Drugs that fall into this class include tricyclic antidepressants, antihistamines, meds used to treat overactive bladders, and -- of special concern to me -- over-the-counter (OTC) sleep aids. A new study published in January shows that all these drugs may increase the risk of dementia and Alzheimer's.
The neurotransmitter that these drugs block -- acetylcholine -- helps transmit messages in the nervous system. It's linked to learning and memory, and it also stimulates muscle contractions.
"We have known for some time that even single doses of these [anticholinergic] medications can cause impairment in cognition, slower reaction time, and reduced attention and ability to concentrate," said Shelley Gray, the study's principal author and pharmacy professor at the University of Washington in Seattle.
At first, "the thinking was that these cognitive effects were reversible when you stopped taking the medication," said Gray. But her study found a link between heavier use of these medications and dementia, "a non-reversible, severe form of cognitive impairment."
Gray's team tracked nearly 3,500 men and women 65+ who'd taken part in Adult Changes in Thought (ACT), a long-term study conducted by the University of Washington and Group Health, a Seattle healthcare system. The researchers used Group Health's pharmacy records to determine all the drugs, prescription and OTC, that participants had taken during the previous ten years. On average, their health was monitored for about seven years.
Many drugs have stronger effects on seniors. With age, the kidneys and liver clear drugs from the system more slowly, so drug levels in the blood remain higher longer. People also gain fat and lose muscle mass with age, which changes the way the body processes drugs. In addition, older people tend to take more prescription and OTC medications, each of which could suppress, enhance, or complicate the effectiveness of the others.
The Dangerous Drugs
In 2008, geriatrician Malaz Boustani at the Indiana University School of Medicine developed the anticholinergic burden scale (ACB), which places these drugs into three categories according to the severity of their effects on the mind. It's a good idea to steer clear of drugs in ACB category #3, which indicates the greatest risk. Here are some of those ACB category #3 meds popular with seniors:
Tricyclic Antidepressants: ABC#3 drugs include amitriptylines like Elavil, desipramine (Norpramin), doxepin (Sinequan), imipramine (Tofranil), nortriptyline (Pamelor). and paroxetine (Paxil).
Antihistamines (H-1 Blockers): Drugs rated ABC#3 include chlorpheniramine (Chlor-Trimeton), diphenhydramine (Benadryl), hydroxyzine (Atarax, Vistaril).
Overactive Bladder: The high-risk drugs here include oxybutynin (Ditropan), propantheline (Pro-Banthine), and tolterodine (Detrol).
Antiparkinson Medications: benztropine (Cogentin), trihexyphenidyl (Artane)
My Concerns About the Study
For years, I used and eventually abused Tylenol PM, especially when I added some Ambien to the mix. That misuse led to what I've dubbed the "Summer from Hell," which proved to be the wake-up call I needed.
I haven't used Ambien since then, and I've rarely used Tylenol PM or other traditional sleep aids. I've found that the serotonin booster 5-HTP is effective in warding off insomnia, as well as depression and constipation.
But the new study clearly suggests that my years of using the anticholinergic Tylenol PM may well carry a lasting effect: an increased risk of dementia.