Long-term and/or high-dose use of a class of medications used for hay fever, depression and other ills has been linked in a new study to a higher risk of dementia.
The drugs – called anticholinergics – include nonprescription diphenhydramine (Benadryl) and tricyclic antidepressants like doxepin (Sinequan). This class of medications also includes older antihistamines like chlorpheniramine (Chlor-Trimeton) and “antimuscarinic” drugs for bladder control, such as oxbutynin (Ditropan).
However, the study could only point to an association between the use of these drugs and a higher risk of dementia, it could not prove cause-and-effect. Also the relationship “did not occur at the lowest dosage range but did occur at higher dosages used long-term,” said Dr. Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in New York City.
The new study was led by Shelly Gray of the Group Health Research Institute-University of Washington. Her team explained that the anticholinergic class of medications work by blocking a neurochemical called acetylcholine in both the brain and body.
Manevitz noted that people “suffering from Alzheimer’s disease typically show a marked shortage of acetylcholine.”
The new study tracked outcome for more than 3,500 seniors who were followed for more than seven years. Gray’s group found that people who took at least 10 mg per day of Sinequan, 4 mg per day of Benadryl, or 5 mg per day of Ditropan for more than three years were at greater risk for developing dementia.
The study, published January 26 in JAMA Internal Medicine, is the first to link higher use of anticholinergic medications to increased risk of dementia, the researchers said. It is also the first to suggest that the dementia risk associated with these drugs may not be reversible even years after people stop taking them.
Drugs, both prescription and over-the-counter (OTC) are complex man-made chemical compounds. For most of them, the mechanism of action is unknown or poorly understood. The list of side effects and drug interactions is exhausting.
As noted above, anticholinergics block the formation of acetylcholine, a vital neurotransmitter in the brain and nervous system. In the peripheral nervous system, acetylcholine plays a role in skeletal, smooth, and cardiac muscle movement. In the central nervous system it is believed to be involved in learning, memory, and mood. It is not surprising that this class of drugs that impairs chemical pathways in the nervous system has detrimental effects on those pathways. Of real concern is the fact that these effects appear to be permanent and irreversible.
The Bottom Line:
Think twice before taking any medication, prescription or OTC. The negative effects could dramatically affect your quality of life. There are natural alternatives that are safe, effective, and readily available to treat almost any condition. Do a little homework before you take that drug.
Source: January 26, 2015 National Institutes of Health