Cognitive Reserve, Brain Reserve, APOEɛ4, and Cognition in Individuals with Subjective Cognitive Decline in the SILCODE Study

Article type: Research Article

Authors: Yang, Kun^{a; 1} | Chen, Guanqun^{b; d; 1} | Sheng, Can^b | Xie, Yunyan^b | Li, Yuxia^e | Hu, Xiaochen^f | Sun, Yu^{b; *} | Han, Ying^{b; c; d; *}

Affiliations: [a] Department of Evidence-based Medicine, Xuanwu Hospital of Capital Medical University, Beijing, China | [b] Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China | [c] Center of Alzheimer’s Disease, Beijing Institute for Brain Disorders, Beijing, China | [d] National Clinical Research Center for Geriatric Disorders, Beijing, China | [e] Central Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, China | [f] Department of Psychiatry and Psychotherapy, University of Cologne, Medical Faculty, Cologne, Germany

Correspondence: [*] Correspondence to: Prof. Ying Han, Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China. Tel.: +86 10 83167306; E-mail: hanying@xwh.ccmu.edu.cn. Yu Sun, Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China. E-mail: wuyou91@126.com.

Note: [1] These authors contributed equally to this work.

Abstract: Background:Cognitive reserve (CR) and brain reserve (BR) could offer protective effects on cognition in the early stage of Alzheimer’s disease (AD). However, the effects of CR or BR on cognition in individuals with subjective cognitive decline (SCD) are not clear. Objective:To explore the effects of CR and BR on cognition in subjects with SCD. Methods:We included 149 subjects from the Sino Longitudinal Study on Cognitive Decline (SILCODE) study. Education was used as a proxy for CR, and head circumference was used as a proxy for BR. Multiple linear regression models were conducted to examine the effects of CR and BR on cognitive scores. Furthermore, we assessed differences in effects between APOE ɛ4 carriers with SCD (n = 35) and APOE ɛ4 non-carriers with SCD (n = 114) and linear trends among 4 reserve levels (low BR/CR, high BR/low CR, low BR/high CR, and high BR/high CR). Results:Both CR and BR had independent positive effects on multiple cognitive measures in SCD participants, and the effects of CR were greater than those of BR. CR has positive effects on cognitive measures in both APOE ɛ4 carriers and non-carriers with SCD. However, the positive effects of BR on cognitive measures were observed in APOE ɛ4 non-carriers with SCD but not in APOE ɛ4 carriers with SCD. Furthermore, there was a linear trend toward better cognitive performance on all cognitive measures in the BR+/CR+ group, followed by the BR–/CR+, BR+/CR–, and BR–/CR–groups. Conclusion:This study suggests that both CR and BR have the potential to delay or slow cognitive decline in individuals with SCD.

Keywords: Alzheimer’s disease, Apolipoprotein E, brain reserve, cognition, cognitive reserve, dementia, education, head circumference, reserve, subjective cognitive decline

DOI: 10.3233/JAD-200082

Journal: Journal of Alzheimer's Disease, vol. 76, no. 1, pp. 249-260, 2020