Screening for bipolar disorders: A public health issue.

INTRODUCTION: Bipolar disorder (BD) is a public health issue; it is one of the leading causes of disability and its late diagnosis heightens the impact of the condition. Screening tools for early detection could be extremely useful.
METHODS: Narrative review on screening of BD.
RESULTS: Screening questionnaires have high sensitivity but relatively low specificity if DSM diagnoses are taken as the "gold standard". Critics maintain that an excess of false positives makes such tools unnecessary for identifying cases and of little use in screening studies consisting of two phases. However, "positive" screening was frequently homogeneous with BD in terms of gender, age, level of distress, low social functioning and employment rate, comorbidity with alcohol and substance abuse, heavy recourse to health care, use of mood stabilizers and antidepressants, risk of suicide attempts, and high recurrence of depressive episodes. While none of these components is pathognomonic of BD, their co-occurrence could identify subthreshold "cases". The studies reviewed found positivity at screening to be associated with impaired quality of life, even without BD and independently of comorbidity. Patients with a neurological disease and positive at screening show homogenous brain lesions, different from those of patients screening negative.
CONCLUSIONS: The results are coherent with the hypothesis that positivity identifies a bipolar spectrum of clinical and public health interest, including sub-threshold bipolar cases, which do not fulfil the diagnostic criteria for BD.