Does Mood Disorder Questionnaire identify sub-threshold bipolarity? Evidence studying worsening of quality of life.

Objective: It is debated whether the Mood Disorder Questionnaire (MDQ) can generate false positives by screening other disorders as bipolar, or identify sub-threshold bipolarity. The aim is to verify if Quality of Life (QoL) impairment in MQD positives in the community is due to MDQ positivity itself, or to psychiatric diagnosis associated with MDQ positivity (supporting the former hypothesis).

Method: Community survey. Sample randomized after stratification of the adult population in the records of seven Italian regions.

Tools: MDQ; Short Form Health Survey (SF-12); semi-structured clinical interview carried out by clinicians.

Results: Positives at MDQ show worsening QoL with an attributable burden of 2.8 ± 1.8 lower than in MDD (5.6 ± 3.6, p < 0.001) or Eating Disorders (4.4 ± 6.6, p < 0.03) and similar to Panic Disorder (2.9 ± 0.9, p = 0.44). The burden is lower in the middle-aged (25-59 years) than in the young (18-24) (4.65 ± 4.5 vs 2.58 ± 2.0, p=0.007) or in the elderly (≥60) (4.12 ± 3.2; p = 0.024). In the elderly the burden is independent from comorbid psychiatric disorders.

Limitations: This is a preliminary study based on one survey not designed to test this specific hypothesis, thus its results have a heuristic value only.

Conclusions: The worsening of QoL due to positivity at MDQ is largely independent from comorbid conditions, supporting the hypothesis that MDQ positivity identifies a specific area of suffering that is "subthreshold" to the psychiatric diagnosis, and relevant for public health.