Validity of the family history method in relatives of gerontopsychiatric patients.

It was the aim of the present study to evaluate the validity of the family history method in relatives of a sample of elderly subjects. A total of 201 relatives of patients and 89 relatives of control subjects were interviewed directly using the Composite International Diagnostic Interview and the Structured Interview for the Diagnosis of Dementia of the Alzheimer Type, Multi-infarct Dementia and Dementias of other Etiology. At least one relevant other could provide family history information on a respective subject. Family history information for psychiatric disorders including dementia (DSM-III-R) was neither accurate, nor sensitive (10 to 40%), but highly specific (> 95%). The sensitivity of the family history for dementia and depression increased in relation to the severity of the disorder. Relatives of patients were better informants than relatives of controls (at least for the presence of any psychiatric disorder). The use of several informants only slightly improved the sensitivity of the family history, without reducing the specificity to a significant extent. The combination of different sources of information may serve to reduce information biases. The evaluation of possible biases in future family studies is required to draw adequate conclusions from differences in familial loads.