence of memory deficits and whether single or multiple cognitive domains are impaired [1]. Several studies indicate that subjects meeting criteria for multiple-domain amnestic (mdAMN) MCI are most likely to subsequently progress to clinical AD [4,5,6,7].

Although current criteria for MCI specify ‘essentially intact’ ADLs, numerous reports suggest that subjects with MCI exhibit subtle but significant deficits in instrumental ADLs (IADLs) relative to normal controls (NC) [8,9,10,11,12,13,14,15,16]. Even mild IADL impairment has consistently been associated with increased rates of progression from MCI to dementia [10, 17,18,19,20]. Previous work in elderly populations has emphasized the importance of executive and/or memory function [21,22,23,24,25,26,27] in the performance of IADLs. However, some investigators have found that the increased risk of dementia associated with impaired IADLs appears to be independent of the degree of cognitive impairment [10, 19] and others have argued that deficits in IADLs may merely reflect duration of cognitive impairment [28].

One approach to examining the relative roles of functional and cognitive impairment for dementia risk in MCI is to explore differences in IADLs between cognitive subtypes of MCI. Conceptually, subjects with mdAMN MCI, who are at the highest risk of subsequent dementia, might also be expected to have the greatest deficits on standardized IADL assessments. However, the relatively few studies that have investigated IADLs in MCI subtypes have yielded inconsistent results. Many [16, 29,30,31], but not all [14] investigators have reported greater IADL deficits in multiple-domain MCI than in single-domain MCI. Similarly, IADL deficits may [14] or may not [30]be greater in amnestic MCI than in nonamnestic MCI. Studies that incorporate multiple IADL assessments report differences between MCI subgroups on some scales but not others [30, 31], suggesting that specific features of each measure (which IADLs included, self vs. informant report, questionnaire vs. performance-based) may significantly impact results. This literature is further complicated by inherent differences in sample sizes, diagnostic criteria for MCI, and population demographics across studies.

We addressed this issue by exploring the relationship between cognitive and functional impairment in MCI within the large multicenter cohort of subjects included in the standardized Uniform Data Set (UDS) compiled by the National Alzheimer's Coordinating Center (NACC) [32]. The primary goal of the present study was to compare IADLs measured with the Functional Activities Questionnaire (FAQ) [33] between subjects diagnosed with different cognitive subtypes of MCI. A secondary aim was to clarify the association between cognitive ability (determined by subjects’ neuropsychological testing performance) and functional ability (determined by informant ratings of subjects’ IADL performance) in this MCI cohort.

Methods

Research Participants

The NACC UDS contains data from 31 Alzheimer's Disease Centers (ADCs) with current or prior funding from the National Institute on Aging. We identified 1,108 MCI and 3,036 NC subjects who were ≥50 years old, had Mini-Mental State Examination (MMSE) [34] scores ≥24, were assessed with the FAQ, and whose data had been entered into the UDS by May 29, 2007. MCI was a clinical diagnosis based on the Petersen criteria [1]. Subjective cognitive complaints and functional status were determined by clinician interview and judgment. Objective cognitive impairment was independently determined at each ADC through clinician judgment and/or neuropsychological testing (including additional measures beyond those incorporated in the UDS). MCI subjects were classified into single-domain amnestic (sdAMN; n = 532), mdAMN (n = 340), single-domain nonamnestic (sdNON; n = 162), and multiple-domain nonamnestic (mdNON; n = 74) groups based upon the presence or absence of memory and/or other cognitive impairment (attention, language, visuospatial, executive). To ensure a broad sampling of MCI subtypes, all subjects meeting the Petersen criteria were included, irrespective of their scores on the Hachinski Ischemic Scale [35]. Data from these subjects has previously been included in a study examining the utility of the FAQ for distinguishing MCI from very mild AD [36]. NC subjects were determined to have normal cognition by each ADC using similar methodology. Written consent, approved by the Institutional Review Board of each center, was obtained from each subject.

