The association between early parental loss and diagnosis in the Iowa 500.

While a number of studies have found an association between the experience of death of a parent during childhood and the later development of depression as an adult, few of these studies have controlled for possible confounders such as social class, sibship size, parental age at birth, and the patient's age at admission. The results of several studies that do control for such confounders have been negative. The authors investigated the frequency of parental loss and parental death among 129 depressives, 155 schizophrenics, and 63 manics from the Iowa 500 data base. Using a logistic regression to control for confounders, depressives are found to experience early maternal death 3.4 times more frequently than the schizophrenics and 2.1 times more frequently than the bipolars. The failure to confirm other hypotheses and possible implications are discussed.