The apolipoprotein E epsilon 4 allele and the response to tacrine therapy in Alzheimer's disease

The objective of our study was to evaluate the effects of the apolipoprotei n E (ApoE) phenotype and gender on the response to tacrine treatment in Alz heimer's disease (AD). ApoE phenotyping was performed on 76 patients treate d with tacrine for AD. This group comprised 33 ApoE epsilon 4 allele carrie rs (epsilon 4+) and 43 non-epsilon 4 carriers (epsilon 4-). Patients were t reated blindly in relation to the ApoE phenotype, with incremental tacrine dosages ranging from 40 mg/day up to the highest dosage (160 mg) tolerated without side-effects. At least 6 weeks elapsed between each increase. Chang es in the scores for the Alzheimer Disease Assessment Scale-Cognitive Compo nent (ADAS-Cog) between baseline and each increment in dosage were assessed in the epsilon 4- and epsilon 4+ groups. The cut-off point for being consi dered as responsive to tacrine treatment was a 4-point decrease in the ADAS -Cog score. There was no tendency for the epsilon 4- carriers to respond better than th e epsilon 4+ carriers. When patients were stratified by gender, no differen ces were found between the effects of the treatment on men and women. Conse quently, these results do not support the hypothesis that the ApoE phenotyp e and gender are predictors of the response to tacrine in AD patients.