Bipolar disorder: Trimodal age-at-onset distribution

Area of Science:

• Psychiatry
• Mental Health Research
• Clinical Psychology

Background:

• Bipolar disorder (BD) is a chronic mental health condition associated with significant morbidity and mortality.
• Age at onset (AAO) is a critical factor for potentially identifying distinct subgroups within the BD population.
• Systematic research defining BD AAO subgroups is currently lacking.

Purpose of the Study:

• To systematically assess and define age at onset (AAO) subgroups for bipolar disorder (BD).
• To establish a framework for future research and inform clinical treatment strategies for BD based on AAO.
• To investigate the distribution patterns of AAO in individuals diagnosed with bipolar disorder.

Main Methods:

• A comprehensive systematic literature search was conducted across multiple databases including Cochrane, PsycINFO, MEDLINE, Embase, CINAHL, Scopus, Proquest, Google Scholar, and BIOSIS Previews.
• Included studies were original quantitative research published in English, focusing on age at onset in bipolar disorder.
• Data from 21 studies, encompassing 22,981 BD participants, were analyzed to determine AAO distributions.

Main Results:

• Analysis of 21 studies (n=22,981) revealed varying age at onset (AAO) distributions in bipolar disorder (BD).
• A trimodal AAO distribution (early, mid, late onset) was identified in 67% of studies (n=13,626).
• A bimodal AAO distribution (early, late onset) was found in 24% of studies (n=1,422), with cohort effects influencing the model.

Conclusions:

• The findings support conceptualizing bipolar disorder (BD) age at onset (AAO) subgroups based on broad life stages.
• Defining these BD AAO groups can enhance treatment approaches and provide a structured foundation for investigating disease onset mechanisms.
• Further research is warranted to explore the implications of these AAO subgroups in understanding bipolar disorder.