Functional Assessment

IADLs were quantified using the FAQ [33]. This instrument was administered to an informant, who rated each subject's performance over the preceding 4 weeks on 10 separate categories of IADLs: (1) writing checks, paying bills, keeping financial records; (2) assembling tax or business records; (3) shopping alone; (4) playing a game of skill; (5) making coffee or tea; (6) preparing a balanced meal; (7) keeping track of current events; (8) attending to and understanding a television program, book, or magazine; (9) remembering appointments, family occasions, medications; and (10) traveling out of the neighborhood. Higher scores in each category denote increasing impairment: 0 = normal; 1 = has difficulty, but does by self; 2 = requires assistance, or 3 = dependent. Activities that could not be rated, either because the subject never performed them prior to developing cognitive difficulties, or because the informant had insufficient information to provide a valid response, were not scored. Overall FAQ performance was evaluated using two separate methods: total FAQ score, which included only subjects that had valid scores on all items (82.5% of overall subject population), and average score across FAQ items with valid responses (mean FAQ item score), which included all subjects.

Neuropsychological Assessment

The UDS includes selected neuropsychological data for each subject [32,37]: MMSE [34], logical memory IA and IIA of the revised Wechsler Memory Scale (WMS-R) [38], WMS-R forward and reverse digit span [38], verbal category fluency (animals [39] and vegetables), Trail-Making Test Parts A and B [40], digit symbol of the revised Wechsler Adult Intelligence Scale (WAIS-R) [41], and the 30 odd-numbered items of the Boston Naming Test [42]. Neuropsychological testing scores from the NC group were used to generate normative data stratified by age (50–59, 60–69, 70–79, 80–89, and 90+) and years of formal education (≤12, 13–16, 17+). Performance of the MCI subjects on each test was normalized by calculating z-scores derived from this sample.

Data Analysis

Statistical analyses were performed using PASW Statistics 17.0.2 for Windows (SPSS Inc., Chicago, Ill., USA). Between-group comparisons were conducted using one-way analyses of variance for age, education, number of valid FAQ item scores, and neuropsychological performance, and Kruskal-Wallis tests for gender, race, and percentage of subjects with complete FAQ data. Global FAQ indices and individual FAQ item scores were compared between groups using analyses of covariance adjusted for demographic differences between groups in age, education, gender, race, and MMSE scores. The total number of valid FAQ item scores was used as an additional covariate for the analysis of mean FAQ item scores and the presence or absence of complete FAQ data was used as an additional fixed factor for the analysis of individual FAQ item scores. Post hoc analyses were Bonferroni corrected for multiple comparisons.

In order to examine the relationship between FAQ indices and cognitive functioning, we performed an exploratory factor analysis to identify shared underlying constructs among the measures in the UDS neuropsychological battery. Principal components analysis incorporating varimax orthogonal rotation was used because it includes the common variance across all tests as well as variance that is unique to individual measures [43]. Factor extraction was based on eigenvalues >1. Interpretation of factor components was based on highest loadings (>0.60) for each variable, and yielded a 4-factor solution (table (table1).1). Cronbach's α was calculated to measure the internal consistency of the factors. For MCI subjects with complete data on all neuropsychological assessments, domain-specific z-scores were calculated by averaging z-scores on individual tests in each cognitive domain. Linear regression analysis incorporating age, gender, race, and years of formal education was used to ascertain any associations between neuropsychological performance in individual cognitive domains and FAQ indices.

Table 1

Factor analysis of the neuropsychological assessments

Results

Demographics

Demographic data for the NC group and the MCI subgroups are shown in table table2.2. There were significant differences between groups for most variables. Bonferroni correction of post hoc comparisons resulted in critical p values of 0.005. There were fewer male participants in the sdAMN group relative to the NC (p <0.001) and mdNON (p = 0.003) groups, and in the mdAMN group relative to the NC group (p <0.001). The mdNON group consisted of a lower proportion of non-Hispanic Whites than any of the other groups (p < 0.001), and the mdAMN and sdNON groups had a lower proportion of non-Hispanic Whites than the NC and sdAMN groups (p < 0.001). The sdAMN group was older than the NC, sdNON, and mdNON groups (p < 0.001), and marginally older than the mdAMN group (p = 0.008). The NC and sdAMN groups were better educated than the mdAMN and mdNON groups (p < 0.001). MMSE scores were higher in the NC group than in each of the MCI subgroups (p < 0.001), higher in the sdNON group than in the sdAMN and mdAMN groups (p < 0.001), and higher in the sdAMN group than in the mdAMN group (p <0.001).

