Common Drugs Linked to Alzheimer's Disease

New study finds a connection between drugs (both Rx and over-the-counter) and Alzheimer's.

January 27, 2015
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Common medications, ranging from antidepressants to over-the-counter antihistamines, have been linked to dementia, including Alzheimer's disease, according to recent research published in the journal JAMA Internal Medicine.

The drugs in question are anticholinergic medications. These drugs include non-prescription diphenhydramine (brand name Benadryl), tricyclic antidepressants like doxepin (Sinequan), first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan).

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The study tracked the anticholinergic exposure of nearly 3,500 seniors from 1994 to 2012 with follow-ups every two years. The study estimated that people taking at least 10 milligrams (mg) per day of doxepin, 4 mg per day of chlorpheniramine, or 5 mg per day of oxybutynin for more than three years would be at greater risk for developing dementia.

Not only did the researchers find that these effects are dose-dependent (the more anticholinergic medication you take, the higher your risk for developing dementia), but the findings also suggest that the effects may not be reversible, even after you discontinue use of the drug.

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Importantly, drugs with anticholinergic effects can be available without a prescription, points out Shelly Gray, PharmD, MS, author of the report and professor, vice-chair of curriculum and instruction, and director of the geriatric pharmacy program at the University of Washington School of Pharmacy.

"Healthcare 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 you have a condition that necessitates medical intervention, ask your doctor about non-anticholinergic alternatives. Gray says that these substitutes include a selective serotonin reuptake inhibitor (SSRI) like citalopram (Celexa) or fluoxitene (Prozac) for depression and a second-generation antihistamine like loratadine (Claritin) for allergies.

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"If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient," Dr. Gray said, "they should use the lowest effective dose, monitor the therapy regularly to ensure it's working, and stop the therapy if it's ineffective."

While there are non-anticholinergic alternatives for some of these drugs, most drugs (whether anticholinergic or not) cause nutrient deficiencies, resulting in nasty side effects. "Drugs are advertised to fix one problem, but in reality (as opposed to what's on TV), they often manage to disrupt other aspects of cellular function," says Suzy Cohen, RPh, author of Drug Muggers. "That's common knowledge in my circle of healthcare practitioners. Unfortunately, it's not common knowledge to most people."

Cohen explains that the listed side effects of medications are the symptoms that occur due to nutrient deficiencies caused by that drug. "Since I became a pharmacist, I've seen an exponential rise in the use of medications, many of them helpful and necessary, but some of them dangerous and dubious," she says. "And I know that when drugs deplete the body of essential nutrients, it's easy to replace them by taking the right kinds of supplements."

Here are the possible deficiencies associated with the three common conditions treated with anticholinergic drugs.

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Depression
In addition to putting you at risk for Alzheimer's, Cohen says that tricyclic antidepressants can also rob your body of coenzyme Q10, glutathione, melatonin, riboflavin, and selenium. The alternative suggested by Gray, SSRIs, can steal folate, melatonin, and selenium.

Cohen points out that depression itself can stem from deficiencies of B vitamins, coenzyme Q10, magnesium, or vitamin C, so before starting down the path of stealing more nutrients from your body with antidepressants, talk with your doctor about your diet or adding these supplements to your health regimen.  

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Allergies
There are plenty of natural remedies for allergies, so unless your condition is life threatening, you may want to give up antihistamines, as Cohen says they can rob your body of melatonin, your body's sleep hormone. Instead, Cohen says that vitamin C may help lower high histamine levels.

Bladder Control
Oxybutynin is a medication for urinary incontinence. To minimize your dose, talk to your doctor about adding horsetail tea. "This herbal remedy helps people with bladder issues," says Cohen. "Horsetail is the name given to the herb Equisetum arvense. I feel confident that this tea can be combined safely with urinary incontinence medications because it causes enhanced effects, which I consider beneficial in this case."