Drugs commonly used by older people could increase the risk of mental decline and even death, according to new research.
The over-the-counter and prescription drugs are used by hundreds of thousands of older people in the UK. They include some antihistamines, painkillers, blood thinners and eye drops for glaucoma.
Scientists at the University of East Anglia led the study of 13,000 people aged 65 and over, analysing more than 80 drugs for anticholinergic activity - a potential side-effect that causes a key neurotransmitter in the brain called acetylcholine to be blocked.
The drugs were ranked from one to three depending on anticholinergic activity. Those that scored one had a mild effect and two a moderate effect - while those scoring three raised the most serious concern.
The risk of harmful side-effects increased for patients taking a combination of drugs. The researchers said the threshold for damage in patients was a total score of about four.
Some drugs ranked as the most dangerous are widely 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).
Professor James Goodwin, Head of Research at Age UK, said:
'Age UK welcomes the findings of this study which looks at an important area for the health of older people.
'Further research will be important in having a greater understanding of how medication interacts with the body and affects things like cognition, and will help healthcare professionals to be as informed as possible about the types of medication and dose they offer patients.
'However, at this stage we would urge people to continue to take their medication and to talk to their physician if they have any questions or concerns. Physicians should continue to review their patients regularly, particularly as older people often take multiple prescriptions.
Source Age UK