Psychometric validation and clinical validity of the Minor Melancholia Mood Checklist (MMCL-32).

Background: The Minor Melancholia Mood Checklist (MMCL-32) was developed to identify sub-threshold states of major depression. The MMCL-32 can be considered as the counterpole to the Hypomanic Check List (HCL-32).
Methods: Principal component analysis (PCA) without rotation was used to identify a bidirectorial principal component. To evaluate the clinical validity of the bidirectorial factors, with reference to brief recurrent depression, the Bech-Rafaelsen Melancholia Scale was used.
Results: We included 59 patients with bipolar I disorder (SCID criteria) and 57 patients with unipolar depression (more than one major depressive episode without hypomanic or manic episodes). They were all outpatients, but had recently been discharged from inpatient treatment. The PCA identified two contrasting factors: 17 items with negative loadings (psychasthenic depression factor) and 15 items with positive loadings (cognitive depression factor). When PCA was applied exclusively to the bipolar patients, 5 items within the cognitive factor were identified. When applied exclusively to the unipolar patients, 5 items within the psychasthenic factor were identified. The non-remitted bipolar patients scored higher on the cognitive factor (P=0.01) than the remitted. On the psychasthenic factor (P=0.06), the non-remitted unipolar patients scored higher than the remitted patients.
Conclusion: The MMCL-32 was found psychometrically valid in measuring sub-threshold states of major depression with rather specific factors for bipolar and unipolar depression. Focusing on these factors could be a clinical aid to distinguish patients at risk of developing a bipolar course.
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