Table 2

Demographic information

FAQ Indices

Participants in the NC group were more likely to have complete FAQ data than their counterparts in the MCI subgroups (p < 0.001). Likewise, the average number of valid FAQ responses for the NC group was significantly greater than for the sdAMN, mdAMN, and mdNON groups (p < 0.001), and marginally greater than for the sdNON group (p = 0.006). Both the sdAMN (p = 0.005) and sdNON (p = 0.001) groups averaged a greater number of valid FAQ responses than the mdAMN group.

Total FAQ scores are shown in figure figure1a,1a, and mean FAQ item scores are shown in figure figure1b.1b. Analyses of both global FAQ indices yielded similar results. There were significant group effects after adjustment for demographic factors [total FAQ scores: F(4, 3,371) = 40.09, p < 0.001; mean FAQ item scores: F(4, 4,087) = 59.63, p < 0.001]. Bonferroni-corrected post hoc analyses (critical p = 0.005) indicated that total FAQ and mean FAQ item scores were significantly lower (indicating less functional impairment) in the NC group than in the sdAMN, mdAMN, and sdNON groups (p ≤ 0.001), and significantly lower in the sdNON group than in the sdAMN and mdAMN groups (p ≤ 0.001). Mean FAQ item scores were also lower in the mdNON group than in the sdAMN and mdAMN groups (p ≤ 0.001).

Fig. 1.

Total FAQ scores (a) and mean FAQ item scores (b) in the NC group and MCI subgroups. Error bars represent standard error of the mean. ^a p ≤ 0.001 versus NC; ^b p ≤ 0.001 versus sdNON; ^c p ≤ 0.001 versus mdNON.

Similar scores on global FAQ indices were seen between the sdAMN and mdAMN subgroups (total FAQ scores: p = 0.62; mean FAQ item scores: p = 0.43) and between the sdNON and mdNON subgroups (total FAQ scores: p = 0.88; mean FAQ item scores: p = 0.56), despite inherent demographic differences. Therefore, these subgroups were combined into respective AMN and NON groups for further analyses of individual FAQ items (fig. (fig.2),2), which included all subjects with valid responses for each item.

Fig. 2.

Individual FAQ item scores for all participants. Percentages above each bar represent the proportion of subjects with valid responses for that item. Error bars represent standard error of the mean. ^a p < 0.017 versus NC; ^b p < 0.017 versus (more ...)

After adjustment for demographic factors, there was a significant group effect for each individual FAQ item (F > 15.0, p < 0.001). NC subjects had lower scores than the AMN group on all items (p < 0.001) and lower scores than the NON group on managing bills, preparing taxes, keeping up with current events, attending to media, remembering dates, and traveling outside the neighborhood (p < 0.004). The NON group had lower scores than the AMN group on managing bills, preparing taxes, shopping, playing a game of skill, cooking, keeping track of current events, and remembering dates (p < 0.002). These findings survived Bonferroni correction (critical p = 0.017).

Correlations between FAQ Indices and Neuropsychological Performance

Neuropsychological test scores for the NC group and the MCI subgroups are shown in table table3.3. The MCI subgroups performed more poorly than the NC group on each test. As expected, amnestic MCI subgroups performed more poorly than nonamnestic MCI subgroups on memory measures and multiple-domain MCI subgroups generally performed more poorly than single-domain MCI subgroups on the other assessments.

Table 3

Neuropsychological performance (raw scores)

Multiple linear regression analyses investigating the association between the two global FAQ indices and cognitive performance in the MCI group are detailed in table table4.4. Both analyses yielded similar results, indicating that only the memory and executive/processing speed z-scores were independent predictors of global FAQ indices and that memory performance was more strongly associated with functional impairment than executive/processing speed performance. However, these models produced relative modest correlations, each accounting for only about 10% of the variance in the global FAQ indices.

Table 4

Multiple linear regression of global FAQ indices versus neuropsychological performance adjusted for demographics

Multiple linear regression models incorporating individual FAQ items produced weaker correlations, with r values ranging from 0.30 (remembering dates) to 0.16 (making tea or coffee). Memory z-scores correlated most strongly with remembering dates (β = −0.25), preparing taxes (β = −0.20), and managing bills (β = −0.19). Executive/processing speed z-scores correlated most strongly with managing bills (β = −0.17), preparing taxes (β = −0.13), and traveling outside the neighborhood (β = −0.12).

