Benadryl = Dementia?

As many of us know, Penn State is infected with sick college students. I find it nearly impossible to go ten seconds without someone either sneezing or coughing profusely around me in our SC 200 class. When we are sick, many of us take medication like Benadryl to control or cough or runny nose. We are also well aware that there are numerous side-affects listed on the packaging but we barely bother to read around 30 side-affects. Could dementia be one of those side affects?

Background Information

Dementia is a very serious condition that affects millions of people around the world. If you are not aware of dementia, it is something caused by our brains which causes things like memory loss, impaired thinking, confusion, and mental decline. Dementia is most common in elderly people over age 60.


Benadryl is a very common over-the-counter drug that is widely available at places like Walgreens and CVS all across the world. Benadryl is part of a class of drugs called antihistamines. Antihistamines work by blocking histamine receptors in our body which can cause things like runny nose and insomnia.


In this case, the null hypothesis would be that antihistamines like Benadryl do nothing to cause dementia. While, the alternative hypothesis would be that in fact antihistamines play a role in dementia. Scientists can choose to either accept or reject the null hypothesis.



A study conducted by JAMA Internal Medicine in 2015 studied the potential link between anticholinergic use and dementia. Anticholinergics are drugs that block acetylcholine from reaching the body (antihistamines like Benadryl are anticholinergic drugs). The study was a longitudinal study, which as we mentioned in class in the “is smoking bad for you” session, is a observational study that studies some sort of trend across a long period of time. The longitudinal study tracked 3,434 people aged 65 and older over 10 years. Specifically, the study looked into constant use of anticholinergics and dementia. New participants were enrolled into study to replace previous participants that passed away. Computerized pharmacy dispensing data was used to see if the participants were using anticholinergics frequently. This data showed the name of the person, the amount, and how they took the prescribed anticholinergics.



The results of the study showed a positive correlation between anticholinergic use and dementia in the participants. 797 out of the 3,434 participants developed during the course of the study. Participants who took more anticholinergics had a higher risk of developing dementia. A number of third variables like college education, regular physical activity, and smoking were taken into account.




In my opinion, this is one of the most important studies ever conducted in medicine. I believe that the study was extremely well conducted by accounting for a number of third variables and had an incredibly large sample size. Most of my previous blogs contained studies that had 20-50 people, this one had just under 3,500. Although this study definitely proves the positive correlation between anticholinergic use and dementia, we know that correlation need not equal causation. This study does not prove that if you take anticholinergics you will get dementia, it just shows that there is a link between the two. Reverse causation can be ruled out due to the lapse of time.


Works Cited

MS, Shelly L. Gray PharmD. “Strong Anticholinergics and Incident Dementia.”The JAMA Network. Jama Internal Medicine, 01 Mar. 2015. Web. 20 Oct. 2016.



3 thoughts on “Benadryl = Dementia?

  1. Rebecca Jordan Polaha

    This definitely caught my eye because I am constantly battling with allergies. I also take Benadryl whenever i’m on an airplane (I know, that’s not good) so I do take it often. Now I know that I should not abuse Benadryl because It might catch up to me in the future in a negative way. I’m actually finding it hard to believe that an over the counter drug can cause such a deteriorating disease to an individual. I have a link here that shows how to safely use Benadryl :

  2. Delaney Ann Flynn

    Personally, I take Benadryl extremely often. Whenever I suffer from allergy attacks or have a runny nose, I reach for the bottle. Even worse, I’ve caught myself taking it to help me fall asleep because the medication makes you extremely drowsy. This post opened my eyes about the importance of taking medication correctly. The results of the studies you included definitely show a strong correlation between antihistamines and dementia. Web MD has an article that discusses your topic further and ties anti depression medications to possible dementia later in life as well.

    Web MD

  3. Sean Kyle Reilly

    Hey Brendan!

    Although it is currently flu season, and soon enough Spring will be around the corner to spring up the number of students using Benadryl and other medications like it, there is one thing to keep in mind when making this link to dementia and that is the naive nature typically associated with younger people – even college students. We tend to think that we will live forever and that we are impervious to the diseases and ailments plaguing millions of older, and even younger, citizens around the world today. So, while there may be a link to dementia, even if does not correlate 100% with the use of benedryl and other anticholinergics, the short term benefits of relieving my symptoms through using these products far exceed any type of consequence I may face decades from now. The University College London did an excellent study on this, and I think it is worth the read (!

    Either way, great job with your post! I found it to be very informative and worth reading. Best of luck with the rest of the class!

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