Genetic and state variables of neurocognitive dysfunction in schizophrenia: A twin study

Patricia J. Pardo, Mary Ann Knesevich, George P. Vogler, Jose V Pardo, Bradford Towne, C. Robert Cloninger, Michael I. Posner

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)459-477
Number of pages19
JournalSchizophrenia bulletin
Issue number2
StatePublished - 2000


  • Attention
  • Cognition
  • Neuropsychology
  • Schizophrenia
  • State
  • Trait
  • Wisconsin Card Sorting Test


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