Efficiency of working memory encoding in twins discordant for schizophrenia.

TitleEfficiency of working memory encoding in twins discordant for schizophrenia.
Publication TypeJournal Article
Year of Publication2009
AuthorsBachman, P, Kim J, Yee CM, Therman S, Manninen M, Lönnqvist J, Kaprio J, Huttunen MO, Näätänen R, Cannon TD
JournalPsychiatry research
Date Published2009 Nov 30
KeywordsAnalysis of Variance, Contingent Negative Variation, Diseases in Twins, Electroencephalography, Female, Humans, Magnetoencephalography, Male, Memory Disorders, Memory, Short-Term, Middle Aged, Neuropsychological Tests, Psychiatric Status Rating Scales, Reaction Time, Schizophrenia, Schizophrenic Psychology

It has been proposed that patients with schizophrenia and some of their relatives suffer from reduced neurocognitive efficiency, increasing their sensitivity to experimental task demands. The present study evaluated such a possibility during performance of a working memory task by schizophrenia patients and their co-twins along with a healthy control sample. Electrophysiological data were obtained from sets of nine twin pairs (monozygotic and dizygotic pairs collapsed) discordant for a diagnosis of schizophrenia and from nine matched healthy control twin pairs, during administration of a variable-load spatial working memory task. Event-related potentials (ERPs) were measured immediately after memory set onset and during a delay period. For correctly performed trials, slow-wave ERP activity measured during the late stimulus encoding and delay periods exhibited a significant Diagnostic Group-by-Memory Load interaction, with schizophrenia patients showing a differentially strong load effect. Patients' co-twins displayed an intermediate level of load sensitivity while healthy controls showed no significant load effect. These results support an inefficiency model of neurocognitive dysfunction in schizophrenia, a pattern that appears to be related to the pathogenesis and inheritance of the disorder. Furthermore, this inefficiency appeared during the late stimulus encoding stage of working memory functioning, possibly reflecting disruptions in stimulus representation consolidation.

Alternate JournalPsychiatry Res