Long-Term Benadryl Doubles Risk of Memory Loss

Avoid taking anticholinergic drugs like Benadryl, Elavil, Tylenol PM, Excedrin PM, Nytol, Sominex, Demerol, Dramamine, or Unisom in high doses or for long periods of time.

Chronic use of over-the-counter and prescription anticholinergic medicines may increase the risk of mild cognitive impairment (MCI), and even dementia, especially in older individuals.

Several research studies suggest a risk of cognitive problems from over-use these drugs. In one study, as little as 60 days continuous use resulted in memory loss and problems with organizational ability.

In an innocent attempt to combat chronic allergies, you could be worsening your memory and not realize it! This really caught my attention.

Anticholinergic drugs can cause memory loss

I have allergies, so I take Benadryl (Diphenhydramine), Chlor-Trimeton, and other anticholinergic over-the-counter allergy medicines occasionally. However, allergy meds aren't the only anticholinergics that can cause memory loss, according to these studies.

Anticholinergics also include drugs used to promote restful sleep such as Tylenol PM, antidepressants such as Paxil and Elavilm, and medicines used to treat bladder disorders and cardiovascular disease (see the list below for more).

Malaz Boustani, M.D., co-author of a study on anticholinergics published in the journal Alzheimer's and Dementia, describes the risks of these drugs in no uncertain terms:

Simply put, we have confirmed that anticholinergics, something as seemingly benign as a medication for inability to get a good night's sleep or for motion sickness, can cause or worsen cognitive impairment, specifically long-term mild cognitive impairment which involves gradual memory loss.

As a geriatrician I tell my Wishard Healthy Aging Brain Center patients not to take these drugs and I encourage all older adults to talk with their physicians about each and every one of the medications they take. These are very, very common drugs. That's the scary piece.

Older individuals, who often take multiple medications over long periods of time, are especially at risk of developing a high anticholinergic cognitive burden (ACB).

Estimate Your Level of Risk

A person's ACB burden can be calculated using the Anticholinergic Burden (ACB) Scale chart. Using this chart, you can estimate your own ACB score and risk, unofficially.

As recommended in the New York Times article, Cocktail of Popular Drugs May Cloud Brain, use this scale and do some research first before going to your physician:

Use the Anticholinergic Burden scale, developed by scientists from the Regenstrief Institute, to assess your risk. The scale ranks drugs based on the strength of their anticholinergic activity, from zero if there is no effect to 3 for severe effect.

Check with your doctor to follow up, but the basic idea is to add up the risk levels of each anticholinergic drug you take regularly. The risk levels for each drug are on the chart. Risks are cumulative, so the sum total of risk is your total ACB Burden.

If you only know the brand names of the drugs you are taking, first find out their chemical names. Go to a site such as RxList.com and look up the generic chemical name. For instance, Benadry's chemical name is diphenhydramine. The name diphenhydramine is what you'll find listed on the ACB chart.

EXAMPLE: A person takes three anticholinergic drugs regularly, Benadyl (Diphenhydramine), Valium (Diazepam), and Tegretol (Carbamazepine). From the chart, Benadryl alone is a 3 (Severe) on the scale. Valium (Diazepam) is a 1 (Mild) on the scale. Tegretol (Carbamazepine) is a 2 (Moderate) on the scale.

To estimate their anticholinergic burden, they would add up the risk levels for the three drugs, 3 + 1 + 2 = 6. This person therefore has an estimated anticholinergic burden of 6. According to the ACB chart, a total ACB score of three or more is considered clinically relevant.

This person might want to have a conversation with their physician about the advisability of lowering their doses and/or dosage frequency or even dropping some of these meds completely.

Heavy Use of Anticholinergics Impairs Brain Function

During a study on the effects of anticholinergic drugs on the brain published in the Journal of the American Geriatric Society, researchers found that

Chlorpheniramine, an OTC anticholinergic

...those taking more than one anticholinergic drug scored lower on tests of cognitive function than those who were not using any such drugs...

Dr. Noll Campbell, a co-author on the Alzheimer's and Dementia study, summarizes the situation this way:

Millions of older adults are taking sleeping pills or prescription drugs year after year that may be impacting their organizational abilities and memory.

Anticholinergic drugs suppress the activity of acetylcholine, a natural chemical neurotransmitter in the brain used to send messages between brain cells (neurons). Acetylcholine, because it helps neurons communicate, is a critical part of learning and memory.

When the action of acetylcholine is hindered, messages between brain cells are weakened or interrupted, impairing thinking and memory.

List of Moderate-to-High Anticholinegic Drugs

Some drugs can elevate your anticholinergic cognitive load more than others. Medicines in this group are considered to have moderate-to-high anticholinergic effects.

Various anticholinergic over-the-counter and prescription medications can contribute to high ACB load. Taking these drugs may significantly increase your odds of mild cognitive impairment if taken over long periods.

Following is a list of common drugs in the moderate-to-high ACB category:

Anti-Arrythmics - Norpace, Pronestyl, Quinaglute
Anti-Emetics - Dramamine, Antivert, Tigan
Antihistamines - Chlor-Trimeton, Tavist, Tylenol PM, Benadryl
Anti-Parkinsons - Cogentin, Akineton
Anti-Psychotics - Thorazine, Zyprexa, Seroquel
Anti-Spasmotics - Sal-Tropine, Anaspaz, Scopolamine
Skeletal Muscle Relaxants - Soma, Robaxin
Tricyclic Anti-Depressants - Elavil, Norpramin

According to Dr. Campbell,

We found that a high anticholinergic burden -- either from one or multiple drugs -- plus two to three months of continuous exposure to that high burden approximately doubled the risk of developing cognitive impairment.

The elderly, in particular, are commonly prescribed drugs with anticholinergic effects. This can sometimes lead to a misdiagnosis of mild cognitive impairment, when in fact anticholinergic medication side effects may be contributing to memory loss and impaired cognitive function.

Do you (or a loved one) take any of these anticholinergic medications, especially in high doses or continuously for months or years? It might be wise to consult your doctor about whether cognitive side effects should be a concern in your situation.

It may especially be an issue if you are already experiencing problems with memory or other aspects of cognitive function.

One approach is to ask your doctor to calculate the total anticholinergic cognitive burden of the medicines you are taking, or try to estimate it yourself as explained above. If your ACB burden is relatively high, your physician might be able to make adjustments to use the absolute lowest effective dose or exchange certain drug combinations with others having fewer side effects.

Experiencing some memory loss as we get older is normal. But it makes no sense to artificially trigger mental deterioration by over-using medications known to have side effects linked to memory loss and dementia.

Note: It's wise to educate yourself about over-the-counter and prescription drugs you're taking, but always consult your doctor before making any changes to your medications.