The Effect of the ApoE Genotype on the Association Between Head Circumference and Cognition

• Published in: The American journal of geriatric psychiatry Vol. 16; no. 10; pp. 819 - 825
• Main Authors: Kim, Kyung Ran, M.D, Lee, Kang Soo, M.D, Kim, Eun A., M.D., M.P.H., Ph.D, Cheong, Hae-Kwan, M.D., Ph.D, Oh, Byoung Hoon, M.D, Hong, Chang Hyung, M.D., Ph.D
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01-10-2008; Elsevier Limited
• Subjects: Aged; Aging - psychology; Alzheimer Disease - genetics; Analysis of Variance; ApoE genotype; Apolipoprotein E4 - genetics; Apolipoproteins E - genetics; Body Mass Index; Brain - anatomy & histology; Brain - growth & development; brain reserve; cognition; Cognition - physiology; Educational Status; elderly; Factor Analysis, Statistical; Female; Genotype; Head - anatomy & histology; Head circumference; Humans; Internal Medicine; K-MMSE; Korea; Male; Middle Aged; Regression Analysis; Korea; ApoE genotype; cognition; K-MMSE; elderly; brain reserve; Head circumference
• ISSN: 1064-7481; 1545-7214
• DOI: 10.1097/JGP.0b013e3181800551

Objectives The aim of this study was to examine the effect of the ApoE genotype on the association between head circumference (HC) and cognition. Design Cross-sectional factorial design in which Korean version of Mini Mental State Examination (K-MMSE) score was the dependent variable with ApoE4 status as one factor and HC as the other. Settings A longitudinal cohort study of the Korea Health 21 R&D Project Clinical Research Center for Dementia. Participants A total of 1,902 Koreans (599 men and 1303 women) aged over 60 years. Measurements Cognitive function was assessed by the K-MMSE. HC and ApoE genotyping were carried out on all subjects. Results The HC was correlated with the K-MMSE scores (r = 0.22, df = 1,525, p < 0.01), age (r = −0.11, df = 1,521, p < 0.01), educational level (r = 0.30, df = 1,525, p < 0.01), height (r = 0.50, df = 1,384, p < 0.01), and weight (r = 0.49, df = 1,445, p < 0.01). On analysis of covariance, the interaction of ApoE with HC on K-MMSE was observed after adjusting for the age, sex, educational level, height, and weight (F = 2.527, df = 4, 1, 364, p = 0.039). A test of simple main effect according to ApoE status showed that, in the ApoE ε4(−) group, the mean of K-MMSE between HC quintile was not different (F = 0.517, df = 4, 1,148, p = 0.723). But in the ApoE ε4(+) group, the mean of K-MMSE between HC quintile was significantly different. (F = 4.163, df = 4, 211, p = 0.003). Conclusion All these findings suggest the possibility that the presence of ApoE ε4 affects cognitive function only when the brain reserve is low. In other words, these findings support the structural “brain reserve hypothesis,” and the effects are more pronounced in genetically predisposed individuals.