Frontal slow-wave activity as a predictor of negative symptoms, cognition and functional capacity in schizophrenia

Background Increased temporal and frontal slow-wave delta (1-4 Hz) and theta (4-7 Hz) activities are the most consistent resting-state neural abnormalities reported in schizophrenia. The frontal lobe is associated with negative symptoms and cognitive abilities such as attention, with negative symptoms and impaired attention associated with poor functional capacity. Aims To establish whether frontal dysfunction, as indexed by slowing, would be associated with functional impairments. Method Eyes-closed magnetoencephalography data were collected in 41 participants with schizophrenia and 37 healthy controls, and frequency-domain source imaging localised delta and theta activity. Results Elevated delta and theta activity in right frontal and right temporoparietal regions was observed in the schizophrenia v. control group. In schizophrenia, right-frontal delta activity was uniquely associated with negative but not positive symptoms. In the full sample, increased right-frontal delta activity predicted poorer attention and functional capacity. Conclusions Our findings suggest that treatment-associated decreases in slow-wave activity could be accompanied by improved functional outcome and thus better prognosis.