Pre-Morbid IQ Moderates the Relationship between Cognitive Performance and Performance-Based Functional Status in Older Adults

ABSTRACT

Objectives: The current study sought to evaluate the relationship between cognitive performance and Instrumental Activities of Daily Living (IADL) performance in a population of community dwelling older adults, and assess to what extent this relationship is moderated by cognitive reserve (Premorbid-IQ)

Methods: 123 community-dwelling older adults completed a general cognitive assessment, a word-reading based premorbid-IQ estimate (PMIQE) measure, and the performance-based Direct Assessment of Functional Status, Revised (DAFS-R). Moderated regression analysis was used to assess the influence of PMIQE on the relationship between cognitive performance and IADLs.

Results: There was a significant main effect of cognitive performance on IADLs, and no main effect of PMIQE on functional IADLs. There was a significant moderating effect of PMIQE on the relationship between cognitive performance and IADLs performance, such that at higher levels of PMIQE, cognitive performance scores became slightly less predictive of weaknesses in IADLs.

Conclusions: Results suggest that for individuals with high reserve, assessment of cognitive performance alone may not be robust a predictor of IADLs functioning.

Clinical implications: In estimating functional abilities as a consequence of cognitive performance, consideration should be given to premorbid-IQ/cognitive reserve.

KEYWORDS:

• Aging
• cognitive function
• premorbid IQ
• cognitive reserve
• functional independence
• instrumental activities of daily living

Clinical Implications

• There is a meaningful relationship between cognition, pre-morbid-IQ and functional status in late life

• When assessing cognitive performance to estimate/predict functional independence in IADLS, it is prudent to consider how individuals’ pre-morbid functioning may influence the expression of functional impairment

• Cognitive reserve may buffer the expression of functional impairment in IADLs, whereas for individuals with lower cognitive reserve, cognitive deficits on neuropsychological evaluations are more predictive of associated functional impairment.

Disclosure statement

No potential conflict of interest was reported by the authors.

Human subjects research protocol approval

University of Georgia IRB Protocol# 2012105162, UGA IRB # MOD00002223