Onset-age of bipolar disorders at six international sites

Onset-age is a stable characteristic of bipolar disorder (BPD) patients of clinical and probable psychobiological importance, but large pooled clinical samples from multiple sites employing modern diagnostic criteria to quantify onset-age remain rare.

We pooled diagnostic, demographic, and clinical data from 1566 BPD patients from six international sites (5 European, 1 US) to compare onset-ages in subgroups.

Median+/-IQR onset in 1090 BP-I patients was 5.8 years younger than 476 BP-II cases (24.3+/-18.3 vs. 30.1+/-13.8 years; p<0.0001). Onset-age ranked: [a] BP-I men (23.0+/-12.8); [b] BP-I women (26.0+/-14.2); [c] BP-II men (29.7+/-19.1); and [d] BP-II women (30.1+/-17.5 years. Juvenile-onset (

There was some variance among sites and only 34.1% of patients were evaluated at onset.

Type I BPD began much earlier than type II; its mainly psychotic presentations occurred earliest, but BP-I men were younger than women, especially at psychotic or mixed onsets.