Delayed early face processing in bipolar disorder.

Bipolar disorder primarily encompasses mood symptom states of depression and mania separated by symptom-free euthymia, and patients also exhibit cognitive deficits that include face processing. However, there is minimal extant event-related potential (ERP) research investigating the time course of these impairments. The aim of the present study was to contribute to a greater understanding of the specific stages of face processing that are impaired in bipolar disorder. Bipolar and age-matched and sex-matched control individuals completed an emotional go/no-go paradigm involving happy and sad face stimuli during ERP acquisition. Amplitudes and latencies of frontocentral P80, N120 and vertex positive potential (VPP) ERP components were analysed in response to 'go' stimuli. Across groups, VPP latencies were reduced in response to sad compared with happy face stimuli. Between groups, individuals with bipolar disorder demonstrated overall increased latencies in P80 and VPP ERP components. Current and previous studies suggest that patients with bipolar disorder exhibit early visual processing deficits, but the present study contributes new evidence of a deficit in the visual P80 ERP. Delayed neural responses may be an ERP correlate of white matter deficits that have previously been identified. Furthermore, implications for early visual impairments may involve behavioural symptoms downstream.