A new study released this week has found a correlation between four popular medications and the later development of dementia in those regularly using them. According to the study, the drugs are found in commonly used over-the-counter and prescription drugs including antihistamines like Benadryl and night-time somnolence like Nytol and Tylenol PM.
Forbes magazine reported Jan. 29 that the longevity study, which followed nearly 3,500 participants 65 years of age and older over seven years, found that, even though all participants began the study without presenting for dementia, by study’s end nearly 800 participants had developed the mentally debilitating disorder (including some 637 individuals who developed Alzheimer’s). After controlling for a number of variables, researchers found that regular daily doses of four drugs taken over an extended period of time seemed linked to a higher risk of the development of dementia.
The four drugs — Diphenhydramine (found in Benadryl and Nytol), Chlorpheniramine (most common brand: Chlor-Timetron), Oxybutynin (used in over-active bladder medicines; most common brand: Ditropan), and Doxepin (used in anti-depressants; most common brand: Sinequan) — are all anticholinergics. This means that they effectively block acetylcholine, a neurotransmitter, and have side effects like drowsiness, memory loss, and blurred vision.
The recent study adds to a growing compilation of research that links anticholinergics to dementia. Alzheimer’s sufferers often have low brain levels of acetylcholine.
“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,” Shelly Gray of the University of Washington, lead author on the study, notes. “And they should tell their health care providers about all their over-the-counter use.”
The longevity study found that people taking at least 10mg per day of doxepin, 4mg per day of diphenhydramine, or 5mg per day of oxybutynin for over three years were at the highest increased risk of developing dementia. However, the study did not take into consideration short-term effects, such as if there was an increased risk of dementia if short-term users took high doses of the drugs.
AARP.org reported that Gray recommended a “think twice” attitude about sleeping medications (trouble sleeping and insomnia are common among older adults), suggesting that the elderly instead first try non-drug therapies — like avoiding sleep at least six hours before going to bed and maintaining the same wake-up schedule every day, including weekends. Gray also suggested alternative medicines not in the anticholinergics group for other treatments, such as Claritin for antihistamine users and Prozac for those suffering depression.
The dementia study was published in the JAMA Internal Medicine. The team consisted of researchers from the University of Washington, the University of Pittsburgh, the University of Pennsylvania, and other institutes.