Can Pharmaceutical Drugs Increase Your Risk of Dementia or Alzheimers?

Researchers have discovered a significant link between high use of anticholinergic drugs and Dementia/Alzheimers. These drugs block the neurotransmitters in your body located in your central and peripheral nervous system.  Nerve impulses block the binding of a neurotransmitter called “acetycholine” to its receptor nerve cell.  Some of the nerve cells involved are connected to the Parasympathetic system.  This system is responsible for movements in your smooth muscles that you are not even aware of.  Smooth muscles are present in the Gastrointestinal tract, urinary tract, lungs, uterus, arteries, veins etc.   Many medications including over the counter drugs have strong anticholinergic effects.  Again, Anticholinergics are drugs that block the action of the neurotransmitter acetylcholine in the brain and body. Non-prescription sleep aids and the antihistamine Benadryl (diphenhydramine) -have shown an increased risk of developing dementia and Alzheimer’s disease in older people.

Anticholinergics can lead to many side effects, including drowsiness, constipation, retaining urine and dry mouth and eyes.

The researchers, led by Shelly Gray, a professor in the University of Washington School of Pharmacy in Seattle, reported their findings in JAMA Internal Medicine in January 2015.

Professor Gray suggests that health care providers regularly review their patients’ drug prescriptions and over the counter medications to decrease anticholinergic medications when necessary.

If providers need to prescribe anticholinergics to their patients because they offer the best treatment, then “they should use the lowest effective dose, monitor the therapy regularly to ensure it’s working, and stop the therapy if it’s ineffective,” she adds.

There is another study, that also shows that dementia risk linked to anticholinergics may persist long after people stop taking the drugs.  For instance, taking anticholinergics for more than 3 years linked to higher dementia risk.

For their study, Prof. Gray and colleagues tracked nearly 3,500 men and women aged 65 and over with no dementia symptoms at the start of the study. The participants were part of the Adult Changes in Thought (ACT) study in Group Health, an integrated health care delivery system in Seattle. Their researchers used computer records from the pharmacies that dispensed drugs to the participants.

From the pharmacy data they added up all the standard daily doses and worked out the cumulative anticholinergic exposure for each participant over the past 10 years. This was updated as participants were followed up for an average of 7 years.

Over the period of the study, nearly 800 participants developed dementia.

The results showed that the most commonly used medications were antidepressants like Doxepin or Sinequan, first-generation antihistamines (chlorpheniramine, Chlor-Trimeton), and antimuscarinics for bladder control (oxybutynin, Ditropan).

The researchers estimated that people taking at least 10 mg per day of doxepin, 4 mg per day of chlorpheniramine, or 5 mg per day of oxybutynin for more than 3 years would be at greater risk for developing dementia.

Gray also told Medical News about the dose risks associated with Benadryl: “The dose of diphenhydramine that would correspond to the highest risk group is taking the equivalent of 50 mg each day for longer than 3 years – or 25 mg per day for longer than 6 years in duration.” That is pretty scary considering the amount of patients that use Benadryl frequently.

Prof. Gray says there are alternative non-anticholinergic drugs for doxepin and chlorpheniramine. For example, to treat depression there are the selective serotonin re-uptake inhibitor (SSRI) like citalopram (Celexa) or fluoxetine (Prozac). And there are second generation antihistamines like loratadine (Claritin) for allergies.

References: Medical News Today: Catharine Paddock PhD