Am J Psychiatry 1981; 138:1106-1109
Copyright © 1981 by American Psychiatric Association
Effect of case definition on affective disorder rates
W Coryell, G Winokur and NC Andreasen
In a preliminary analysis by the NIMH-Clinical Research Branch
Collaborative Program on the Psychobiology of Depression the lifetime rate
of affective illness among 1,090 interviewed relatives of depressed and
manic probands was considerably lower in Iowa than in the other four
centers. Among various affective disorder diagnoses, only primary unipolar
depression was significantly less frequent in Iowa. This rate difference
decreased with increasingly restrictive case definitions. Possible
determinants of the low depression rate in Iowa will be investigated; the
present data illustrate the importance of case definition in the
interpretation of future findings.
