Led by researchers at the University of East Anglia as part of the MRC’s Cognitive Function and Ageing Studies project, the study is described as the first systematic investigation into the long term health impacts of ‘anticholinergic activity’. This activity is a known potential side effect of many prescription and over the counter drugs. The activity affects the brain by blocking acetylcholine, a key neurotransmitter for communication between nerve cells.
In the two year UK study, around half of the 13,000 participants were found to use a medication with potential anticholinergic properties. Medications with the properties are commonly taken by older people for a variety of reasons; including treatments for depression, bladder or heart problems, as painkillers, epilepsy and asthma treatments, or as eyedrops for treating glaucoma.
By allocating the various drugs a score indicating the strength of its anticholinergic effect (from 0 for no effect, to 3 for severe), the study’s key findings were:
• 20% of participants taking drugs with a total score of four or more had died by the end of the study, compared with only 7% of those taking no anticholinergic drugs – the first time a link between anticholinergics and mortality has been shown.
• For every additional point scored, the odds of dying increased by 26%.
• Participants taking drugs with a combined score of five or more scored more than four 4% lower in a cognitive function test than those taking no anticholinergic medications – confirming evidence from previous smaller studies of a link between anticholinergics and cognitive impairment.
• The increased risks from anticholinergic drugs were shown to be cumulative, based on the number of anticholinergic drugs taken and the strength of each drug’s anticholinergic effect.
• Those who were older, of lower social class, and with a greater number of health conditions tended to take the most anticholinergic drugs.
Rebecca Wood, Chief Executive of Alzheimer’s Research UK said:
“This comprehensive study could have some far-reaching effects. The results underline the critical importance of calculated drug prescription. Further investigation needs to establish exactly how and why drugs with an anticholinergic effect might be increasing mortality. This might offer clues to influence safer drug design. It’s important for people prescribed medicines with an anticholinergic effect not to panic, but to discuss with their doctor the best possible personal treatment plan.
“Large cohort research is essential to understanding what might influence the prevalence of dementia in a population. These broad studies can be invaluable in shaping public health policy, yet funding for such research remains shamefully low. With the 820,000 people currently living with dementia set to increase drastically, research is the only answer and we must invest more now.”
Commenting for Alzheimer’s Research UK, Prof Simon Lovestone, Director of Research for King’s Health Partners, said:
“Older people are prescribed many drugs, as this study shows. Yet again some of these drugs have been shown to have adverse effects, including an association with cognitive decline. This is an important and very large study and although we cannot assume that the drugs are actually causing the increased decline, there is good reason to think they may be. This study has important clinical lessons for all doctors looking after older people.”
Alzheimer’s Research UK