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Tienari , 1991. Mothers with schizophrenia. Kirby Throop & Ali Hollis. Background data from family, twin and adoption studies show overwhelming evidence of a substantial genetic component in schizophrenia. . Procedure.
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Tienari, 1991 Mothers with schizophrenia Kirby Throop & Ali Hollis
Background data from family, twin and adoption studies show overwhelming evidence of a substantial genetic component in schizophrenia.
Procedure • From a sample of almost 20,000, a number of 361 adoptive families containing the adopted-away offspring of a schizophrenia or control mother had been contacted for field study. • The adoptive families were investigated thoroughly by joint and individual interviews and psychological tests. Biologic parents were also interviewed and tested.
Findings Tienari found that: • 15 psychotic adoptees have been ascertained, of whom 13 are offspring of schizophrenia mothers (13/144 = 9.1%) and 2 are offspring of control mothers (2/178 = 1.1%). • Of the 13 psychotic adopted-away offspring of schizophrenia mothers, by DSM-HI-R criteria, 7 had schizophrenia, 2 had schizophreniform disorder, 2 had delusional disorder, and 2 had psychotic bipolar illness. • Both of the psychotic offspring of control mothers had schizophrenia. Therefore, the prevalence of schizophrenia is also significantly greater in offspring of index mothers (7/144 = 4.9%) than in offspring of control mothers.
Conclusions • These results show a strong genetic link with schizophrenia, however, the concordance rates are not 100%, which suggests that environmental influence is also involved. • Tienari’s findings also support the importance of genetic factors and is evidence against nurture.
Further • This adoption study has also examined the role of familial-environmental factors in the etiology of schizophrenia and found a substantial correlation between the functioning of the adoptive family and the psychiatric outcome in the adoptee. Of particular interest, this relationship was greatest when the adoptee was an offspring of a schizophrenia mother. • These results are consistent with a model in which schizophrenia emerges when genetically susceptible individuals experience disruptive family environments. • However, most of the families were evaluated when the adoptees were well into adult life. • Therefore this observed correlation between adoptee and adoptive family functioning could also be due to disturbed adoptees creating disturbed families.