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

IntroductionPsychomotor 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.MethodsIn 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 Salpetriere Retardation Rating Scale, the Finger Tapping Test, and a writing task measuring fine psychomotor slowing.ResultsNegative 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.ConclusionsThese findings indicate that higher values of negative symptomatologymore specifically the volitional deficit clusteraffect motor initiation, indicating a heterogeneity in the PANSS-N factorial structure, and that gross and fine psychomotor functioning are affected independently.