From University of Washington Health Sciences NewsBeat:
Higher dementia risk linked to more use of common drugs
UW-Group Health study of seniors shows danger of extended use of over-the-counter drugs such as Benadryl
HSNewsBeat | Updated 8:30 AM, 01.26.2015
A large study links a significantly increased risk for developing dementia, including Alzheimer’s disease, to taking commonly used medications with anticholinergic effects at higher doses or for a longer time.
Many older people take these medications, which include nonprescription diphenhydramine (Benadryl). JAMA Internal Medicine published the report.
Anticholinergic effects happen because some medications block the neurotransmitter called acetylcholine in the brain and body, Gray explained. That can cause many side effects, including drowsiness, constipation, retaining urine, and dry mouth and eyes.
It is the first study to associate a greater risk for dementia to a higher use of anticholinergic medications. It is also the first to suggest that dementia risk linked to anticholinergic medications may persist and not be reversible years after people stop taking the drugs.
“If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient, they should use the lowest effective dose, monitor the therapy regularly to ensure it’s working, and stop the therapy if it’s ineffective,” Gray said. “No one should stop taking any therapy without consulting their health care provider. Healthcare 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.”
The most commonly used medications in the study were tricyclic antidepressants like doxepin (Sinequan), first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan).
The study estimated that people taking at least 10 mg/day of doxepin, 4 mg/day of chlorpheniramine, or 5 mg/day of oxybutynin for more than three years would be at greater risk for developing dementia. Gray said substitutes are available for the first two: 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.