The nature of the relationship of psychomotor slowing with negative symptomatology in schizophrenia

INTRODUCTION: Psychomotor slowing is an important feature of schizophrenia and the relation with negative symptoms is not fully understood. This study aims, first, to investigate the association between negative symptoms and psychomotor slowing. Second, we want to investigate whether fine motor slowing reflects clinically observable gross motor slowing. METHODS: In 53 stabilised adult patients with schizophrenia, negative symptoms were assessed using the Positive and Negative Syndrome Scale negative subscale (PANSS-N) with two calculated factors entering the analysis: an expressivity factor and a volitional factor. Psychomotor slowing was assessed by using a modified version of the Salpêtrière Retardation Rating Scale, the Finger Tapping Test, and a writing task measuring fine psychomotor slowing. RESULTS: Negative symptomatology is associated with difficulties in the initiation of fine motor movements, r=.334, p<.05, whilst planning and execution are not. The volitional factor, r=-.407, p=.005, but not the expressivity factor, r=.060, p=.689, is significantly associated with psychomotor slowing. No associations between fine and clinically observable gross psychomotor functioning were found. CONCLUSIONS: These findings indicate that higher values of negative symptomatology-more specifically the volitional deficit cluster-affect motor initiation, indicating a heterogeneity in the PANSS-N factorial structure, and that gross and fine psychomotor functioning are affected independently.