Discussion

Our results, derived from a large multicenter database, indicate that mild IADL deficits are present in both amnestic and nonamnestic MCI, with more extensive deficits reported by informants for amnestic subjects. The degree of IADL impairment was similar between amnestic subjects with single or multiple domains of cognitive impairment. Across all MCI subtypes, global IADL measures were associated with neuropsychological assessments of memory and executive function/processing speed.

Previous studies of IADLs in cognitive subtypes of MCI have produced mixed results. Some investigators have found IADL deficits only in participants meeting criteria for mdAMN MCI [16, 29]. Others have also found deficits in single-domain (both amnestic and nonamnestic) MCI [14, 31] that are similar to those reported here. These disparate results may be attributable to differences in IADL demands across cultures, population demographics, or IADL and/or cognitive assessments across studies.

We additionally found more profound IADL limitations in amnestic relative to nonamnestic MCI, which has not been consistently reported in prior studies. Wadley et al. [14] reported greater deficits in their amnestic MCI subgroup, while Burton et al. [30] found similar deficits in amnestic and nonamnestic MCI, but more extensive impairment amongst subjects with deficits in multiple cognitive domains. More recent work by Aretouli and Brandt [31] included two separate IADL assessments, yielding conflicting results that concur with both earlier studies. We were somewhat surprised to find similar IADL deficits in our sdAMN and mdAMN MCI groups. Our initial prediction, given earlier studies of IADLs in MCI subtypes [16, 29,30,31], the consistent association between IADL impairment and progression to dementia [10, 17,18,19,20], and higher rates of progression to dementia in mdAMN MCI [4,5,6,7], was that scores on global FAQ indices would be higher in our mdAMN MCI group.

There are several potential explanations for these results. The presence of memory deficits may play a larger role than the presence of additional cognitive deficits in determining IADL impairment. This interpretation is supported by our regression analyses, which indicated that memory performance was an independent predictor of global FAQ indices, and by earlier work from other groups identifying the importance of memory function in the performance of IADLs [21, 24, 27]. Nevertheless, other investigators have identified executive function as the strongest neuropsychological predictor of IADL abilities [22, 23, 25], though such discrepancies may be related to differences in the specific tests that comprise cognitive domain scores across studies. Alternatively, subjects in the UDS database with deficits in memory and other cognitive domains who exhibited greater IADL impairments may have been diagnosed with dementia and therefore been excluded from this analysis. Finally, the FAQ may be more heavily weighted towards memory-dependent IADLs than other IADLs. This last possibility seems less likely given previous work showing that total FAQ scores correlate reasonably well with other IADL indices [33] and that the sdAMN and mdAMN MCI groups in the current cohort had similar scores on each FAQ item (p > 0.05).

The important contribution of memory deficits to impaired IADLs suggested by differences in global FAQ indices between clinically diagnosed amnestic and nonamnestic MCI groups is further supported by regression analyses incorporating neuropsychological performance, which identified both memory and executive/processing speed as significant predictors of functional ability. However, the correlations between cognitive and IADL indices were relatively modest. The strength of these correlations may have been limited by the inclusion of only MCI subjects in the regression analyses, thus restricting the range of both the cognitive and FAQ scores. Some of the prior studies demonstrating more robust correlations between cognitive and functional scores included a broader spectrum of subjects, often encompassing both normal and impaired cognition [22, 25, 44]. The relatively limited battery of neuropsychological tests included in the UDS may also have reduced the strength of these correlations. In particular, the memory factor includes only two measures from a single test of verbal memory (WMS-R logical memory), and the executive/processing speed factor includes only a single test (Trail-Making Test Part B) that is associated with executive functioning [45]. Finally, these relatively weak correlations may simply reflect the possibility that similar IADL deficits may be caused by different cognitive deficits in different subjects.

