[The staging model (or evolutionary stages) applied to bipolar disorder]

In psychiatry, clinical staging raises awareness of the need to understand disease trajectories and heterotypic continuity; it draws attention to individuals at risk of developing disorders, such as those with a family history or subsyndromal presentations; and it actively promotes greater attention to prevention strategies and interventions for individuals at ultra-high risk of developing a severe mental disorder. Staging paradigms have been increasingly applied in early intervention in psychoses, but there are issues in broadening the scope of clinical staging to the more prevalent affective disorders. For example, it is potentially more complex to devise a model that considers the varying clinical presentations of the late prodromal stage of bipolar disorder and where to locate depressive episodes that precede the first manic episode and how to describe subthreshold manic syndromes, especially hypomania. The above issues might be resolved if we had a greater understanding of the risk factors, biomarkers or endophenotypes for the onset and progression of bipolar disorder. This level of understanding is not yet available in psychiatry, but clinical staging may help us improve our knowledge of the pathophysiological correlates of disease progression and reduce our over-reliance on cross-sectional assessments of symptoms in bipolar disorders.