Genetic theories and the validation of psychiatric diagnoses: Implications for the study of children of schizophrenics

Argues that the success of prospective methods for studying the development of schizophrenia in those few offspring of schizophrenics who also become schizophrenic (high-risk method) depends on using valid diagnostic criteria for selecting the parent probands. Data from a high-risk study in which the affected parents were diagnosed by 5 clinicians are used to illustrate how different diagnostic standards affect the comparison of high-risk samples and control samples of children of other psychiatric patients. Publicly reporting careful assessments of affected parents will also facilitate comparisons among different high-risk samples and will allow estimates of the risks for individuals within each high-risk sample. Genetic theory and empirical data suggest that children with severely affected parents and children with many affected relatives will have the highest risks, while samples of children with only 1 mildly affected parent may have risks that approach the population base rates. Genetic theory further suggests that some children of validly diagnosed schizophrenics will have no genetic risk for schizophrenia, and some of those who do have the genetic predisposition will enjoy a lifetime of adequate mental health even without intervention, thus confounding the effort of high-risk research to validate indicators of the high-risk genotype with follow-up status. High-risk researchers are cautioned against premature implementation of intervention strategies based on unvalidated indicators of the risks to individuals. (21/2 p ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).