Long-term stability of measuring D(2) receptors in schizophrenia patients treated with antipsychotics

Background While antipsychotic-free schizophrenia patients showed a high degree of within-subject variability in dopamine D 2 receptor density over 6–24 months, no study has examined the long-term stability of D 2 receptor measures in medicated patients. Methods Four schizophrenia patients receiving a stable dose of risperidone underwent [ 11 C]raclopride positron emission tomography scans on two occasions 5–14 months apart. Results Plasma risperidone levels were found to be consistent between scans, and consistencies of nondisplaceable D 2 binding potential and D 2 occupancy were good. Conclusions The finding supports the validity of quantification of D 2 receptor binding in longitudinal PET studies of medicated patients with schizophrenia.