Lateralized movement-related potential amplitudes differentiate between schizophrenia/schizoaffective disorder and major depression

ObjectiveTo examine whether deficits in focal lateralized motor system activation would differentiate between subjects with schizophrenia/schizoaffective disorder and subjects with a major depressive episode. Reductions of Bereitschaftspotential amplitude have been described for both diagnostic groups.MethodsWe analyzed multi-channel lateralized movement-related potentials (LMRP) during choice reaction movements in 16 schizophrenic/schizoaffective patients in partial remission with predominant negative symptoms, 18 patients with a non-psychotic major depression and two healthy control groups age-matched to the respective patient groups (20/23 subjects).ResultsA significant reduction of lateralized potentials over the (pre-)motor areas immediately preceding and around movement execution was found only in subjects with schizophrenia/schizoaffective disorder but not with a major depressive episode. Reduced LMRP amplitudes correlated with negative symptoms (SANS score). Other movement stages (preceding response-locked ‘contingent negative variation’ during response selection and post-movement evaluation during motor postimperative negative variation) were not affected in the same way.ConclusionsDeficits in focal motor cortex activation during movement execution may reflect rather schizophrenia-specific deficits in fronto-striatal circuits. A general lack of drive and depressed mood did not alter the degree of lateralization of motor activation during movement execution.SignificanceLateralization of movement-related potentials could differentiate psychotic from non-psychotic disorders on the group level.

► Lateralized movement-related potentials were reduced in subjects with schizophrenia/schizoaffective disorder compared to subjects with a major depressive episode.
► The time interval around movement execution was affected.
► Deficits in lateralized primary motor cortex activation during the command to muscle contraction may distinguish schizophrenia/schizoaffective disorder from non-psychotic forms major depression.