If you get Parkinson’s disease, there’s a greater than 80% chance you’ll have cognitive impairment within 20 years. So Parkinson’s patients are commonly prescribed drugs to treat cognitive impairment. Alarmingly, a new study finds that these patients also are being prescribed drugs that work against their dementia drugs. Nor is it an occasional mix-up—it’s happening to huge numbers of Parkinson’s patients! Read on to learn how to protect yourself or your loved one.

Treating Parkinson’s cognitive impairment, one of the major reasons for someone with the disease to end up in a nursing home, is critical. The cognitive drug most commonly prescribed is donepezil hydrochloride (Aricept), which belongs to a class of drugs called acetylcholinesterase inhibitors. Other drugs in that class include rivastigmine tartrate (Exelon) and galantamine hydrobromide (Razadyne). These drugs work by increasing levels of acetylcholine, a brain chemical that supports cognition.

However, Parkinson’s primarily affects older adults, an age group that is prone to other medical problems such as depression, bladder incontinence, heart problems and allergies. So it’s very common for Parkinson’s patients to also be prescribed drugs to treat these conditions—and some of the drugs most often prescribed are anticholinergics such as paroxetine (Paxil) and oxybutynin (Ditropan). These drugs can decrease cognition, especially in people who are cognitively vulnerable—for instance, people with Parkinson’s.

Researchers from Perelman School of Medicine at University of Pennsylvania reviewed one year of Medicare prescription records for Parkinson’s patients and identified 65,000 who had been prescribed at least one acetylcholinesterase inhibitor. They found that about 45% of these patients had also been prescribed an anticholinergic drug for some other health condition.

The researchers further found that the risk for being prescribed these pharmacologically opposing drugs varied by region of the country and by race or ethnicity of the patient. Highest risks were in southern and midwestern states and among Hispanic patients.

Taking an anticholinergic along with an acetylcholinesterase inhibitor is like drinking an energy drink with a sleeping pill. It’s a “prescription” that the researchers say should never happen. They also point out that many anticholinergic medications are available over the counter, and the study did not include these—for example, allergy, cold, flu, motion sickness and sleep-aid drugs can contain diphenhydramine (Benadryl), which is an anticholinergic. So the likelihood that Parkinson’s patients are taking pharmacologically opposing drugs may be even greater.

Pharmacologically opposing drugs are bad enough for the Parkinson’s patients themselves. Even worse: Such widespread co-prescribing of drugs that work against each other may also be interfering with Parkinson’s research. Most studies assume that cognitive decline is due to death of brain cells or buildup of certain proteins in the brain—when at least some symptoms of cognitive decline among these patients may be side effects from anticholinergic drugs.

If you or a loved one is being treated for Parkinson’s, discuss with your doctor and/or pharmacistallmedications—prescription and OTC—that are being taken. If it turns out that you’re taking both an acetylcholinesterase inhibitor and an anticholinergic, discuss with your doctor whether another medication combination might be better for you.

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