HEALTH NEWS: Over-the-counter sleep medicine is linked to dementia

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By Joely Phenes

Researchers have discovered a significant link between high use of anticholinergic drugs – including popular non-prescription sleep aids and the antihistamine Benadryl (diphenhydramine) – and increased risk of developing dementia and Alzheimer’s disease in older people.

Anticholinergics are a class of drug that blocks the action of the neurotransmitter acetylcholine in the brain and body. Although the link between raised risk of dementia and anticholinergics has been found before, the new study uses more rigorous methods – including over seven years of follow-up – to establish the strength of the link. By accessing pharmacy records, the researchers were also able to include non-prescription use of anticholinergics in their data. Other side effects, including drowsiness, constipation, retaining urine and dry mouth and eyes.

Research was done by a professor in the University of Washington School of Pharmacy in Seattle, reported their findings in JAMA Internal Medicine in January 2015.

“Older adults should be aware that many medications – including some available without a prescription, such as over-the-counter sleep aids – have strong anticholinergic effects.” says the professor named Shelly Grey.

Prof. Gray urges people not to stop their therapy based on the findings of this study – they should talk to their health care provider, and also tell them about all their over-the-counter drug use. “Health care providers should regularly review their older patients’ drug regimens – including over-the-counter medications – to look for chances to use fewer anticholinergic medications at lower doses,” she says.

If providers need to prescribe anticholinergics to their patients because they offer the best treatment, then “they should use the lowest effective dose, monitor the therapy regularly to ensure it’s working, and stop the therapy if it’s ineffective,” she adds. It is also the first study to show a dose-response effect, note the authors. That is, the higher the cumulative amount of drug taken, the higher the risk of developing dementia.

And another first for the study, is that it also shows that dementia risk linked to anticholinergics may persist long after people stop taking the drugs.

For their study, Prof. Gray and colleagues tracked nearly 3,500 men and women aged 65 and over with no dementia symptoms at the start of the study. The participants were part of the Adult Changes in Thought (ACT) study in Group Health, an integrated health care delivery system in Seattle.

To assess how much exposure the participants had to anticholinergic drugs, the researchers used computer records from the pharmacies that dispensed them.

From the pharmacy data they added up all the standard daily doses and worked out the cumulative anticholinergic exposure for each participant over the past 10 years. This was updated as participants were followed up for an average of 7 years. Over the period of the study, nearly 800 participants developed dementia.

Some of the ACT participants have agreed to have their brains autopsied after they die. This might reveal if taking anticholinergic medications is more likely to result in brain changes that are characteristic of people who develop Alzheimer’s disease.