The nonstop “24/7” nature of the world can disrupt our normal sleep-wake patterns, prompting many people to turn to over-the-counter sleep aids for a little help falling asleep at night. However, that habit, if made a consistent one, could lead to potentially serious damage when it comes to ones mental health.
A new study looking at anticholinergic drugs — a category that includes common non-prescription sleeping aids and antihistamines like Benadryl — found that the long-term use of such medications in higher doses can lead to an increased risk of developing dementia, including Alzheimer’s disease, in the future. It’s the first study of its kind to demonstrate this dose-response effect, meaning that the higher, cumulative consumption of the drug, the higher the likelihood of a person developing dementia later in life. It’s also the first to suggest that this dementia risk may persist — and be irreversible — even years after people have stopped taking these drugs. The findings were published in JAMA Internal Medicine in late January.
Dr. Shelly Gray, a professor at the University of Washington’s School of Pharmacy and lead author of this study, originally intended to disprove this association that had been researched previously and published last year with her more rigorous study design. Dr. Gray and her colleagues tracked approximately 3,5000 men and women aged 65 and older who exhibited no dementia symptoms at the beginning of the study. Each participant was part of the joint Group Health–University of Washington study funded by the National Institute on Aging, which made it more efficient for them to track exposure to anticholinergic drugs via each person’s pharmacy computer records.
Anticholinergics, which block the neurotransmitter acetylcholine in the brain and body, are typically taken to address gastrointestinal problems, urinary issues, respiratory disorders and insomnia, with side effects ranging from drowsiness to constipation urine retention to dry mouth.
Using more rigorous methods, a follow-up period extending beyond seven years, a more thorough assessment of pharmacy records regarding the medication use (both prescription and over-the-counter options), Dr. Gray’s team was better able to confirm this link between anticholinergic medication use and dementia.
The pharmacy data allowed Dr. Gray and her team to calculate the standard daily medication doses of each study participant as well as their cumulative exposure to anticholinergics over a 10-year period. Over the course of the study, almost 800 participants developed a degree of dementia. The pharmacy data also revealed the most common medications (and daily doses) used by the group of participants: antidepressants (10 mg per day of doxepin), first-generation antihistamines (4mg per day of chlorpheniramine) and antimuscarinics for bladder control (5 mg per day of oxybutynin). They estimated that the use of such amounts for more than three years could result in a greater risk of developing dementia.
According to Dr. Gray, substitutes are available for the first two medications in this list. A selective serotonin re-uptake inhibitor like citalopram or fluoxitene can aide depression symptoms, while a second-generation antihistamine like loratadine can address allergies without the harmful, anticholinergic exposure. However, it can be more difficult to find an effective alternative for for urinary incontinence.
Dr. Gray hopes that this study will help inform older adults that many common medications have strong anticholinergic effects and come with a degree of risk when it comes to their mental health. However, for adults who are already taking drugs found to be problematic in this study, it’s important to talk to your physician before terminating any medicinal regimen, as well as inform them of the over-the-counter drugs you take — no matter how mainstream and benign they may seem.