Scientists have found a link between large usage of anticholinergic drugs which includes the most popular non-prescription sleep aids and antihistamines (such as Benadryl) and the higher chances of developing Alzheimers and dementia in older people.
Anticholinergics are a known drug to block the neurotransmitter acetylcholine in the body and the brain.
The side effects of this are constipation, drowsiness, and dry eyes and dry mouth.
The research done at the University of Washington School of Pharmacy (Seattle), reported their study in JD.
A leading researcher said:
“Older adults should be aware that many medications – including some available without a prescription, such as over-the-counter sleep aids – have strong anticholinergic effects.”
You Should Not Stop Drug Therapy but Talk To Your Doctor
Doctors should always review their older patients’ drug therapy, which should include over-the-counter drugs – to keep an eye out to reduce fewer anticholinergic drugs or to lower doses.
If anticholinergics are required for the patients because it is the best treatment, then doctors should always look for the lowest effective dose, to regularly monitor the patient to verify the drug is working, and to stop usage if it’s ineffective.
This study used rigorous, which included follow ups for seven years to prove the hypothesis, despite a proven link between dementia and anticholinergics has been found before. By using records obtained from pharmacies, the researchers were able to include non-prescription drug use in their research.
This is also the first study to show a response per dose. Which mean, the higher of the amount of the drug taken to the risk factor for developing dementia.
Another first development that came from the study is it shows that dementia linked to anticholinergics may continue even after people stop taking the drug.
There is a Much Higher Risk for Dementia if Anticholinergics are Taken for More Than Three Years
The researches followed 3,500 men and women who were aged 65 and older with no dementia symptoms.
The researchers used pharmacy computer records to see how much exposure the participants to the study had to anticholinergic drugs.
From the pharmacy records the researchers were able to formulate the daily doses and worked out the anticholinergic exposure for each participant over a 10 year span. The data was updated as the researchers did their seven year follow ups.
Of the 3,500 participants over the length of the study, close to 800 of them developed dementia.
The most used drugs were tricyclic antidepressants, first-generation antihistamines, and antimuscarinics.
The study showed that participants who took at least 10 mg per day of doxepin, 4 mg per day of chlorpheniramine, or 5 mg per day of oxybutynin for more than three years were at the highest risk for dementia.
The risk attributed to Benadryl is the equivalent of 50 mg per day for more than three years or 25 mg per day for more than six years.
A lead researcher in the study stated there are alternative non-anticholnergic drug for doxepin and chlorpheniramine. If a patient want to treat depression they can look to serotonin re-uptake inhibitors (SSRI) such as Celexa or Prozac. There are also 2nd Generation antihistamines such as Claritin for allergies.
Currently, there are not many alternatives to oxybutynin for bladder control, the best method would be behavioral changes.
Many of the participants to the study have agreed to have their brains autopsied after they pass away. This could reveal if anticholinergic usage results in brain changes that results in Alzheimer symptoms.