Positive correlation between reduction of handwriting area and D2 dopamine receptor occupancy during treatment with neuroleptic drugs.

We investigated the relationship between fine extrapyramidal-motor symptoms (reduction of handwriting area) and D2 dopamine receptor occupancy under neuroleptic treatment. The handwriting of 18 schizophrenic patients before and during treatment with typical (haloperidol, haloperidol decanoate) and atypical (clozapine, risperidone) neuroleptic drugs was examined. Data analysis of the handwriting's examination was carried out with a planimetric computer programme. At the time of the second test of handwriting, D2 receptor occupancy was determined with single photon emission tomography (SPET) using [(123)I]iodobenzamide ((123)I-IBZM). In all patients, a reduction of handwriting area and a D2 receptor occupancy were found. The correlation between reduction of handwriting area and D2 receptor occupancy for typical and atypical neuroleptic drugs was linear and statistically significant (r=0.9; P > 0.001). Our findings point to the possibility that the reduction of handwriting area may be used as a clinical indicator of D2 receptor occupancy under treatment with neuroleptic drugs.