Table 3.

Details of the studies investigating cohort effects on age‐at‐onset distributions in bipolar disorder.

Study	N	Country	Diagnosis	Recruitment	Definition of age at onset	Method of determining AAO	Mean age of sample at study entry (SD)	Cohort	Early onset	Mid‐onset	Late onset
									Mean (SD), %	Mean (SD), %	Mean (SD), %
Bauer et al. (2015)	4037	23 countries across Asia, Africa, Australia, Europe, North and South America	DSMI‐IV BPI	Data obtained retrospectively from 36 collection sites for a study of the impact of solar insolation on the age of onset of bipolar disorder	Age at first episode of depression, mania or hypomania meeting DSM‐IV criteria (according to medical case notes and interviews).	Medical records and semi‐structured interviews	48.1 (14.5)	Whole sample without birth cohorts (n = 4037) With birth cohorts incl. in model (n = 4037): born <1940, 1940‐1959, >1959 Youngest cohort, born >1959 (n = 2550)	17.2 (3.2), 41.7% 20.7 (5.8), 62.1% 18.1 (3.7), 56.9%	23.9 (5.1), 24.7% N/A N/A	32.20 (12.0), 33.6% 30.1 (10.4), 37.9% 25.8 (8.4), 43.1%
Golmard et al. (2016)	3896	Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, The Netherlands, Norway, Portugal, Spain, Switzerland and the UK	DSM‐IV or ICD−10 BPI	Inpatients and outpatients recruited for participation in genetic studies, and patients recruited for the EMBLEM study, a multicentre study conducted in 14 different European countries between 1993 and 2008	Age at which DSM‐IV criteria for an affective episode was first met (according to medial case notes and interviews)	Medical records. And semi‐structured clinical interviews	44.0 (13.3)	Whole sample born >1960 Whole sample born ≤1960 Matched for age at interview (n = 125): Born >1960 Born ≤1960	20.6 (3.7), 65% 19.3 (3.0), 49.7% 18.2 (2.5), 48% 16.9 (0.9), 16%	26.8 (1.7), 26% 25.9 (1.8), 32.8%	29.8 (0.5), 9% 29.8 (0.5), 17.6% 30.9 (5.3), 52% 27.1 (6.9), 84%