MCI subjects were less likely to have complete FAQ data than NC subjects. The underlying reason for this finding remains uncertain. One possibility is that informants for the MCI groups may have been less knowledgeable about their subjects than informants for the NC group. However, given that similar results were obtained with total FAQ scores (which included only subjects with complete FAQ data) and mean FAQ item scores (which included all subjects), it is unlikely that the differences between groups in the number of valid FAQ responses significantly affected our conclusions.

There are a few other considerations that impact the interpretation of our results. The study population was comprised of a convenience sample of highly educated subjects volunteering for research at major academic centers and therefore may not be representative of epidemiological samples or those with greater ethnic diversity. Nonamnestic MCI subjects were less likely to be non-Hispanic Whites, a finding that replicates other recent studies of nonamnestic MCI [46, 47] and is consistent with previous reports of poorer performance on nonmemory cognitive assessments in non-White populations [48, 49]. Our amnestic MCI subgroups were older and included higher proportions of women than the other diagnostic groups. Although similar age differences have been reported in previous studies of amnestic MCI, such gender differences have not [50]. Diagnostic classification in the UDS is derived from clinical diagnoses determined at each individual ADC based upon the current criteria for MCI [1]. However, the operationalization of these criteria has not been consistently standardized. Although the UDS includes a core neuropsychological battery [32, 37], the NACC does not specify which additional cognitive tests can be used at each ADC to supplement that battery, does not establish specific performance thresholds for impairment, and does not stipulate the precise role of test scores in the diagnostic process. Since the specific neuropsychological tests and performance thresholds used to identify MCI can significantly influence subject classification [46, 51,52,53], it remains possible that variability in the interpretation of the diagnostic criteria for MCI across participating centers may have influenced our results. Finally, the FAQ is an informant-based assessment of IADLs, and may be susceptible to bias if informants lack or distort information regarding subjects’ functional abilities. Performance-based measures of IADLs may have better ecological validity, correlate more closely with cognitive function, and allow for more subtle distinctions among diagnostic groups [54, 55].

Our cross-sectional findings, when taken together with previous longitudinal reports [10, 19], raise the possibility that cognitive and functional deficits in MCI may independently contribute to increased risk of subsequent dementia. Although mdAMN MCI subjects have been considered the most likely to progress to dementia, their IADL deficits were similar to those seen in sdAMN MCI subjects. Conversely, although memory and executive/processing speed were independently associated with IADL performance, correlations between cognitive and functional decline were relatively modest. These results provide further support for inclusion of both cognitive and functional variables when estimating dementia risk in MCI [10, 17, 19] but require further exploration with additional longitudinal analyses.

Acknowledgements

This research was supported by grants from the National Institute on Aging (U01 AG016976 to the National Alzheimer's Coordinating Center and P50 AG16570 to the Mary S. Easton Center for Alzheimer's Disease Research at UCLA), the Alzheimer's Disease Research Centers of California, and the Sidell-Kagan Foundation. We would like to thank Nathaniel Mercaldo for his assistance with data management.

References

1. Petersen RC. Mild cognitive impairment as a diagnostic entity. J Intern Med. 2004;256:183–194. [PubMed]

2. McKhann G, Drachman D, Folstein M, Katzman R, Price D, Stadlan EM. Clinical diagnosis of Alzheimer's disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer's disease. Neurology. 1984;34:939–944. [PubMed]

3. Bruscoli M, Lovestone S. Is MCI really just early dementia? A systematic review of conversion studies. Int Psychogeriatr. 2004;16:129–140. [PubMed]

4. Rasquin SM, Lodder J, Visser PJ, Lousberg R, Verhey FR. Predictive accuracy of MCI subtypes for Alzheimer's disease and vascular dementia in subjects with mild cognitive impairment: a 2-year follow-up study. Dement Geriatr Cogn Disord. 2005;19:113–119. [PubMed]

5. Alexopoulos P, Grimmer T, Perneczky R, Domes G, Kurz A. Progression to dementia in clinical subtypes of mild cognitive impairment. Dement Geriatr Cogn Disord. 2006;22:27–34. [PubMed]

6. Busse A, Hensel A, Guhne U, Angermeyer MC, Riedel-Heller SG. Mild cognitive impairment: Long-term course of four clinical subtypes. Neurology. 2006;67:2176–2185. [PubMed]

