Background: Asthma and chronic obstructive pulmonary disease (COPD) are common comorbidities in persons with Alzheimer's disease (AD). However, pharmacotherapy of these diseases may have opposite mechanisms of action; anticholinergics in asthma/COPD and acetylcholinesterase inhibitors (AChEI) in AD.
Objective: To investigate whether existing asthma/COPD affects the choice of AD medication, and the survival of the patients with AD.
Methods: In this retrospective cohort study, data from the MEDALZ-study, which includes all community-dwelling persons with AD during 2005-2011 in Finland (n = 70718) was utilized. Persons with asthma/COPD (N = 7211) were defined as having a special reimbursement for asthma/COPD, or long-term use (≥250 days) of inhaled anticholinergics, inhaled corticosteroids, or leukotriene antagonists during the year before AD diagnosis. We compared persons with and without asthma/COPD regarding the choice of the initial antidementia medication (AChEI versus memantine) with logistic regression and mortality with Cox regression model during the follow-up (up to end of 2015).
Results: Memantine was favored over AChEIs as first-line treatment to AD in persons with asthma/COPD compared to those without asthma/COPD (odds ratio 1.23, 95% confidence interval (CI) 1.15-1.31). Memantine was also more commonly used among those who used multiple asthma/COPD medications (7.9% of memantine initiators used ≥3 asthma/COPD medications compared with 5.5% of those who initiated with AChEI). Mortality was higher in persons with asthma/COPD compared to those without asthma/COPD (adjusted hazard ratio 1.10, 95% CI 1.07-1.13).
Conclusion: More frequent use of memantine instead of AChEI may result from an attempt to prevent possible worsening of asthma/COPD by AChEIs. Vulnerable persons with both AD and asthma/COPD need individually assessed pharmacotherapy for their medical conditions.
Keywords: Alzheimer’s disease; anticholinergics; asthma; cholinesterase inhibitors; chronic obstructive pulmonary disease; dementia; older person.