The 54% figure is for all anticholinergics, not antihistamines
The study most cited for the link followed 3,434 adults over 65 for seven years and reports no separate figure for antihistamines, which were 17.2% of the exposure.
What the study found
The 54% dementia figure covers every anticholinergic drug at once
The study most cited for an antihistamine-and-dementia link reports no separate figure for antihistamines. Across 3,434 adults over 65 followed seven years, the heaviest users of any strong anticholinergic drug had a 54% higher rate of dementia. Antihistamines were 17.2% of that exposure.
The caveat · The pills may mark early dementia
The conditions these drugs treat, insomnia and low mood among them, are early signs of dementia themselves, so the drug may be marking the illness rather than causing it. Dropping the last twelve months of use blunts that without removing it. One health system in Seattle, shop-bought use only partly captured.
What we don't know
The conditions these drugs treat, insomnia and low mood among them, are early signs of dementia themselves, so the drug may be marking the illness rather than causing it. Dropping the last twelve months of use blunts that without removing it. One health system in Seattle, shop-bought use only partly captured.