Characterization of polypharmacy and potential drug-drug interactions in Mexican older adults with cognitive decline.

BACKGROUND: Mild cognitive impairment (MCI) and dementia are common in older adults with multiple chronic conditions. Polypharmacy is more frequent in these populations and may increase the risk of potential drug-drug interactions (pDDIs). Most evidence on polypharmacy-related adverse outcomes originates from high-income countries, whereas data from Mexico remain limited. We aimed to determine the frequency of polypharmacy and pDDIs in older adults with and without cognitive impairment. METHODS: A case-control study was conducted in 141 participants from Mexico, 47 cases, and 94 controls. Each patient's drugs were analyzed and classified using the first level of the Anatomical Therapeutic Chemical (ATC) classification. Polypharmacy was determined as the regular use of ≥5 drugs at the same time, and pDDIs using the Medscape Drug Interaction Checker. RESULTS: The polypharmacy prevalence was 27.6% among cases and 16.0% among controls (p = 0.101). Among cases, polypharmacy was associated with higher urea levels (OR = 1.02; 95% CI: 1.00-1.04; p = 0.016) and lower glomerular filtration rate (OR = 0.97; 95% CI: 0.96-0.99; p = 0.026). Individuals with cognitive impairment had a higher frequency and proportion of pDDIs (p = 0.011 and p = 0.014, respectively). CONCLUSION: Polypharmacy among older adults with cognitive impairment in Yucatán, Mexico, was lower than rates reported in high-income countries, possibly reflecting differences in healthcare access and medication availability. Nevertheless, cognitively impaired individuals showed frequent pDDIs and alterations in renal function biomarkers, associated with polypharmacy, indicating that clinically relevant medication risks persist despite lower medication burden.