Differential diagnosis between bipolar disorder (BD) and borderline personality disorder (BPD) is often challenging due to some overlap in symptoms and comorbidity of disorders. We investigated correlations in self-reported symptoms of BD and BPD in screening questionnaires at the levels of both total scores and individual items and explored overlapping dimensions.

The McLean Screening Instrument (MSI) for BPD and the Mood Disorder Questionnaire (MDQ) for BD were filled in by patients with unipolar and bipolar mood disorders (n = 313) from specialized psychiatric care within a pilot study of the Helsinki University Psychiatric Consortium. Pearson's correlation coefficients between total scores and individual items of the MSI and the MDQ were estimated. Relationships between MDQ and MSI were evaluated by exploratory factor analysis (EFA).

The correlation between total scores of the MDQ and MSI was moderate (r = 0.431, P < 0.001). Significant correlations were found between the MSI items of “impulsivity” and “mood instability” and all MDQ items (P < 0.01). In the EFA, the MSI “impulsivity” and “mood instability” items had significant cross-loadings (0.348 and 0.298, respectively) with the MDQ factor. The MDQ items of “irritability”, “flight of thoughts” and “distractibility” (0.280, 0.210 and 0.386, respectively) cross-loaded on the MSI factor.

The MDQ and MSI items of “affective instability”, “impulsivity”, “irritability”, “flight of thoughts” and “distractibility” appear to overlap in content. The other scale items are more disorder-specific, and thus, may help to distinguish BD and BPD.

We hypothesised that men and women who engage in extreme or high-risk sports would score higher on standardised measures of bipolarity and impulsivity compared to age and gender matched controls.

Four-hundred and eighty extreme or high-risk athletes (255 males and 225 females) and 235 age-matched control persons (107 males and 128 females) were enrolled into the web-based case-control study. The Mood Disorder Questionnaire (MDQ) and Barratt Impulsiveness Scale (BIS-11) were administered to screen for bipolarity and impulsive behaviours, respectively.

Results indicated that extreme or high-risk athletes had significantly higher scores of bipolarity and impulsivity, and lower scores on cognitive complexity of the BIS-11, compared to controls. Further, there were positive correlations between the MDQ and BIS-11 scores.

These results showed greater rates of bipolarity and impulsivity, in the extreme or high-risk athletes, suggesting these measures are sensitive to high-risk behaviours.

To use the Hypomania Checklist (HCL-32) and the Mood Disorder Questionnaire (MDQ), for detecting bipolarity in depressed patients.

One thousand and fifty-one patients fulfilling ICD-10 criteria for unipolar major depressive episode, single or recurrent, were studied. Patients were assessed using a structured demographic and clinical data interview, and by the Polish versions of the HCL-32 and MDQ questionnaires.

Hypomanic symptoms exceeding cut-off criteria for bipolarity by HCL-32 were found in 37.5% of patients and, by MDQ, in 20% of patients. Patients with HCL-32 (+) or MDQ (+) differed significantly from patients with HCl-32 (−) and MDQ (−) respectively, by being less frequently married, having more family history of depression, bipolar disorder, alcoholism and suicide, earlier onset of illness, and more depressive episodes and psychiatric hospitalizations. The percentage of patients resistant to treatment with antidepressant drugs was significantly higher in HCL-32 (+) vs HCL-32 (−) and in MDQ (+) vs MDQ (−): 43.9% vs 30.0%, and 26.4% vs 12.4%, respectively.

The results confirm a substantial percentage of bipolarity in major depressive disorder. Such patients have a number of clinical characteristics pointing on a more severe form of the illness and their depression is more resistant to treatment with antidepressants.