Background and objectives: Chronic disorders such as diabetes mellitus type II and hypertension have been associated with cognitive decline in older adults. It is unclear whether adherence to antihypertensive and oral hypoglycemic agents impact cognitive health. The objectives are to study the association between adherence to antihypertensive and oral hypoglycemic agents and cognitive status in community-living older adults. Methods: We used data from a large representative sample of older adults (N=2,286) covered under a public drug insurance plan in Quebec and participating in Quebec's health survey on older adults (ESA-study) with a Mini-Mental State Examination (MMSE) score ≥22 at baseline (T1) and examined one year later (T2). Participants with hypertension and diabetes mellitus type II were identified according to criteria used in the Canadian Chronic Disease Surveillance System. Antihypertensive and oral hypoglycemic prescriptions delivered were ascertained via Quebec's pharmaceutical database (RAMQ). Medication adherence was calculated using the medication possession ratio as a continuous variable in the year prior to and following baseline interview. Multivariate linear regressions were used to study the percentage change in MMSE scores between interviews (T1,T2) as a function of adherence to antihypertensive and oral hypoglycemic agents (before and after T1) controlling for potential confounders. Results: In participants with diabetes mellitus type II only, adherence to oral hypoglycemics was not associated with a change in MMSE scores. In participants with hypertension only, the change in MMSE scores was associated with adherence to antihypertensives (β 1.23; 95%CI: 0.29-2.17). In participants with comorbid hypertension and diabetes mellitus type II, the change in MMSE scores was associated with adherence to both antihypertensive and oral hypoglycemic agents (β 0.75; 95%CI: 0.01-1.48). Conclusions: Adherence to oral hypoglycemic agents and antihypertensive agents among older adults with hypertension and comorbid diabetes mellitus type II can have a preserving effect on cognitive health in older adults. Further research on the long-term impact on cognition is recommended.
Keywords: cognition; diabetes mellitus type II; hypertension; medication adherence; oral hypoglycemic agents.