If you take medication to treat conditions such as urinary incontinence, insomnia, asthma, allergies or depression, you might be at risk for dementia.

Anticholinergic (AC) medication is not limited to over the counter drugs but also in popular prescription medicine such as tricyclic antidepressants like doxepin (Sinequan), anti histamines like chlorpheniramine (Chlor-trimeton) & diphenhydramine (Benadryl) and bladder control drugs like oxybutynin (Ditropan).  

Anticholinergic medication works by blocking a critical brain chemical called acetylcholine, which is crucial for memory. AC medication affects cognitive abilities such as attention and working memory in the short term. However, an earlier study from JAMA Neurology, on the association between AC medication use and cognition reports not only will taking AC drugs for a long period of time increase cognitive impairment and risk for dementia significantly, but the effects of the drugs might persist even when the person stopped using the drug. Click here to see a more comprehensive list of AC medication from Drugs.com.

“Older adults should be aware that many medications including some available without prescription, such as over-the-counter sleep aids, have strong anticholinergic effects” said study author Shelly Gray, director of the geriatric pharmacy program at University of Washington School of Pharmacy. Here’s a of drugs the scientist researched.

The researchers found that overall, long-term use of the drugs significantly increased the risk of developing dementia, including Alzheimer’s disease. The study found, for example, that people taking at least 10 milligrams per day of doxepin (Sinequan, a sleep and depression aid), 4 milligrams a day of diphenhydramine (Benadryl, for allergies or sleep), or 5 milligrams a day of oxybutynin (a bladder control drug) for more than three years would be at increased risk for developing dementia.

A more recent study by JAMA Neurology, also conclude similar results. The 451 participants, average age 73, had no cognitive decline at the start of the trial. They were involved in 2 different studies: a cognitive test and underwent imaging studies to explore brain functions and structures.

Participants who were taking AC medications were more likely to score poorly on test that include problem solving, memory and executive functions. The MRI showed changes in the size and structure of the brain as well as lower metabolic activity of the brain responsible for memory.  

PPI (Proton Pump Inhibitors), which are taken daily by tens of millions of people worldwide are also at risk for dementia. The authors of the study on PPI’s risk for Dementia wrote:

“In this cohort study including more than 70,000 participants and using longitudinal observational data derived from the German statutory health insurer Allgemine Ortskrankenkassen (AOK), elderly patients 75 years of age or older receiving PPI medication had a significantly increase risk of incident dementia compared with patients 75 years of age or older not receiving PPI medication.”

“The avoidance o PPI medication may prevent the development of dementia. This finding is supported by recent pharmacoepidemiology analyses on primary data and is in line with mouse models in which the use of PPIs increased the level of β-amyloid in the brains of mice.”

Many people know that your risk for dementia happens through genetics or head injuries or concussions, but the affect of AC drugs are not known to many. Make sure you understand what you’re putting in your body. Understand what to look out for if you take over-the-counter medications. (If the medication contains PM, it most likely contains diphenhydramine, most commonly known as Benadryl)

Dr. Gray suggest patients should substitute for other drugs that do not have anticholinergic effects, such as a selective serotonin re-uptake inhibitor (SSRI) like citalopram (Celexa) or fluoxitene (Prozac) for depression and a second-generation antihistamine like loratadine (Claritin) for allergies. It’s harder to find alternative medications for urinary incontinence, but some behavioral changes can reduce this problem.  

Patients “should tell their health care providers about all their over-the-counter use,†Dr. Gray said. In addition, “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…If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient,†Dr. Gray said, “they should use the lowest effective dose, monitor the therapy regularly to ensure it’s working, and stop the therapy if it’s ineffective.â€