Apparently there is an association between regular use of anticholinergic drugs and the development of Alzheimer disease.
Strong Link Found Between Dementia, Common Anticholinergic Drugs • 2015 Apr 30 • Cynthia Fox • Drug Discover & Development
Three years of taking either daily Benadryl, Advil PM, Tylenol PM, or Motrin PM… is associated with about a ten percentage point increase in the probability of experiencing dementia or Alzheimer’s compared to no use.
Cumulative Use of Strong Anticholinergics and Incident Dementia A Prospective Cohort Study • 2015 Mar • Gray et al • JAMA Internal Medicine • The JAMA Network
Alzheimer disease is associated with the degeneration of cholinergic neurons, which is why acetylcholinesterase inhibitors are used to palliate symptoms (although cholinergic hypothesis has been called into question.)
Since Alzheimer dementia does not appear to be a straightforward case of degeneration of cholinergic neurons, I am skeptical there is a direct relationship between anticholinergic use and Alzheimer dementia.
I do wonder how much insomnia factors into the equation. Sleeping problems are also linked with an increased risk of dementia.
And while anticholinergics can put you to sleep, they don’t promote a normal sleep cycle.
Likewise, people with allergic rhinitis, depression, and urinary incontinence are likely to have disturbed sleep and to take anticholinergic medications as well.