Differentiation between major and minor depression.

Though the concept of Major Depression was generated by clinicians using depressed inpatients as models, a polydiagnostic study in 600 psychiatric inpatients with heterogenous psychological disturbances revealed that all six competing operational definitions of Major Depression (including DSM-III-R and ICD-10) were too restrictive to serve as a general concept of depression. Another polydiagnostic study in 500 primary care outpatients showed that more than two-thirds of all non-chronic depressed cases were below the severity threshold of Major Depression: these patients are classified as Depression Not Otherwise Specified (NOS) by DSM-III-R. Loosening of the over-restrictive time criteria would broaden the concept of Major Depression so as to meet the requirements of a general concept of depression, while the definition of Minor Depression below the threshold of Major Depression would add to a reduction of cases of NOS Depression by more than 80%. For the evaluation of antidepressant drugs in outpatient samples, we propose that patients with these modified definitions of Major and Minor Depression be included, provided they meet a minimum severity criterion of 13 or more points on the Hamilton Depression Scale; four-fifths of the modified Major Depression group and one-third of the Minor Depression group do in fact meet this criterion.