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Using admixture analysis to examine birth‐cohort effects on age at onset of bipolar disorder
Author(s) -
Golmard J.L.,
Scott J.,
Etain B.,
Preisig M.,
Aubry J.M.,
Henry C.,
Jamain S.,
Azorin J.M.,
Leboyer M.,
Bellivier F.
Publication year - 2016
Publication title -
acta psychiatrica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.849
H-Index - 146
eISSN - 1600-0447
pISSN - 0001-690X
DOI - 10.1111/acps.12478
Subject(s) - bipolar disorder , cohort , age of onset , psychology , psychiatry , medicine , pediatrics , cohort study , demography , clinical psychology , cognition , disease , sociology
Objective It is suggested that age at onset ( AAO ) of bipolar I disorder ( BP ‐I) is decreasing. We tested for a birth‐cohort effect on AAO using admixture analysis. Method A clinical sample of 3896 BP ‐I cases was analysed using two approaches: (i) in a subsample with untruncated AAO × birth year distribution ( n = 1865), we compared the best‐fitting model for the observed AAO in patients born ≤1960 and >1960, (ii) to control for potential confounders, two separate subsamples born ≤1960 and >1960 were matched for age at interview ( n = 250), and a further admixture analysis was undertaken. Results The two approaches indicated that the proportion of cases in the early AAO category was significantly greater in cases born >1960; manic onsets were also more frequent in the early onset BP ‐I cases born >1960. Conclusion The decrease in AAO of BP ‐I in recent birth‐cohorts appears to be associated with an increase in the proportion of cases in the early onset subgroup; not with a decrease in the mean AAO in each putative subgroup. This could indicate temporal changes in exposure to risk factors for mania.