Effects of the Apolipoprotein E Genotype on the Therapeutic Response in Alzheimer’s Disease Patients in Taiwan

Background: This retrospective research was conducted to analyze the impact of the apolipoprotein (Apo) Eε4 gene on the clinical response to donepezil among Taiwanese patients with Alzheimer's disease (AD). Methods: Patients diagnosed with AD and treated with 5 mg of donepezil per day at the Neurologic Department of Kaohsiung Medical University Hospital from July 2003 to December 2013 were recruited as our study participants. Before treatment, the patients received neuropsychological tests, including the Mini-Mental State Examination (MMSE), the Cognitive Abilities Screening Instrument (CASI), the global Clinical Dementia Rating (CDR) scale, and the Clinical Dementia Rating Scale Sum of Boxes Score (CDR-SOB). Follow-up evaluation was performed every half year. Results: In total, 76 AD patients with a mean age of 75.4 years ± 8.4 years were eventually recruited for this study. Twenty patients (26.3%) were ApoEε4 positive. Kaplan?Meier survival estimates of the time to functional decline for the ApoEε4-negative and the ApoEε4-positive groups were compared. Logrank test results indicated that the ApoEε4-positive group had poorer treatment response with significant difference when function was measured using the CASI and global CDR (p = 0.017 and p < 0.010 respectively). After adjustment for age, sex, and educational attainment, the ApoEε4 status still affected the time to functional decline. Conclusion: In the Taiwanese population, ApoEε4 may be negatively associated with the treatment response in AD patients treated with donepezil. These findings suggest that a genotype test for ApoE in AD patients may facilitate therapeutic decision making by physicians and care-givers.