April 20, 2016 -- Older people who take certain medicines to treat conditions like urinary incontinence, depression, asthma, allergies, and sleeping problems should be warned that their use may bring a higher risk of dementia, scientists say.

A small Indiana University study found that people using "anticholinergic medications" did worse on thinking-related tests and had smaller brain sizes than those who didn't take them.

The researchers say that although a link has been found before, this might be the first time that their effect at blocking a brain chemical called acetylcholine has been implicated.

But the study showed an association, and it can't prove these drugs cause dementia.

See a list of drugs the researchers studied.