title: Genetic and state variables of neurocognitive dysfunction in schizophrenia: a twin study.
abstract: To characterize the familiality of cognitive dysfunction in schizophrenia, we studied performance on three tasks (visuospatial attention; visuolinguistic conflict, arrow-word; and Wisconsin Card Sorting Test [WCST]) by monozygotic (MZ) and dizygotic (DZ) twin pairs discordant for schizophrenia. The subject sample consisted of six MZ twin pairs, nine DZ twin pairs, and one MZ and one DZ nonschizophrenia cotwin of a patient with schizophrenia. There were two sources of cognitive dysfunction: a nonheritable, state component and a heritable, trait component. Deficits surfaced during the WCST in nonschizophrenia MZ cotwins; this impairment resolved following training in nonschizophrenia MZ cotwins, but not in the probands with schizophrenia, who performed abnormally in all tasks. The results suggest that nonheritable protective factors modulate the specific, plastic, and sometimes subtle neurocognitive deficits related to the schizophrenia genotype.
authors.affiliation: University of Minnesota, Department of Psychiatry, Brain Sciences Center, Veteran Affairs Medical Center, Minneapolis, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Pardo
authors.forename: M A
authors.initials: MA
authors.lastname: Knesevich
authors.forename: G P
authors.initials: GP
authors.lastname: Vogler
authors.forename: J V
authors.initials: JV
authors.lastname: Pardo
authors.forename: B
authors.initials: B
authors.lastname: Towne
authors.forename: C R
authors.initials: CR
authors.lastname: Cloninger
authors.forename: M I
authors.initials: MI
authors.lastname: Posner
mesh_terms: D000328:Adult; D001288:Attention; D003072:Cognition Disorders / Q000150:complications / Q000235:genetics*; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000150:complications / Q000235:genetics*