Hundreds of thousands of older people who take common drugs could be at increased risk of mental decline and death, research suggests.

A study of 13,000 people found risks from over-the-counter and prescription drugs, including some antihistamines, painkillers, blood thinners and eye drops for glaucoma.

Researchers say well-known side-effects of the drugs could have an impact on the brain, increasing the risk of decline and death.

Some of the most dangerous drugs are commonly available, including the antihistamines chlorphenamine (used in the brand Piriton) and promethazine (used in Phenergan), anti-depressants amitriptyline (used in several brands) and paroxetine (used in Seroxat) and the incontinence drug oxybutynin (used in Ditropan).

The study, published in the Journal of the American Geriatrics Society, forms part of the Medical Research Council's Cognitive Function and Ageing Studies project, which hopes to uncover risk factors for dementia. PA