There is a lot we still do not understand about brain ailments like depression and dementia, and a worrying new study suggests that common drugs used to treat depression may be connected to an increased risk of dementia. The findings, published recently in the British Medical Journal, found that certain anticholinergic drugs are associated with a 30 percent higher risk for development of dementia.

Scientists examined patients who took the drugs for a year or more to treat depression, Parkinson’s disease, and urinary incontinence. Those who took other types of anticholinergics, such as those used for asthma and gastrointestinal problems, did not experience the same increased risk.

The study examined more than 40,000 patients between 65 and 99 years of age who had been diagnosed with dementia over a period of 10 years. They compared those records to those of more than 283,000 people who did not have dementia to come to their findings.

“Dementia is a leading cause of disability and death,1 and its prevention is a global public health priority,” reqads the intro to the paper. “Dementia is caused by a number of different neurodegenerative processes that contribute to irreversible cognitive decline and associated symptoms, such as the progressive loss of independence and daily functioning. Mixed dementias are more prevalent than is often recognised, with symptoms often more closely linked to overall pathological burden as opposed to any specific disease process.”