Dopamine D2 and D3 Receptor Occupancy and Clinical Response in Older Patients With Schizophrenia
Status:
Active, not recruiting
Trial end date:
2020-12-01
Target enrollment:
Participant gender:
Summary
This study will provide information regarding dopamine D2/D3 occupancy related with
clinical/adverse effects in older people with schizophrenia and schizoaffective disorder. The
results of this study will also show an appropriate dose range in order to evade undesirable
adverse effects while deriving therapeutic effects, which will directly serve to guide
physicians in clinical practice. Furthermore, the findings of this study will elucidate
mechanisms underlying older people's increased sensitivity to antipsychotic drugs. In
addition, the contribution of D2 and D3 in mediating antipsychotic response will be
contrasted, using 2 radiotracers, which has never been tested in an older population.
The hypotheses are as follows: First, clinical response (i.e., a ≥ 20% decrease in the Brief
Psychiatric Rating Scale total score) will be achieved in older patients with occupancy that
is lower than the threshold of 60% in historical young controls. Second, prolactin elevation
and EPS will be detected in older patients with occupancies that are lower than the
thresholds of 72 and 78% reported in historical young controls. Third, dopamine D2 receptor
occupancy will be inversely correlated with subjective well-beings. Fourth, the binding
potential and receptor occupancy will be at least 20% lower with [11C]-(+)-PHNO than with
[11C]-raclopride in the caudate/putamen. Fifth, the binding of [11C]-(+)-PHNO in the globus
pallidus will be higher than that of [11C]-raclopride.