A critique of the Finnish adoptive family study of schizophrenia

This paper evaluates the ongoing Finnish Adoptive Family Study of Schizophrenia. The Tienari, Lahti et al. (1987) study is the most recent attempt to use adoptees as a way of testing the hypothesis chat: schizophrenia carries a genetic component, and the purpose here is to present what is probably the first in-depth critical analysis of its findings. The published reports of Tienari and associates are the primary focus of analysis, while problems with other schizophrenia adoption studies using similar research designs are also discussed. Because of factors including the selective placement of adoptees, the low variance explained by the two major hypothesized predictor variables for schizophrenia, the invalidity of the schizophrenia spectrum concept, and the failure to find an index schizophrenia rate greater than general population expectations, it is concluded that the Finnish study cannot be regarded as having produced evidence in favor of the genetic theory of schizophrenia.