Common drug effect ups elderly death risk: study
Jun 24, 2011, 10:35 a.m.
By Kate Kelland
LONDON (Reuters) - A side effect of many commonly used drugs, including antihistamines and antidepressants, appears to increase the risk of reduced brain function and early death in older people, according to a study published on Friday.
Scientists from Britain's University of East Anglia who led the work said the findings showed it was vital for doctors to regularly review drugs taken by elderly patients to ensure the cumulative risks of side-effects did not outweigh the benefits.
"Our results show a potentially serious effect on mortality," Chris Fox, of UEA's Norwich Medical School, told reporters at a briefing in London.
The study, published in the Journal of the American Geriatrics Society, is the first systematic investigation into the long-term impact of anticholinergic activity -- a known potential side-effect of many prescription and over-the-counter drugs which affects the brain by blocking a key neurotransmitter called acetylcholine.
Many common medicines -- including the antihistamine Piriton and antidepressants brands Elavil, Tryptizol, Laroxyl and Anafranil -- have some anticholinergic effect and many are frequently taken by older people.
"One of the issues is that as we age, we tend to be prescribed more medicines which have an anticholinergic effect, increasing the overall burden," said Ian Maidment, a mental health pharmacist in Britain's National Health Service (NHS).
The researchers devised a ranking system which they called the AntiCholinergic Burden (ACB) score for the anticholinergic effects of more than 80 common prescription and over-the- counter drugs. They assigned them scores of 0 for no effect, 1 for mild effect, 2 for moderate effect and 3 for severe effect.
They then used this system to analyze more than 13,000 British men and women aged 65 and over for a two-year period.
They found that 20 percent of participants taking drugs with a total ACB of four or more had died by the end of the two-year study, compared with only 7 percent of those taking no anticholinergic drugs. For every extra ACB point, the odds of dying increased by 26 percent, they found.
Those taking drugs with a combined ACB of five or more scored more than 4 percent lower in a cognitive function tests than those taking no anticholinergic drugs -- a finding that confirmed evidence from previous smaller studies of a link between anticholinergics and mental decline.
And the increased risks from taking anticholinergic drugs were found to be cumulative, based on the number of medicines taken and the strength of each drug's anticholinergic effect.
"It's important to scrutinize medications given to older people very carefully to try to minimize harm as well as gain the desired benefit," said Carol Brayne of the University of Cambridge, who also worked on the study.
The researchers said other medications with the ABC impact included tranquilizers such as trifluoperazine, sometimes known by the brand name Stelazine, the heart drug nifedipine which is sold in extended release form by Mylan and Bayer, painkillers such as codeine, the common asthma treatment beclometasone, and the epilepsy drug Carbamazepine, sold as Carbatrol by Shire.
Fox said that, wherever possible, doctors should "avoid prescribing multiple drugs with anticholinergic effects."
Susanne Sorensen, head of research at the Alzheimer's Society, who was not involved in the study, said its findings must be taken seriously, particularly since loss of cognitive function can be a precursor to the mind-robbing Alzheimer's disease and other forms of dementia.
SOURCE: http://bit.ly/ktyLS3 Journal of the American Geriatrics Society, online June 24, 2011.