High use of common drugs linked to dementia, Alzheimer's

Date: Jan-27-2015 A new study has found 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.

Many medications - including some popular over the counter drugs - have strong anticholinergic effects.

Anticholinergics are a class of drug that blocks the action of the neurotransmitter acetylcholine

in the brain and body.

This can lead to many side effects, including drowsiness, constipation, retaining urine and dry

mouth and eyes.

The researchers, led by Shelly Gray, a professor in the University of Washington School of

Pharmacy in Seattle, report their findings in JAMA Internal Medicine.

Prof. Gray says:

"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."

People should not stop their therapy but talk to their health care provider

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.

Although the link between raised risk of dementia and anticholinergics has been found before, the

new study uses more rigorous methods - including over 7 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.

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.

Taking anticholinergics for more than 3 years linked to higher dementia risk

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.

The results showed that the most commonly used medications were tricyclic antidepressants (for

example, doxepin or Sinequan), first-generation antihistamines (chlorpheniramine, Chlor-Trimeton),

and antimuscarinics for bladder control (oxybutynin, Ditropan).

The researchers estimated that people taking at least 10 mg per day of doxepin, 4 mg per day of

chlorpheniramine, or 5 mg per day of oxybutynin for more than 3 years would be at greater risk for

developing dementia.

Prof. Gray says there are alternative non-anticholinergic drugs for doxepin and chlorpheniramine.

For example, to treat depression there are the selective serotonin re-uptake inhibitor (SSRI) like

citalopram (Celexa) or fluoxetine (Prozac). And there are second generation antihistamines like

loratadine (Claritin) for allergies.

However, while there are not many alternatives to oxybutynin for increasing bladder control, she

suggests behavioral changes may be an option.

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.

Funds for the study came from the NIH's National Institute on Aging and the Branta

Foundation.

Meanwhile, Medical News Today recently learned how a team of scientists and engineers are

developing an MRI method for non-invasive, early detection of

Alzheimer's disease. They have so far shown that it works in animals. The new brain imaging

method detects the toxin that leads to Alzheimer's disease before typical symptoms appear.

Written by Catharine Paddock PhD

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.