Antecedent Validators Demographic factors Age at onset At the onset of illness the DD cases are older than the schizophrenics: the commonest age at onset being oldest age at onset for the persecutory type and the youngest for the somatic type. Age at admission: The peak age for first admission for the DD is between 40-49 years followed by age at first presentation being 30-39 years (Table 3); in contrast first admissions for schizophrenia peak at 20-29 years or 25-34 years. The differ- ence in age at first admission between DD and affective disorders is much less. Ser ratio: Recent studies have reported that for DD first admissions females outnumber males (Table 3); some studies reported that percentage wise cohorts of DD had less males compared to schizophrenia, and more males compared to affective illness. Marital Status: At admission 32% DD cases were found to be never married (Table 3) compared to 50-69% patients with schizophrenia, the comparable data for affective disorder subjects was similar. Educational History. The DD cases were reported to be more poorly educated than cases with affective illness (Kendler 1982. of the DD cases respectively to be self supporting and with no major period without work compared to 31% and 30% respectively of the cases with schizophrenia. Winokur (977 so reported the DD cases to have a satisfactory