7. Manly JJ, Tang MX, Schupf N, Stern Y, Vonsattel JP, Mayeux R. Frequency and course of mild cognitive impairment in a multiethnic community. Ann Neurol. 2008;63:494–506. [PMC free article] [PubMed]

8. Albert SM, Michaels K, Padilla M, Pelton G, Bell K, Marder K, Stern Y, Devanand DP. Functional significance of mild cognitive impairment in elderly patients without a dementia diagnosis. Am J Geriatr Psychiatry. 1999;7:213–220. [PubMed]

9. Di Carlo A, Baldereschi M, Amaducci L, Maggi S, Grigoletto F, Scarlato G, Inzitari D. Cognitive impairment without dementia in older people: prevalence, vascular risk factors, impact on disability. The Italian Longitudinal Study on Aging. J Am Geriatr Soc. 2000;48:775–782. [PubMed]

10. Tabert MH, Albert SM, Borukhova-Milov L, Camacho Y, Pelton G, Liu X, Stern Y, Devanand DP. Functional deficits in patients with mild cognitive impairment: prediction of AD. Neurology. 2002;58:758–764. [PubMed]

11. Farias ST, Mungas D, Reed BR, Harvey D, Cahn-Weiner D, Decarli C. MCI is associated with deficits in everyday functioning. Alzheimer Dis Assoc Disord. 2006;20:217–223. [PMC free article] [PubMed]

12. Perneczky R, Pohl C, Sorg C, Hartmann J, Tosic N, Grimmer T, Heitele S, Kurz A. Impairment of activities of daily living requiring memory or complex reasoning as part of the MCI syndrome. Int J Geriatr Psychiatry. 2006;21:158–162. [PubMed]

13. Cahn-Weiner DA, Farias ST, Julian L, Harvey DJ, Kramer JH, Reed BR, Mungas D, Wetzel M, Chui H. Cognitive and neuroimaging predictors of instrumental activities of daily living. J Int Neuropsychol Soc. 2007;13:747–757. [PMC free article] [PubMed]

14. Wadley VG, Crowe M, Marsiske M, Cook SE, Unverzagt FW, Rosenberg AL, Rexroth D. Changes in everyday function in individuals with psychometrically defined mild cognitive impairment in the Advanced Cognitive Training for Independent and Vital Elderly Study. J Am Geriatr Soc. 2007;55:1192–1198. [PMC free article] [PubMed]

15. Jefferson AL, Byerly LK, Vanderhill S, Lambe S, Wong S, Ozonoff A, Karlawish JH. Characterization of activities of daily living in individuals with mild cognitive impairment. Am J Geriatr Psychiatry. 2008;16:375–383. [PMC free article] [PubMed]

16. Kim KR, Lee KS, Cheong HK, Eom JS, Oh BH, Hong CH. Characteristic profiles of instrumental activities of daily living in different subtypes of mild cognitive impairment. Dement Geriatr Cogn Disord. 2009;27:278–285. [PubMed]

17. Peres K, Chrysostome V, Fabrigoule C, Orgogozo JM, Dartigues JF, Barberger-Gateau P. Restriction in complex activities of daily living in MCI: impact on outcome. Neurology. 2006;67:461–466. [PubMed]

18. Di Carlo A, Lamassa M, Baldereschi M, Inzitari M, Scafato E, Farchi G, Inzitari D. CIND and MCI in the Italian elderly: frequency, vascular risk factors, progression to dementia. Neurology. 2007;68:1909–1916. [PubMed]

19. Rozzini L, Chilovi BV, Conti M, Bertoletti E, Delrio I, Trabucchi M, Padovani A. Conversion of amnestic mild cognitive impairment to dementia of Alzheimer type is independent to memory deterioration. Int J Geriatr Psychiatry. 2007;22:1217–1222. [PubMed]

20. Artero S, Ancelin ML, Portet F, Dupuy A, Berr C, Dartigues JF, Tzourio C, Rouaud O, Poncet M, Pasquier F, Auriacombe S, Touchon J, Ritchie K. Risk profiles for mild cognitive impairment and progression to dementia are gender specific. J Neurol Neurosurg Psychiatry. 2008;79:979–984. [PubMed]

21. Goldstein G, McCue M, Rogers J, Nussbaum PD. Diagnostic differences in memory test based predictions of functional capacity in the elderly. Neuropsychol Rehabil. 1992;2:307–317.

