Brain Sources for change-detection: an ERP study in patients at the outbreak of early onset schizophrenia and 15 years later

Abstract

BACKGROUND: Severer illness, poorer prognosis and impaired brain structure are reported for patients with an early-onset of schizophrenia1,2. Is this reflected in early stimulus processing? METHODS: This study compares an electrophysiological measure of automatic, auditory attention-related function and its sources in the brain for 19 patients (17.5 years) at onset, and 17 patients 15 years after an early onset with age-matched healthy subjects. RESULTS: Mismatch Negativity (MMN), recorded from 32 sites during a simple visual vigilance task, was associated with a rare tone shorter than the standard. Brain electrical source analysis (BESA) confirmed bilateral frontal and temporal lobe dipoles3. Both patient groups showed a smaller MMN than the controls. There were several signs of illness progression in the older patient group: (a) a visual vigilance decrement was only evident in the older patients, (b) the left superior temporal source was weaker, (c) the left cingulate source changed orientation, (d) the right inferior/mid-frontal source was active later. This illness-related progression of a cognitive impairment is consistent with a neurodevelopmental hypothesis4, initial structural impairments in young patients5 contrasting with more variable or sporadic changes in those with a later onset6,7.