Dr Baldessarini has raised important questions about the variability in the rates of depression between our studies. Since similar questions undoubtedly will be raised by others, publication of our exchange of letters might help to clarify these issues. We expect that increased interest in the variability in the rates of disorders will be generated as data on ongoing family and epidemiologic studies are published.The major question is about the differences in the rates of affective disorders among relatives in our general population studies compared with those among the relatives in our family studies. Lifetime rates of major depression are higher in the general population studies than in the relatives of normal controls in the family studies because of the following qualifications.
Different Diagnostic Criteria.—
In the family study we used stricter modified criteria for major depression. We required a four-week instead of a twoweek duration of symptoms; a minimum