Age at onset in bipolar I affective disorder: further evidence for three subgroups.
OBJECTIVE
Preliminary data suggested that there are three subgroups of bipolar affective disorder based on age at onset. The authors sought to replicate those findings and determine the cut-off age of each subgroup.


METHODS
Admixture analysis was used to determine the best-fitting model for the observed ages at onset of 368 consecutively admitted patients. The results obtained were compared with those of the previously described model. The authors also investigated whether affected siblings are more likely to belong to the same theoretical age-at-onset subgroup as identified by admixture analysis.


RESULTS
The existence of three subgroups defined by age at onset was confirmed. The mean ages estimated in this model were 17.4 years (SD=2.3), 25.1 years (SD=6.2), and 40.4 years (SD=11.3). Affected siblings were more likely to belong to the same theoretical subgroup.


CONCLUSIONS
There are three age-at-onset subgroups of bipolar patients, and specific familial vulnerability factors might underlie each subgroup.
Department of Psychiatry, Hôpital Henri Mondor et Albert Chenevier, Assistance Publique-Hôpitaux de Paris, 51 Avenue du Mal de Lattre de Tassigny, 94010 Créteil Cedex, France. bellivier@im3.inserm.fr
Frank
F
Bellivier
Jean-Louis
JL
Golmard
Marcella
M
Rietschel
Thomas G
TG
Schulze
Alain
A
Malafosse
Martin
M
Preisig
Patrick
P
McKeon
Lesley
L
Mynett-Johnson
Chantal
C
Henry
Marion
M
Leboyer
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D001714:Bipolar Disorder / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D011336:Probability; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D035781:Siblings / Q000523:psychology