Interaction between apolipoprotein E genotype and hypertension on cognitive function in older women in the Nurses’ Health Study

OBJECTIVE: To examine the interaction between APOE genotypes and both treated and untreated hypertension on cognitive function in an updated analysis of Nurses’ Health Study (NHS) data. DESIGN: At baseline (1995–2001) and 3 biennial follow-up assessments over ~6 years, cognitive function was assessed. SETTING AND PARTICIPANTS: 8300 NHS participants aged 70+ years underwent a cognitive battery, which comprised 6 tests including the Telephone Interview for Cognitive Status (TICS) and tests of verbal memory, category fluency, and working memory. MEASURES: We estimated the mean differences in average cognitive scores across up to 4 assessments using multiple linear regression. We also tested for interaction between APOE e4 allele carrier status and hypertension overall, as well as for apparently untreated and treated hypertension. RESULTS: We confirmed that, compared with those with APOE e3/3 genotype, APOE e4 allele carriers scored lower by 0.55 units on the average TICS score (95%CI:-0.67,-0.43). We also observed a significantly worse average TICS score among women with untreated hypertension compared with women without hypertension (difference = -0.23, 95%CI:-0.37,-0.09), while no significant difference was observed for women with treated hypertension. Significant interaction was detected between the APOE e4 allele and untreated hypertension (p-int = 0.02 for the TICS; p-int = 0.045 for global score), but not with treated hypertension. Specifically, compared with normotensive women with the APOE e3/3 genotype, APOE e4 allele carriers with treated hypertension scored lower by 0.50 units (95%CI:-0.69,-0.31); however, the APOE e4 allele carriers with untreated hypertension scored lower by 1.02 units on the TICS score (95%CI:-1.29, -0.76). This interaction of APOE e4 and untreated hypertension was also consistently observed for the global score. CONCLUSIONS: Women with hypertension and at least one APOE e4 allele had worse average cognitive function compared with women without hypertension with the e3/3 genotype; this difference was amplified among APOE e4 allele carriers with untreated hypertension.