A new study suggests anticholinergic medications may increase the risk of accelerated cognitive decline, especially in older adults at high risk of developing Alzheimer’s disease.

Anticholinergic drugs block the action of acetylcholine, a chemical messenger that controls a range of automatic bodily functions and plays a vital role in memory and attention.

Doctors prescribe these drugs for a variety of conditions, including urinary incontinence, overactive bladder, chronic obstructive pulmonary disorder (COPD), seasonal allergies, and depression.

However, over the past decade, growing evidence indicates anticholinergics may increase the risk of dementia in older adults.

Researchers at the University of California, San Diego, have now established a link between anticholinergics and mild cognitive impairment, which can lead to dementia, including Alzheimer’s disease.

The increased risk was particularly pronounced in individuals who had biomarkers for Alzheimer’s in their cerebrospinal fluid and in those with an increased genetic risk of developing the illness.

“We believe this interaction between anticholinergic drugs and Alzheimer’s risk biomarkers acts in a ‘double hit’ manner,” says Alexandra Weigand, who led the study.

In the first hit, she explains, Alzheimer’s biomarkers indicate that degeneration begins in a small region of the brain called the basal forebrain, which produces acetylcholine.

“In the second hit, anticholinergic drugs further deplete the brain’s store of acetylcholine,” she says. “This combined effect most significantly impacts a person’s thinking and memory.”

In their paper, the authors conclude:

“Our findings suggest that the reduction of [anticholinergics] prior to the onset of overt cognitive problems may represent a critical period for intervention before these medications lead to lasting alterations in important cholinergic networks.”

They note that a limitation of their study was the homogeneity of the sample population in terms of education, ethnicity, and race. As a result, their findings may not generalize to the wider population.

In addition, participants were relatively healthy at the start of the study compared with the broader population.

For example, whereas one-third of their subjects were taking anticholinergics, other studies suggest that up to 70% of older adults take these drugs. This limited the new study’s ability to investigate the effect of the number of anticholinergics taken and their dosages.

Finally, the total number of participants in the study was relatively small, which may have limited the precision of its estimates.

Medical reference: Medical News Today