The Bipolar Prodrome: Meta-Analysis of Symptom Prevalence Prior to Initial or Recurrent Mood Episodes

The aim of this study was to meta-analyze the prevalence of symptoms before an initial mood episode of bipolar disorder (BD) and the prevalence of subthreshold symptoms before a BD mood episode recurrence, to facilitate early identification and prevention.

Systematic literature reviews were conducted in PsycINFO and PubMed for prospective or retrospective studies reporting on the prevalence and longest duration of symptoms before an initial or recurrent mood episode of BD. Random effects meta-regression explored whether geographic location, age, percentage of female individuals, and study quality moderated the overall prevalence.

In 11 studies (n = 1,078), the prodrome preceding an initial mood episode lasted 27.1 ± 23.1 months (range, 4.6-130 months). In 10 studies (n = 1,000), the subthreshold symptoms preceding a recurrent mood episode lasted 1.0 ± 0.9 months (range, 0.5-1.3 months). The most common symptoms were largely consistent with diagnostic criteria symptoms associated with the subsequent mood polarity for both the initial prodrome and the period prior to a recurrent mood episode. Few moderators of symptom prevalences emerged, and significant heterogeneity remained.

The initial prodromal period is sufficiently long and characterized by symptoms of the subsequent mood episode to make early identification and intervention programs feasible. Conversely, the period of subthreshold symptoms before a recurrent mood episode is short, mandating adequate psychoeducation of patients and families, monitoring of changes in sleep and activity, plus sufficiently frequent follow-up visits to identify patients before a mood episode recurrence. Future prospective investigations, designed to address the identified shortcomings in the extant literature, are needed to identify more clinically applicable information.