title: N400 abnormalities in late life schizophrenia and related psychoses.
abstract: The N400, an event-related brain potential (ERP) sensitive to semantic congruity, has been reported to have increased latency and/or reduced amplitude in young adults with schizophrenia. Little is known, however, regarding the N400 in older schizophrenia patients, especially those with late onset. We studied 18 middle-aged and elderly patients with schizophrenia and related psychoses (nine with early-onset psychosis (EOP) and nine with late-onset psychosis (LOP)), and nine normal comparison (NC) subjects. Subjects read words which were semantically incongruent (50%) or congruent (50%) with a preceding spoken phrase which defined either an antonymic or categorical relationship. The LOP group had a significantly later peak latency of the N400 congruity effect compared to the NC group. Seven of 18 psychosis patients, but none (0/9) of the normal subjects, had an abnormal latency or amplitude (p = 0.04), measured at T6 (right temporal). Smaller amplitudes were associated with more severe negative symptoms (rp = 0.58; p = 0.01). N400 abnormalities in older schizophrenia patients likely reflect abnormal processing of semantic information.
authors.affiliation: University of California San Diego, Department of Neurosciences, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Olichney
authors.forename: V J
authors.initials: VJ
authors.lastname: Iragui
authors.forename: M
authors.initials: M
authors.lastname: Kutas
authors.forename: R
authors.initials: R
authors.lastname: Nowacki
authors.forename: D V
authors.initials: DV
authors.lastname: Jeste
mesh_terms: D000328:Adult; D000368:Aged; D001143:Arousal / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D002908:Chronic Disease; D004292:Dominance, Cerebral / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D012016:Reference Values; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D012660:Semantics; D013067:Speech Perception / Q000502:physiology*