Exposures to various types of anticholinergic medications were associated with a significantly increased risk of dementia in people aged 55 years or older in a large pharmacoepidemiologic study.
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“This study was designed to assess the association between cumulative anticholinergic drug use and risk of dementia in a large, representative British population,” wrote Carol A. C. Coupland, PhD, of the division of primary care at the University of Nottingham (England), and colleagues. The findings were published in JAMA Internal Medicine.
The researchers conducted a large nested case-control study that included 58,769 patients with dementia and 225,574 matched controls from the QResearch database in England. Each study participant was matched to five controls based on various characteristics, including sex, age, and calendar time, among others.
Prescription data related to 56 different drugs with strong anticholinergic properties, including antipsychotics, bladder antimuscarinics, antiepileptics, antiparkinson agents, and antidepressants were used to measure drug exposure. The study data were analyzed from 2016 to 2018.
“The primary exposure was the total standardized daily doses (TSDDs) of anticholinergic drugs prescribed in the 1 to 11 years prior to the date of diagnosis of dementia or equivalent date in matched controls,” Dr. Coupland and colleagues wrote.
After analysis, the researchers found that exposure to antipsychotics (adjusted odds ratio, 1.70), bladder antimuscarinics (aOR, 1.65), antiepileptics (aOR, 1.39), antiparkinson agents (aOR, 1.52), and anticholinergic antidepressants (aOR, 1.29) was associated with an increased risk of dementia after adjustment for confounding factors.
“Associations were stronger in [dementia] cases diagnosed before the age of 80 years,” the researchers noted.
However, antihistamine, antivertigo/antiemetic, skeletal muscle relaxant, gastrointestinal antispasmodic, antiarrhythmic, and antimuscarinic bronchodilator anticholinergic agents were not associated with any increased risk of dementia.
One key limitation of the study was the absence of medication compliance assessment, which could result in exposure misclassification. Dr. Coupland and colleagues acknowledged this could underestimate some associations with medication exposure.
The stronger risk of dementia found among people who had dementia before age 80 “indicates that anticholinergic drugs should be prescribed with caution in middle-aged and older people,” they concluded.
One question that remains from the current study is whether anticholinergic drugs are a definite modifiable risk factor for Alzheimer’s disease and related dementias, Noll L. Campbell, PharmD, of Purdue University, West Lafayette, Ind., and colleagues wrote in an editorial accompanying the study by Dr. Coupland and associates (JAMA Intern Med. 2019 Jun 24. doi: 10.1001/jamainternmed.2019.0676).
While a pharmacologic basis for this association has been proposed, causation has yet to be established by means of prospective randomized studies. The current supposition is that deprescribing anticholinergic medications has the potential to positively effect cholinergic neurotransmission in certain regions of the brain, which could lead to improved cognitive functioning, and lower the likelihood of developing Alzheimer’s disease and related dementias, they wrote in the editorial.
However, the discontinuation of some anticholinergic agents may pose other risks, such as worsening pain or depressive symptoms, in addition to increasing the utilization of acute care facilities. As a result, high-quality, well-designed, randomized trials are needed to better understand the long-term effects of deprescribing anticholinergic medications. These trials would help inform clinicians, patients, and policymakers about the risks and benefits of deprescribing interventions, Dr. Campbell and coauthors said.
The study was supported by the National Institute for Health Research and the University of Nottingham. The authors reported financial affiliations with ClinRisk Ltd. The authors of the editorial reported receiving support from the National Institute on Aging and the Agency for Healthcare Research and Quality. Dr. Campbell reported receiving personal fees from Astellas Pharma US.
SOURCE: Coupland C et al. JAMA Intern Med. 2019 Jun 24. doi: 10.1001/jamainternmed.2019.0677