Lifetime psychotic symptoms assessed with the DIS.

Data on a lay interviewer's use of the Diagnostic Interview Schedule (DIS) to ascertain lifetime psychotic symptoms in patients where these experiences have been previously documented is reported. The subjects in this study had been identified as patients 11 years previously and had participated in several followup research interviews with research psychiatrists. Frequent failure to recall and/or report psychotic symptoms in these patients suggests this technique will seriously underestimate the lifetime occurrence of psychotic symptoms.