Popular sleeping aids may increase risk of dementia

13 Dec Popular sleeping aids may increase risk of dementia

Popular non-prescription and prescription medications, including the active ingredient in Benadryl, have been linked to increased risk of developing dementia by a study published in a top-tier medical journal.

According to researchers publishing in JAMA Internal Medicine, the risk is most associated with long-term use of four common meds:

  • Diphenhydramine – an over-the-counter antihistamine used to treat allergies and aid sleep. Benadryl is the most common brand, but this drug is in several brands of allergy and sleep-inducing meds..
  • Chlorpheniramine – an over-the-counter antihistamine used to treat allergies. Oxybutynin – a prescription medication used to control over-active bladder conditions.
  • Doxepin – an older prescription antidepressant (from a class of meds called tricylic antidepressants).

The study followed 3,434 people over the age of 65 for seven years. None of the participants showed signs of dementia at the start of the study period. During the seven years, almost 800 of the participants developed dementia (637 developed Alzheimer’s disease; the rest were afflicted with other forms of dementia). After controlling for a range of other factors, the researchers were able to link heightened risk of dementia to a daily dose of the four medications.

All of the drugs in question are anticholinergics – meaning they block a neurotransmitter called acetylcholine in the nervous system. Common side effects of taking anticholinergics include drowsiness, blurred vision and memory loss. People suffering from Alzheimer’s disease typically have low brain levels of acetylcholine, and previous research has shown a link between taking anticholinergic drugs and increased risk of dementia in older adults.

Lead study author Shelley Gray, director of the geriatric pharmacy program at the University of Washington School of Pharmacy, commented:

“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. And they should tell their health care providers about all their over-the-counter use.”

While no one should stop taking prescribed medications without consulting their doctor, Gray believes the study results should prompt people to discuss possible alternatives or dose reductions. “Health care 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.”

The study showed that people taking at least 10mg per day of doxepin, 4mg per day of diphenhydramine, or 5mg per day of oxybutynin for more than three years were at the highest increased risk of developing dementia.

It’s important to note that this research does not show a conclusive cause-and-effect relationship between taking these medications and developing Alzheimer’s. This is a cohort study, meaning it observed a large group of people over time searching for patterns in their behaviour that correlate with certain medical outcomes. Even though the researchers controlled for other factors, it is impossible to rule out everything else that could contribute to greater risk of developing a disease. The study also can’t tell us if only long-term daily use of the drugs increases dementia risk, or if several short-term periods of taking a large dose might have the same result. What we can say for sure is that the correlation uncovered in this study, in addition to results from previous research, is significant enough to be of concern, particularly for older adults.

Quoting the researchers: “Given the devastating consequences of dementia, informing older adults about this potentially modifiable risk would allow them to choose alternative products and collaborate with their health care professionals to minimize overall anticholinergic use. Additional studies are needed to confirm these findings and to understand the underlying mechanisms.”
The study was published in JAMA Internal Medicine.