An investigation of psychoactive polypharmacy and related gender-differences in older adults with dementia: a retrospective cohort study

BACKGROUND: Older adults living with dementia may express challenging responsive behaviours. One management strategy is pharmacologic treatment though these options often have limited benefit, which may lead to multiple treatments being prescribed. METHODS: The aim of the present study was to describe psychoactive medication polypharmacy and explore factors associated with psychoactive polypharmacy in a cohort of older adults living with dementia in Nova Scotia, Canada, including a gender-stratified analysis. This was a retrospective cohort study of those aged 65 years or older with a recorded diagnosis of dementia between 2005 and 2015. Medication dispensation data was collected from April 1, 2010, or dementia diagnosis (cohort entry) to either death or March 31, 2015 (cohort exit). Psychoactive medication claims were captured. Psychoactive medication polypharmacy was defined as presence of three or more psychoactive prescription medications dispensed to one subject and overlapping for more than 30 days. Psychoactive polypharmacy episodes were described in duration, quantity, and implicated medications. Regression analysis examined factors associated with experience and frequency of psychoactive polypharmacy. All analysis were stratified by gender. RESULTS: The cohort included 15,819 adults living with dementia (mean age 80.7 years; 70.0% female), with 99.4% (n = 15,728) receiving at least one psychoactive medication over the period of follow-up. Psychoactive polypharmacy was present in 19.3% of the cohort. The gender specific logistic regressions demonstrated that for both men and women a younger age was associated with an increased risk of psychoactive polypharmacy (women: OR 0.97, 95%CI[0.96, 0.98], men: OR 0.96, 95%CI[0.95, 0.97]). Men were less likely to experience psychoactive polypharmacy if their location of residence was urban (OR 0.86, 95%CI[0.74, 0.99]). There was no significant association between location of residence (urban or rural) and psychoactive polypharmacy for women living with dementia. Antidepressants were the most dispensed medication class, while quetiapine was the most dispensed medication. CONCLUSIONS: This study suggests that of adults living with dementia those of younger ages were more likely to experience psychoactive polypharmacy and that men living with dementia in rural locations may benefit from increased access to non-pharmacological options for dementia management. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-023-04353-8.