22. Bell-McGinty S, Podell K, Franzen M, Baird AD, Williams MJ. Standard measures of executive function in predicting instrumental activities of daily living in older adults. Int J Geriatr Psychiatry. 2002;17:828–834. [PubMed]

23. Cahn-Weiner DA, Boyle PA, Malloy PF. Tests of executive function predict instrumental activities of daily living in community-dwelling older individuals. Appl Neuropsychol. 2002;9:187–191. [PubMed]

24. Farias ST, Mungas D, Reed B, Haan MN, Jagust WJ. Everyday functioning in relation to cognitive functioning and neuroimaging in community-dwelling Hispanic and non-Hispanic older adults. J Int Neuropsychol Soc. 2004;10:342–354. [PMC free article] [PubMed]

25. Royall DR, Palmer R, Chiodo LK, Polk MJ. Executive control mediates memory's association with change in instrumental activities of daily living: The Freedom House Study. J Am Geriatr Soc. 2005;53:11–17. [PubMed]

26. Schmitter-Edgecombe M, Woo E, Greeley DR. Characterizing multiple memory deficits and their relation to everyday functioning in individuals with mild cognitive impairment. Neuropsychology. 2009;23:168–177. [PubMed]

27. Tomaszewski Farias S, Cahn-Weiner DA, Harvey DJ, Reed BR, Mungas D, Kramer JH, Chui H. Longitudinal changes in memory and executive functioning are associated with longitudinal change in instrumental activities of daily living in older adults. Clin Neuropsychol. 2009;23:446–461. [PMC free article] [PubMed]

28. Park KW, Pavlik VN, Rountree SD, Darby EJ, Doody RS. Is functional decline necessary for a diagnosis of Alzheimer's disease? Dement Geriatr Cogn Disord. 2007;24:375–379. [PubMed]

29. Tam CW, Lam LC, Chiu HF, Lui VW. Characteristic profiles of instrumental activities of daily living in Chinese older persons with mild cognitive impairment. Am J Alzheimers Dis Other Demen. 2007;22:211–217. [PubMed]

30. Burton CL, Strauss E, Bunce D, Hunter MA, Hultsch DF. Functional abilities in older adults with mild cognitive impairment. Gerontology. 2009;55:570–581. [PubMed]

31. Aretouli E, Brandt J. Everyday functioning in mild cognitive impairment and its relationship with executive cognition. Int J Geriatr Psychiatry. 2010;25:224–233. [PMC free article] [PubMed]

32. Morris JC, Weintraub S, Chui HC, Cummings J, Decarli C, Ferris S, Foster NL, Galasko D, Graff-Radford N, Peskind ER, Beekly D, Ramos EM, Kukull WA. The Uniform Data Set (UDS): clinical and cognitive variables and descriptive data from Alzheimer Disease Centers. Alzheimer Dis Assoc Disord. 2006;20:210–216. [PubMed]

33. Pfeffer RI, Kurosaki TT, Harrah CH, Jr, Chance JM, Filos S. Measurement of functional activities in older adults in the community. J Gerontol. 1982;37:323–329. [PubMed]

34. Folstein MF, Folstein SE, McHugh PR. ‘Mini-mental state’. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189–198. [PubMed]

35. Rosen WG, Terry RD, Fuld PA, Katzman R, Peck A. Pathological verification of ischemic score in differentiation of dementias. Ann Neurol. 1980;7:486–488. [PubMed]

36. Teng E, Becker BW, Woo E, Knopman DS, Cummings JL, Lu PH: Utility of the Functional Activities Questionnaire for distinguishing mild cognitive impairment from very mild Alzheimer's disease. Alzheimer Dis Assoc Disord, in press. [PMC free article] [PubMed]

37. Weintraub S, Salmon D, Mercaldo N, Ferris S, Graff-Radford NR, Chui H, Cummings JL, DeCarli C, Foster NL, Galasko D, Peskind E, Dietrich W, Beekly DL, Kukull WA, Morris JC. The Alzheimer's Disease Centers' Uniform Data Set (UDS): the neuropsychologic test battery. Alzheimer Dis Assoc Disord. 2009;23:91–101. [PMC free article] [PubMed]

