| Unipolar versus bipolar disorder |
| Psychotic versus nonpsychotic |
| Cognitive impairment versus not impaired |
| Onset in late life versus in early life |
| Positive versus negative family history |
| Primary versus secondary disorder |
| Endogenous versus non-endogenous |
| Melancholic versus non-melancholic disorder |
| DST positive versus DST negative |
| Psychomotor retardation versus not retarded |
| Seasonal versus non-seasonal |
| Typical versus atypical |
| With versus without obsessive-compulsive symptoms. |
published 2000