Therapeutic Window for Striatal Dopamine D2/3 Receptor Occupancy in Older Patients with Schizophrenia: A Pilot PET Study

摘要: Objective In younger patients with schizophrenia, positron emission tomography (PET) studies have identified a therapeutic window of striatal dopamine D 2/3 receptor occupancy 65%–80%. This type empirical information is not available in late life. Our primary aim was to assess the effect changes relative (RRO) on clinical outcomes this population. Design Open-label intervention. Setting Centre for Addiction and Mental Health, Toronto. Participants Subjects schizophrenia age 50 years or more who were clinically stable previously maintained oral risperidone than 6 months. Intervention A dose reduction up 40%, followed by 3-month follow-up. Measurements Dopamine RRO dorsal putamen assessed, using region interest analysis [ 11 C]raclopride PET scans, before after reduction. Clinical assessments included Positive Negative Syndrome Scale Simpson-Angus Scale. Results Nine subjects (mean ± SD age: 58 7 years; mean baseline dose: 3.4 1.6 mg/day) participated study. Extrapyramidal symptoms (EPS) present six associated 70% (range: 70%–87%). Following reduction, EPS resolved five subjects. Two experienced worsening at 52% less 50% RRO. Conclusion diminished RRO, which suggests lower older that patients. Although these findings be replicated larger sample, they important implications future drug development guidelines late-life schizophrenia.