Dopaminergic Activity in Antipsychotic-naïve Patients Assessed with PET Before and After Partial Dopamine D2-receptor Agonist Treatment: Association with Psychotic Symptoms and Treatment Response

Abstract Background Dopamine activity has been associated with the response to antipsychotic treatment. Our study used a four-parameter model to test the association between the striatal decarboxylation rate of 18F-DOPA to 18F-dopamine (k3) and the effect of treatment on psychotic symptoms in antipsychotic-naive first-episode psychotic patients. We further explored the effect of treatment with a partial dopamine D2 receptor agonist (aripiprazole) on k3 and dopamine synthesis capacity (DSC) determined by the four-parameter model and by the conventional tissue reference method. Methods Sixty-two individuals (31 patients and 31 controls) underwent 18F-DOPA positron emission tomography at baseline and 15 patients were re-examined after six weeks. Clinical re-examinations were completed after six weeks (N=28) and six months (N=15). Symptoms were evaluated with the Positive and Negative Syndrome Scale. Results High baseline decarboxylation rates (k3) were associated with more positive symptoms at baseline (p Conclusions Striatal decarboxylation rate at baseline was associated with psychotic symptoms and treatment response. The strong association between k3 and treatment effect potentially implicate on new treatment strategies.