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Subtypes of schizophrenia — evidence from a twin‐family study
Author(s) -
Onstad S.,
Skre I.,
Torgersen S.,
Kringlen E.
Publication year - 1991
Publication title -
acta psychiatrica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.849
H-Index - 146
eISSN - 1600-0447
pISSN - 0001-690X
DOI - 10.1111/j.1600-0447.1991.tb03129.x
Subject(s) - proband , etiology , schizophrenia (object oriented programming) , concordance , psychosis , first degree relatives , psychology , twin study , psychiatry , dizygotic twin , monozygotic twin , paranoid schizophrenia , family history , clinical psychology , medicine , genetics , heritability , biology , gene , mutation
In a combined twin‐family study, the concordance for subtype of schizophrenia was investigated. The sample included 31 monozygotic (MZ) and 28 dizygotic (DZ) twin probands fulfilling the criteria of DSM‐III‐R schizophrenia. Their co‐twins and first‐degree relatives were personally interviewed and diagnosed in accordance with DSM‐III‐R. Any twin or relative diagnosed as schizophrenic was subclassified as either paranoid or nonparanoid. Schizophrenia was more often observed in co‐twins of MZ probands with nonparanoid schizophrenia than in MZ probands with paranoid schizophrenia, indicating a stronger genetic influence in nonparanoid schizophrenia. Fifteen MZ pairs were concordant for schizophrenia, and 13 of these pairs were also concordant for subtype. Such a relationship was not observed in the first‐degree relatives with schizophrenia. Our results indicate a complex etiology of subtypes in schizophrenia, and to some extent the etiology of subtypes may differ from the etiology of schizophrenia.