Harvard Women's Health Watch

Common drugs linked to dementia

Medications called anticholinergics are used to treat a host of conditions—overactive bladder, depression, allergies, and Parkinson's disease. They usually aren't recommended for older adults because one of the most common side effects is confusion and difficulty reasoning. Early studies have also indicated that long-term anticholinergic use is associated with an increased risk of dementia, and a recent study by researchers at the University of Washington adds more evidence to support that connection. The results were published online Jan. 26, 2015, by JAMA Internal Medicine.

The researchers tracked almost 3,500 men and women ages 65 and older who were free of dementia. When they matched prescription data for the previous 10 years with the participants' health outcomes, they determined that using anticholinergics was associated with an increased risk of developing dementia. Moreover, dementia risk increased with the dosage of the drugs and the length of time they were used. While people who had taken these drugs daily for the equivalent of three months had no increase in risk, those who had used them for over three years had a 54% greater risk than nonusers.

It's possible that people taking anticholinergics were already on the way to developing dementia, and that the drugs themselves may not have been the cause. However, the risk was just as high for drugs to control bladder and allergy problems as for anti-depressants and sleeping pills, reducing the -likelihood that people might have had early dementia and were using anticholinergics to alleviate their symptoms.

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