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Title: D2 receptor blockade by risperidone correlates with attention deficits in late-life schizophrenia
Authors: Uchida, Hiroyuki
Rajji, Tarek K.
Mulsant, Benoit H.
Kapur, Shitij
Pollock, Bruce G.
Graff-Guerrero, Ariel
Menon, Mahesh
Mamo, David
Keywords: Aging -- Health aspects
Cognition -- Data processing
Issue Date: 2009
Publisher: Lippincott Williams & Wilkins
Citation: Uchida, H., Rajji, T. K., Mulsant, B. H., Kapur, S., Pollock, B. G., Graff-Guerrero, A., ... & Mamo, D. C. (2009). D2 receptor blockade by risperidone correlates with attention deficits in late-life schizophrenia. Journal of Clinical Psychopharmacology, 29(6), 571-575.
Abstract: The negative impact of antipsychotic drugs on attention is expected to be greater in late-life schizophrenia because of the age-related changes in the dopamine receptor reserve. The objective of this study was to examine the relationship between dopamine D2 receptor blockade by risperidone and the cognitive function in late-life schizophrenia. Subjects with schizophrenia or schizoaffective disorder aged 50 or older who were receiving risperidone completed a [11C]raclopride positron emission tomography scan to measure D2-binding potential in the striatum. The D2 receptor blockade by risperidone was calculated using age-corrected measures from healthy individuals and region of interest analysis of dynamic positron emission tomography data coregistered to the subjects' magnetic resonance imaging scans. Cognitive function was assessed using a battery of neuropsychological tests that included the Dementia Rating Scale-2 (DRS). Eleven subjects (mean ± SD age, 64 ± 8 years) participated in this study. The mean ± SD D2 receptor blockade was 69% ± 14% (range, 34%-80%). The age-corrected score on the attention subscale in the DRS was negatively correlated with the D2 receptor blockade. The DRS attention subscale score was lower in the subjects who experienced 74.9% or higher D2 blockade (median value, corresponding to a daily risperidone dose of >3.0 mg) than in those who did not. Although a causal attribution cannot be made in light of the cross-sectional nature of this study, the results suggest the critical importance of identifying the lowest effective dose of antipsychotic drugs in older patients with schizophrenia.
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