Study Links Antidepressants, Bipolar Medications, Parkinson's Drugs To Dementia

SAN FRANCISCO (KPIX 5) -- New research is raising important questions as to whether certain widely-prescribed drugs -- antidepressants, bipolar medications, and Parkinson's drugs -- may be linked to dementia.

Globally, 50 million people are living with dementia. It is predicted that will increase to 132 million by 2050.

Doctors and public health experts realize that countries need to develop preventive health policies to reduce the neurodegenerative condition.

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One strategy: to swap out certain medications or have doctors think twice before prescribing them. These medicines include certain antidepressants, bipolar medications, antispasmodics taken for bladder control, as well as some Parkinson's drugs.

The drugs in question are called known as anticholinergics. They block a specific neurotransmitter called acetylcholine in the central and peripheral nervous systems.

"We analyzed people who developed dementia and people who didn't develop dementia," explained Professor Chris Cox, a researcher at the University of East Anglia in the United Kingdom and one of the authors of the new report.

The study is the largest, most detailed one of its kind. Researchers poured over 300,000 medical records with millions of prescriptions, and then performed a sophisticated statistical analysis.

"So our studies for the first time had indicated a strong association between taking certain anticholinergic drugs and the risk of getting dementia," said Fox.

The British team found the long-term use of these drugs is linked to dementia, even when the medications are taken up to 20 years before a diagnosis.

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The drugs include antidepressants such as Paxil and Elavil, and medications used for bipolar disorder including Zyprexa and Seroquel.

The research also found an associated risk with medications used for bladder conditions, as well as Parkinson's disease.

"It's important but it's not conclusive," commented Dr. Barbara Sommer, a geriatric psychiatrist at Stanford Medical Center and an expert in anticholinergic medication. She cautioned that the study does not prove these drugs cause dementia. Even so, she said if you take medication, over-the-counter drugs, even supplements, you should reassess if you really need them.

"You have to measure the risk and the benefit of any medication that you take." said Sommer.

She recommends patients review all prescription drugs, over-the-counter medicines, and supplements with a specialist. "Take them to your doctors and go over each mediation one by one asking how anticholinergic it is, if at all," said Sommer.

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While this new research found no risk with popular over-the-counter antihistamines and sleep aids, Sommer said she doesn't think they're off the hook. Previous research shows compelling evidence the long-term use of these drugs may be problematic.

Diphenhydramine is the active ingredient found in Benadryl and other over-the-counter sleep aids. Sommer explained how drugs that contain diphenhydramine get into the brain and sit there for a little while. Some of the newer antihistamines have anticholinergic properties but to a much lower degree  For example, Claritin or Zyrtec may be a better choice than antihistamines that contain diphenhydramine.

"I just think it would be better to use another medication if possible," she advised, adding that there are other, safer strategies you can follow if you're having trouble sleeping.

As to whether anticholinergics cause permanent harm to the brain, Sommer said it's hard to know but she believes there may be a very small population of people whose dementia is hastened by these drugs.

Patients should not to stop any medication without first talking to their doctor. "Some may have withdrawal symptoms or other adverse effects," cautioned Fox.

For some individuals, anticholinergic drugs may be saving their lives, and the benefit may far outweigh any risk.

To reduce the chances of dementia in the meantime, researchers advise to exercise, keep a healthy weight, don't smoke or drink too much alcohol, control your blood pressure, and keep a good social network.

For a list of anticholinergic drugs and how they rate: CLICK HERE