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Diseases & Conditions

Mental Disturbances Associated with Parkinson's Disease

What mental disturbances are associated with Parkinson’s?

Certain mental disturbances — such as hallucinations, delusions, and paranoia — are possible complications of Parkinson's disease and/or its treatment.

Hallucinations, delusions, and paranoia are disturbances of perception. Hallucinations are perceptions that occur without connection to an appropriate source. Seeing things that other people do not see is a common type of hallucination. Delusions are false personal beliefs that go against reason or facts. Paranoia is characterized by feelings of being followed or harmed in some way. However, for most patients with Parkinson’s disease, these disturbances can be controlled.

How are these disturbances treated?

The first step is to address any other medical conditions that could produce hallucinations, delusions, or paranoia. These include imbalances in the chemicals of the blood that help control water levels in the body and help with transmitting nerve impulses. Kidney, liver, or lung failure, as well as certain infections, also could cause mental disturbances.

Many times, the medicines used to treat Parkinson's disease can cause these mental disturbances. Certain medicines are more likely to cause these problems than are others. Sometimes hallucinations, delusions, or paranoia can be controlled without making drastic changes to the Parkinson's treatment by switching from one medicine to one less likely to cause the problems. Other medicines that the patient might be using, including over-the-counter medicines, should be reviewed as potential causes of these disturbances.

Some patients might not be able to tolerate changes in their Parkinson's disease medicines without increasing their motor symptoms. In these cases, it might be necessary to treat the patients with anti-psychotic medicines. Older traditional neuroleptics — such as thioridazine (Melleril) and haloperidol (Haldol) — should not be used as they might worsen motor symptoms. Fortunately, there are other alternatives. Medicines such as olanzapiene (Zyprexa), with quetiapine (Seroquel) and clozapine (Clozaril) can effectively control hallucinations at low doses without worsening Parkinson's symptoms. Clozapine is the least likely to worsen Parkinson's symptoms. Unfortunately, there is a 2 percent chance of a drop in the white blood cell count. For that reason, quetiapine is often tried first. Frequent blood testing is required when taking clozapine.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 9/20/2005