Objective: To test for a possible effect of the apolipoprotein E epsilon 4 (APOE ε4) allele on memory performance and executive functioning (EF) in cognitively intact elderly.
Method: The authors studied 202 randomly selected and cognitively intact older adults (65+ years) of the Leipzig Research Center for Civilization Diseases Health Care Study. Intact global cognitive functioning was defined using a Mini-Mental Status Examination (MMSE) score ≥ 28. Performance in memory was assessed with the CERAD Word List and Constructional Praxis Recall, performance in EF with the Trail Making Test Part B (TMT-B). Multivariable linear regressions were used to evaluate the association between cognitive performance and APOE status, controlled for covariates.
Results: Among the cognitively intact older adults, 21.3% (n = 43) were carriers of the APOE ε4 allele. Carriers did not differ significantly from noncarriers in terms of age, gender, intelligence level, or performance in memory but showed a significantly lower TMT-B performance as a measure of EF (TMT-B M time/SD = 105.6/36.2 vs. 91.9/32.7 s; Mann-Whitney U = 4,313.000; p = .009). The association between lower TMT-B performance and APOE ε4 genotype remained significant in multivariable linear regression analysis. Similar findings were found for the subsample of those 78 elderly, who reached a perfect MMSE-score of 30.
Conclusions: A lower EF performance in cognitively intact older APOE ε4 allele carriers might be related to an early Alzheimer's dementia (AD) prodrome. In this case, a stronger focus on first subtle changes in EF may help to improve early AD detection in those being at genetic risk.
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