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.