Polypharmacy, drug-drug interactions, anticholinergic burden and cognitive outcomes: a snapshot from a community-dwelling sample of older men and women in northern Italy

Polypharmacy (PP) use is very common in older people and may lead to drug-drug interactions (DDIs) and anticholinergic burden (ACB) that may affect cognitive function. We aimed to determine the occurrence of PP, potential DDIs and ACB and their role in cognitive outcomes in an older population. Cross-sectional data from 636 community-dwelling adults (73.2 ± 6.0 SD, 58.6% women) participating in the NutBrain study (2019–2023) were analyzed. Participants were asked about their medication use, and data on potential DDIs and ACB were extracted. The associations of PP (≥ 5 drugs/day), potential DDIs, and ACB with mild cognitive impairment (MCI) and specific cognitive domains were assessed using logistic regression adjusted for confounders. Sex-stratified analysis was performed. Overall, 27.2% of the participants were exposed to PP, 42.3% to potential DDIs and 19% to cumulative ACB. Women were less exposed to PP and more exposed to ACB than men. In multivariate analysis, the odds of having MCI (24%) were three times higher in those with severe ACB (≥ 3) (OR 3.34, 95%CI 1.35–8.25). ACB was positively associated with poor executive function (OR 4.45, 95%CI 1.72–11.49) and specifically with the Frontal Assessment Battery and neuropsychological tests of phonological and semantic fluency. In sex-stratified analysis, ACB was statistically significantly associated with MCI and executive function in women and with memory in men. PP, potential DDIs and anticholinergics use are very common in community-dwelling older people. ACB exposure is associated with MCI, particularly with poor executive function. Clinicians are encouraged to be vigilant when prescribing anticholinergics. Trial registration: Trial registration number NCT04461951, date of registration July 7, 2020 (retrospectively registered, ClinicalTrials.gov).