38. Wechsler D. Wechsler Memory Scale – Revised Edition: Manual. San Antonio: The Psychological Corporation; 1987.

39. Morris JC, Heyman A, Mohs RC, Hughes JP, van Belle G, Fillenbaum G, Mellits ED, Clark C. The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). 1. Clinical and neuropsychological assessment of Alzheimer's disease. Neurology. 1989;39:1159–1165. [PubMed]

40. Reitan RM, Wolfson D. The Halstead-Reitan Neuropsychological Test Battery. Theory and Clinical Interpretation. Tucson: Neuropsychology Press; 1989.

41. Wechsler D. Wechsler Adult Intelligence Scale – Revised Edition: Manual. San Antonio: The Psychological Corporation; 1981.

42. Kaplan E, Goodglass H, Weintraub S. Boston Naming Test. Philadelphia: Lea & Febiger; 1983.

43. Velicer WF, Jackson DN. Component analysis versus common factor analysis: some issues in selecting an appropriate procedure. Multivariate Behav Res. 1990;25:1–28.

44. Pereira FS, Yassuda MS, Oliveira AM, Forlenza OV. Executive dysfunction correlates with impaired functional status in older adults with varying degrees of cognitive impairment. Int Psychogeriatr. 2008;20:1104–1115. [PubMed]

45. Lezak MD, Howieson DB, Loring DW. Neuropsychological Assessment. ed 4. New York: Oxford University Press; 2004.

46. Teng E, Tingus KD, Lu PH, Cummings JL. Persistence of neuropsychological testing deficits in mild cognitive impairment. Dement Geriatr Cogn Disord. 2009;28:168–178. [PMC free article] [PubMed]

47. He J, Farias S, Martinez O, Reed B, Mungas D, Decarli C. Differences in brain volume, hippocampal volume, cerebrovascular risk factors, and apolipoprotein e4 among mild cognitive impairment subtypes. Arch Neurol. 2009;66:1393–1399. [PMC free article] [PubMed]

48. Boone KB, Victor TL, Wen J, Razani J, Ponton M. The association between neuropsychological scores and ethnicity, language, and acculturation variables in a large patient population. Arch Clin Neuropsychol. 2007;22:355–365. [PubMed]

49. Manly JJ, Jacobs DM, Touradji P, Small SA, Stern Y. Reading level attenuates differences in neuropsychological test performance between African American and White elders. J Int Neuropsychol Soc. 2002;8:341–348. [PubMed]

50. Luck T, Luppa M, Briel S, Riedel-Heller SG. Incidence of mild cognitive impairment: a systematic review. Dement Geriatr Cogn Disord. 2010;29:164–175. [PubMed]

51. Alladi S, Arnold R, Mitchell J, Nestor PJ, Hodges JR. Mild cognitive impairment: applicability of research criteria in a memory clinic and characterization of cognitive profile. Psychol Med. 2006;36:507–515. [PubMed]

52. Loewenstein DA, Acevedo A, Ownby R, Agron J, Barker WW, Isaacson R, Strauman S, Duara R. Using different memory cutoffs to assess mild cognitive impairment. Am J Geriatr Psychiatry. 2006;14:911–919. [PubMed]

53. Rountree SD, Waring SC, Chan WC, Lupo PJ, Darby EJ, Doody RS. Importance of subtle amnestic and nonamnestic deficits in mild cognitive impairment: prognosis and conversion to dementia. Dement Geriatr Cogn Disord. 2007;24:476–482. [PubMed]

54. Farias ST, Harrell E, Neumann C, Houtz A. The relationship between neuropsychological performance and daily functioning in individuals with Alzheimer's disease: ecological validity of neuropsychological tests. Arch Clin Neuropsychol. 2003;18:655–672. [PubMed]

55. Wadley VG, Okonkwo O, Crowe M, Ross-Meadows LA. Mild cognitive impairment and everyday function: evidence of reduced speed in performing instrumental activities of daily living. Am J Geriatr Psychiatry. 2008;16:416–424. [PubMed]

Articles from Dementia and Geriatric Cognitive Disorders are provided here courtesy of
Karger Publishers