Polypharmacy in people with dementia: a nationwide Danish study

Polypharmacy, particularly central nervous system (CNS)-active polypharmacy, is widespread in individuals with dementia and may accelerate cognitive decline and increase hospitalization and mortality risks. Identifying the extent and trends of polypharmacy is essential for optimizing medication use in this vulnerable population. We examined the prevalence, time trends, and adjusted odds of polypharmacy and CNS-active polypharmacy in older adults with dementia compared to those without dementia. The study was a series of nationwide cross-sectional population-based studies based on the national Danish registers. All Danish residents aged ≥ 65 years (N = 1,184,366) were included as of January 1, 2022, including 38,252 individuals with dementia. Dementia, along with somatic and psychiatric comorbidities, was identified through hospital diagnoses, while medication use was assessed based on filled prescriptions. Historical trends were examined from 2012 to 2022. Dementia was based on diagnoses or dementia-specific medication use. Polypharmacy was defined as concurrent use of ≥ 5 medications, and CNS-active polypharmacy as ≥ 3 CNS-active drugs (antidepressants, antipsychotics, antiepileptics, anxiolytics, hypnotics, or opioids). Age- and sex-standardized prevalences were calculated by direct standardization. Adjusted odds ratios (ORs) for polypharmacy and CNS-active polypharmacy were estimated using logistic regression. Among 1,184,366 individuals in 2022, 38,252 (3.2%) had dementia (59.4% female) with median age of 82 years (IQR, 77–87 years). Polypharmacy was identified in 56.2% of those with dementia, compared to 35.6% without dementia, fully adjusted OR, 1.47 (95% CI, 1.44–1.51). CNS-active polypharmacy was observed in 10.1% of individuals with dementia and 2.3% of those without, fully adjusted OR, 2.70 (95% CI, 2.59–2.81). Cardiovascular medications were the most frequently used among individuals with dementia experiencing polypharmacy. For CNS-active polypharmacy, antidepressants, opioids, and antipsychotics were most common. Between 2012 and 2022, polypharmacy prevalence in dementia declined from 65.1% to 56.2%, and CNS-active polypharmacy from 15.0% to 10.1%. Patterns differed by living situation with dementia being linked to higher polypharmacy in community-dwelling individuals but lower in nursing homes. While polypharmacy and CNS-active polypharmacy in dementia have declined over the past decade, likely influenced by targeted safer prescribing initiatives, they remain disproportionately high in individuals with dementia. The findings reinforce the need for continued interventions to support safe medication use in dementia care.