Minimizing Doses of Antipsychotic Medication in Older Patients With Schizophrenia.

Summary

Since side effects of antipsychotics, dopamine D2 receptor blockers, frequently occur in older patients with schizophrenia and the risk is dose dependent, clinical guidelines universally advocate the use of lower doses. However, there is no report to test this dosing guideline with measurements of D2 receptor blockade caused by antipsychotics. In this study, dopamine D2 receptor occupancy will be measured, using Positron Emission Tomography (PET), in 40 patients aged 50 and older with schizophrenia-spectrum disorders before and after a gradual 40 % dose reduction of antipsychotics that was safely achieved in the past study while setting a target dose still above the lower limit of the dose range recommended in clinical guidelines for older patients. Our goal is to relate changes in clinical outcome, including subjective and objective clinical ratings, to dopamine D2 receptor occupancy, and compare these results with the data for younger patients in the literature.

Timeline

Start

2009-10

Primary completion

2015-08

Completion

2015-08

Publications

• Iwata Y, Nakajima S, Caravaggio F, Suzuki T, Uchida H, Plitman E, Chung JK, Mar W, Gerretsen P, Pollock BG, Mulsant BH, Rajji TK, Mamo DC, Graff-Guerrero A. Threshold of Dopamine D2/3 Receptor Occupancy for Hyperprolactinemia in Older Patients With Schizophrenia. J Clin Psychiatry. 2016 Dec;77(12):e1557-e1563. doi: 10.4088/JCP.15m10538.
• Fervaha G, Caravaggio F, Mamo DC, Mulsant BH, Pollock BG, Nakajima S, Gerretsen P, Rajji TK, Mar W, Iwata Y, Plitman E, Chung JK, Remington G, Graff-Guerrero A. Lack of association between dopaminergic antagonism and negative symptoms in schizophrenia: a positron emission tomography dopamine D2/3 receptor occupancy study. Psychopharmacology (Berl). 2016 Oct;233(21-22):3803-3813. doi: 10.1007/s00213-016-4415-6. Epub 2016 Aug 24.

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