olanzapine (Parkinson’s disease)

One of the antipsychotic medications taken to treat symptoms of psychosis such as HALLUCINATIONS, CONFUSION, DELUSIONS, PARANOIA, and dementia. About one third of people in the late stages of Parkinson’s disease have symptoms of psychosis. These symptoms can arise as a consequence of Parkinson’s disease, be present because of coexisting Alzheimer’s disease, or develop as undesired side effects of anti-parkinson’s medications, particularly Levodopa and dopamine agonist MEDICATIONS.

Though olanzapine (Zyprexa) is classified as an atypical antipsychotic because it affects the brain’s neurochemical processes in different ways than conventional antipsychotics do, making it less likely to worsen Parkinson’s symptoms than antipsychotic medications are necessary, olanzap-ine still causes extrapyramidal motor side effects in about 30 percent of people with Parkinson’s disease who take it. As do other antipsychotic medications, olanzapine has some action as a dopamine antagonist (it blocks dopamine activity) on selective dopamine receptors, primarily D1, whereas conventional antipsychotic medications act nonselectively. The dopamine receptors primarily involved with motor function are D1, D2, D3, and D4. Quetiapine (Seroquel) and clozapine (clozaril) are better choices for people with Parkinson’s balance between enough focused dopamine antagonist activity to suppress the symptoms of psychosis but not so much that it carries over to motor disturbances.

The first therapeutic approach for psychotic symptoms in a person with Parkinson’s should be to evaluate the medication regimen, as often making adjustments to medications and dosages can reduce or alleviate such symptoms. Antipsychotic medications often exacerbate motor and cognitive impairments in people diagnosed with Parkinson’s disease and should be used only when other therapeutic approaches are ineffective and the psychotic symptoms are severe enough to mandate medical management. Atypical antipsychotic medications are commonly used to treat symptoms of psychosis in people with Alzheimer’s disease, and when such extrapyramidal side effects occur can create a confusing clinical picture as Parkinson’s and Alzheimer’s frequently coexist. It can be difficult to determine whether Parkinson’s-like symptoms are in fact a manifestation of Parkinson’s disease or side effects of the antipsychotic medication. Doctors generally presume the former when symptoms persist after stopping of the antipsy-chotic medication and respond to anti-Parkinson’s medications such as levodopa.

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