Over-the-counter sleeping aids and hay-fever treatments can increase the risk of Alzheimer's, a study says.
The sleeping aid Nytol and anti-allergy pills Benadryl and Piriton all belong to a class of medication highlighted in a warning from researchers.
Each of these drugs has "anticholinergic" blocking effects on the nervous system that are said to raise the likelihood of developing Alzheimer's and other forms of dementia significantly at higher doses over several years.
Other drugs on the risk-list include older "tricyclic" antidepressants such as doxepin, and the bladder control treatment Ditropan.
Many of these medicines are taken by vulnerable older people, according to the scientists, who say their findings have public health implications.
