New drug may provide first safe, effective treatment for psychotic symptoms


For many patients suffering from Parkinson’s disease, tremors and loss of movement aren’t the only symptoms they have to cope with.  In more than half of cases, people are also plagued with distressing symptoms of psychosis, which often include visual hallucinations and paranoid thoughts.

While numerous effective treatments exist for the motor problems associated with Parkinson’s, current treatment options for psychotic symptoms are either ineffective or potentially harmful.  And some form of treatment is definitely needed – psychosis is considered to be the main reason why people with the disease are admitted to nursing homes, and also significantly increases a patient’s risk for early death.   

To address this problem, researchers from King’s College London have identified a pre-existing drug that may effectively control the psychotic symptoms stemming from Parkinson’s disease.  Known as pimavanserin, the drug works by blocking serotonin 5-HT2A receptors in the neocortex, which had been previously associated with visual hallucinations.

“In the majority of (Parkinson’s patients), lots of chemical transmitters in the brain are imbalanced,” study author Clive Ballard, professor of age-related diseases at King’s College, told  “But the 5-HT system, that chemical system is quite imbalanced and strongly associated with the presence of these symptoms.  So the drug targets that in the brain.”

Ballard noted that the drugs currently used for Parkinson’s-related psychosis are two dopamine antagonist antipsychotic drugs, which either target the wrong areas of the brain or too many areas all at once, leading to unwanted side effects.

“The only two drugs that are actually tolerated are quetiapine, but it’s not effective, and the other drug is an antipsychotic called clozapine, which is effective but has a lot of side effects. For example, it can suppress the white blood cells,” Ballard said.  “Clozapine is approved as a second line treatment, but there’s no first line treatment.  So the reality is people are either getting no treatment are getting an ineffective treatment.”

While clozapine works by targeting the 5HT receptors, Ballard said it also unnecessarily targets other brain systems.  The researchers chose to analyze the drug pimavanserin, because it only targeted the 5HT system.

For their study, Ballard and his colleagues recruited 199 Parkinson’s patients with psychosis from the United States and Canada who were over the age of 40.  Each participant was randomly assigned 40 milligrams of pimavanserin to take orally each day or a matching placebo to take each day for six weeks.

Using a nine-item Parkinson’s disease-adapted scale (SAPS-PD) to assess the patient’s psychotic symptoms, the researchers found that patients taking the pimavanserin showed a significant improvement in psychotic symptoms compared to the patients taking the placebo (37 percent versus 14 percent).  They also noticed other improvements among the patients taking pimavanserin, including improved sleep and a decrease in burden being placed on their caregivers.  The drug was also very well tolerated, showing little side effects.

Because of their results, the researchers have submitted an application for drug approval to the U.S. Food and Drug Administration, so that physicians can start prescribing pimavanserin for symptoms of psychosis.  They also believe that the drug could be used to treat these same symptoms stemming from other neurodegenerative diseases, such as Alzheimer’s disease.

“Not only does (psychosis) cause stress to the person themselves, but it is strongly associated with people needing to go into a nursing home and whether their carers are capable of handling them or not,” Ballard. “So hopefully this drug is reducing the need of that person going into a care home, and improving the overall quality of the patient and their carer.”



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