Objectives: Bipolar affective disorder (BD) is a multifactorial disorder with heterogeneous clinical presentations, in particular according to age at onset (AAO). The relevance of such an indicator has been discussed as a potential specifier in future nosographical classification.
Method: We summarize available evidence of admixture analyses and biomarkers in early onset BD.
Results: Numerous clinical arguments have led us to conclude that the early onset BD subgroup is clinically homogeneous, with particular, recurrent, and severe characteristics.Eight admixture studies have demonstrated the existence of 3 subgroups of patients with BD according to AAO (early, intermediate, and late AAO), with 2 cut-off points of 21 (21.33) [SD 1.41]) and 35 years (34.67 [SD 5.52]). Differential clinical features and outcome measures characterize the early onset subgroup: higher rate of suicide attempts, rapid cycling, alcohol and drugs misuse, psychotic symptoms, and comorbid anxiety disorders. This may partially explain the delayed diagnosis and late initiation of mood stabilizers. Genetic, biological, imaging, and cognitive arguments may be considered as potential markers in providing external validity of the existence of this early onset subgroup. Implementation of AAO in the algorithms of treatment may be discussed, although the level of proof for focused medication strategies remains to be consolidated.
Conclusion: Given the high frequency (44.80%) of early onset BD, awareness of clinicians should be stimulated to provide an early and accurate detection, preventive strategies, and possibly specific treatments.The forthcoming DSM-5 should include AAO as a specifier, given its relevance for course and outcome.