For nearly 80 years, consumers have reached for that trusted pink carton or bottle of Benadryl (diphenhydramine) to alleviate symptoms of allergies and allergic reactions. However, in recent years, concerns have been raised about the potential link between the long-term use of anticholinergic medications like Benadryl and the development of dementia in older adults. This debate has sparked interest and prompted many to question the safety of using such medications, especially for prolonged periods.
Navigating through the plethora of information available can be challenging, and it's crucial to distinguish between scientifically validated findings and anecdotal claims.
How Benadryl Works
Before delving into the discussion, it's essential to understand what Benadryl is and how it works. Benadryl is a widely used over-the-counter antihistamine medication primarily used to relieve symptoms of allergies, hay fever, and the common cold. Its active ingredient, diphenhydramine, blocks the action of histamine, a compound released by the body during an allergic reaction, thereby alleviating symptoms such as sneezing, itching, and runny nose.
However, Benadryl also possesses anticholinergic properties, meaning it blocks the neurotransmitter acetylcholine in the brain and peripheral nervous system. Acetylcholine is important for thinking, learning and memory. When Benadryl blocks it, it can cause side effects like feeling sleepy, confused, or dry mouth. That’s why you’ll typically see a disclaimer not to operate machinery or drive a car until you know how the medication will affect you.
The Benadryl-Dementia Debate
The concern surrounding Benadryl and other anticholinergic medications stems from studies suggesting a potential association between long-term use of these drugs and an increased risk of dementia in older adults. One leading theory is that suppressing acetylcholine long-term may lead to Alzheimer’s disease since patients with Alzheimer’s disease have lower levels of acetylcholine. This has such a large influence on the way that Alzheimer’s disease progresses that medications to prevent the brain from breaking down acetylcholine are prescribed to ease Alzheimer’s symptoms.
Some observational studies have reported a higher prevalence of dementia among individuals who regularly use anticholinergic drugs, including Benadryl, compared to non-users. However, it's important to note that these studies primarily establish associations and do not prove causation.
One notable study published in JAMA Internal Medicine in 2015 found a link between the cumulative use of anticholinergic drugs over time and an increased risk of dementia, including Alzheimer's disease. The study followed nearly 3,500 participants aged 65 and older for over 10 years. At the start of the study, participants did not have a diagnosis of dementia.
The researchers documented the medications taken by the participants, which included both prescribed anticholinergic drugs and over-the-counter medications such as Benadryl. Cognitive assessments were conducted for each participant upon enrollment in the study and every two years after that.
By the end of the study, 797 participants had developed dementia. Of those, 637 were judged to possibly or probably have Alzheimer's.
When looking at the data, researchers found a significant correlation between patients who were prescribed anticholinergic drugs and those who developed dementia. They also noted that a higher cumulative intake of anticholinergic medications over the ten-year period corresponded to an increased risk of dementia.
Patients who had the highest exposure levels, equivalent to taking a regular dose for three years, were significantly more likely to have dementia and Alzheimer's disease than those who did not take anticholinergic drugs.
Even among patients with lower exposure levels, there remained an elevated risk of dementia and Alzheimer's, although not as pronounced as in the group with the highest level of exposure.
However, it's essential to interpret these findings with caution. While observational studies provide valuable insights, they cannot establish causation, and other factors may contribute to the observed association. For instance, individuals with certain health conditions requiring long-term medication use may already be at a higher risk of developing dementia.
The study also found that the type of anticholinergic medication did not make a difference, recent depressive episodes did not increase dementia risk, and the timing of the use of anticholinergic use did not make a difference.
Other anticholinergic drugs include:
- First-generation antihistamines like doxylamine, and chlorpheniramine
- Tricyclic antidepressants like amitriptyline, desipramine, and doxepin
- Gastrointestinal antispasmodics like dicyclomine
- Bladder anticholinergics like oxybutynin and tolterodine
- Muscle relaxants like orphenadrine
- Medications for Parkinson's disease like trihexyphenidyl
- Certain antipsychotics like quetiapine
Making Informed Decisions
Given the ongoing discussion about Benadryl and its potential link to dementia, it's important for everyone, especially older adults, to carefully discuss their medication choices with their health care providers. Here are a few things to keep in mind:
Risk-Benefit Assessment: Evaluate the potential benefits of using Benadryl or other anticholinergic medications against the perceived risks, taking into account factors such as symptom severity, alternative treatment options, and individual health status.
Alternative Therapies: Look into different ways to treat allergies that don't involve using pills or drugs that might affect your thinking. There are other options, like using natural methods or trying different medicines that might not cause those kinds of side effects.
Regular Medication Reviews: Make sure to talk regularly with your primary care doctor about the medicines you're taking, especially if you're older and taking a lot of medications. Your doctor can help you figure out if you really need all of them and if they're still right for you. This helps avoid problems that can come from taking too many medicines at once.
Although it's important for each health care provider you visit to check the medications you're already taking and ensure that any new prescriptions won't cause problems, sometimes mistakes can happen. This might occur if you forget to mention a medication you're currently taking, or if your doctor doesn't have access to your complete medical history.
Lifestyle Modifications: Adopt lifestyle habits that promote brain health, such as regular physical exercise, healthy diet, adequate sleep, cognitive stimulation, and social engagement, which may help mitigate the risk of cognitive decline associated with aging.
The Takeaway
While the debate regarding the potential link between Benadryl use and dementia continues, it's important to look at the evidence carefully. Some studies suggest a link between long-term use of certain medications and a higher risk of dementia, but more research is necessary to confirm this. In the meantime, you should talk openly you’re your doctors about the pros and cons of taking certain medications to make informed decisions tailored to your unique needs and circumstances.