Anticholinergic drugs tracked about 2.6 times the odds of decline
In eight pooled studies of 320,906 older adults healthy at the start, the range ran from 1.09 to 6.29. Cochrane rated the certainty low.
What the study found
Cochrane graded the anticholinergic dementia evidence low certainty
Pooling eight studies and 320,906 older adults, cognitively healthy at the start, anticholinergic burden went with about 2.6 times the odds of later dementia or decline. The range runs from 1.09 to 6.29. Cochrane rated the certainty low: better evidence could move it substantially.
The caveat · All anticholinergics, not this drug
This measures anticholinergic burden as a whole, not diphenhydramine and not antihistamines. Only 8 of the 25 studies found could be pooled at all. The scales used to score that burden agree poorly with one another, so what is being measured is not the same thing from study to study.