Polypharmacy is associated with functional decline in Alzheimer's disease and Lewy body dementia

In dementia, a number of factors may influence functional decline in addition to cognition. In this study, we aimed to study the potential association of the number of prescribed medications with functional decline trajectories over a five-year follow-up in people diagnosed with mild Alzheimer's disease (AD) or Lewy Body dementia (LBD).

This is a longitudinal analysis of a Norwegian cohort study entitled "The Dementia Study of Western Norway". We included 196 patients newly diagnosed with AD (n=111) and LBD (n=85), followed annually for 5 years. We conducted linear mixed-effects models to analyse the association of the number of medications with functional decline measured by the Rapid Disability Rating Scale - 2.

The mean prescribed medications at baseline was 4.18∓2.60, for AD 3.92∓2.51 and LBD 4.52∓2.70. The number of medications increased during the follow-up; at year five the mean for AD was 7.28∓4.42 and for LBD 8.11∓5.16. Using more medications was associated with faster functional decline in AD (Est 0.04, SE 0.01, p-value 0.003) and LBD (Est 0.08, SE 0.03, p-value 0.008) after adjusting for age, sex, comorbidity, neuropsychiatric symptoms, and cognition. For each medication added during the follow-up, functional trajectories worsened by 1% for AD and 2% for LBD. The number of medications was not associated with cognitive decline.

We found that higher number of medications was related to a faster functional decline, both in AD and LBD. With disease progression, there was an increase in the number of medications. Prescription in dementia should be carefully assessed, possibly improving the functional prognosis.