Side Effects of Some Antidepressants, Parkinson’s Disease Drugs, May Increase Dementia Risk: Study

New research suggests that the use of certain antidepressants, urological and Parkinson’s disease drugs may increase the risk of dementia. 

In findings published last month in the medical journal The BMJ, U.K. researchers warn that side effects of some anticholinergic drugs may cause dementia or cognitive decline among older individuals living in nursing homes or the community.

Anticholinergic drugs block certain neurotransmitters, and are used in a wide variety of medications, including antipsychotics, motion-sickness drugs, drugs for depression, Parkinson’s disease, and gastrointestinal disorders, among others. The power of the doses and the drugs are defined by the Anticholinergic Cognitive Burden (ACB) scale.

Researchers noted that as middle-aged and older adults increasingly take multiple drugs, it is important that the potential adverse effects of these drugs are better understood.

Anticholinergic drugs are already considered inappropriate for individuals with dementia, and long-term exposure has previously been linked to cognitive decline among older individuals.

Some antidepressants with anticholinergic effects include some belonging to the class known as selective serotonin reuptake inhibitors (SSRIs), like Zoloft, Celexa and Cymbalta. Most anticholinergic drugs used to treat Parkinson’s disease are only used when symptoms are mild, are older drugs, and most are sold as generics.

Researchers looked at data on 30,770 patients ages 65 to 99 who were diagnosed with dementia between April 2006 and July 2015 at general practices in the U.K. They were matched up with nearly 300,000 controls without dementia.

According to the findings, there was an 11% increased risk of dementia when patients were prescribed at least one anticholinergic drug with an ACB score of 3 or higher. However, among those drugs, the researchers found that the strongest associations were with antidepressant, urological or antiparkinson drugs. Others, such as ahticholinergic drugs used to treat gastrointestinal problems, were not clearly linked to dementia.

“A robust association between some classes of anticholinergic drugs and future dementia incidence was observed,” the researchers determined. “This could be caused by a class specific effect, or by drugs being used for very early symptoms of dementia. Future research should examine anticholinergic drug classes as opposed to anticholinergic effects intrinsically or summing scales for anticholinergic exposure.”