PSYCHOMOTOR SLOWING, NEGATIVE SYMPTOMS AND DOPAMINE-RECEPTOR AVAILABILITY - AN IBZM SPECT STUDY IN NEUROLEPTIC-TREATED AND DRUG-FREE SCHIZOPHRENIC-PATIENTS

Anhedonia and psychomotor slowing in schizophrenia have been attribute d to a dysfunction of dopaminergic neurotransmission. To differentiate between disease and drug-induced negative symptoms, we examined eight drug-free and eight neuroleptic-treated schizophrenic patients. Posit ive and negative symptoms and extrapyramidal side effects were assesse d using standardized rating scales (PSAS, AMDP, SANS). 'Reaction time' and 'motor speed' were measured using a computer-aided system and str iatal dopamine D-2/D-3 receptor availability was assessed using [I-123 ]IBZM SPECT. Psychomotor reaction time, parkinsonism, affective flatte ning and avolition were increased in treated patients relative to the untreated cohort and were negatively correlated with dopamine D-2/D-3 receptor availability. Significant positive correlations were found be tween parkinsonism and affective flattening and between psychomotor sl owing and avolition. Positive symptoms were not significantly associat ed with striatal IBZM binding. These findings support the hypothesis t hat neuroleptic-induced dopamine D-2/D-3 blockade in the striatum can mimic certain negative symptoms, such as affective flattening and avol ition, and indicates that psychomotor testing may be helpful in differ entiating between disease and drug-induced negative symptoms. (C) 1998 Elsevier Science B.V. All rights reserved.