Paternal and maternal ages at conception and risk of bipolar affective disorder in their offspring.
BACKGROUND
A consistent association between paternal age and their offspring's risk of schizophrenia has been observed, with no independent association with maternal age. The relationship of paternal and maternal ages with risk of bipolar affective disorders (BPAD) in the offspring is less clear. The present study aimed at testing the hypothesis that paternal age is associated with their offspring's risk of BPAD, whereas maternal age is not.


METHODS
This population-based cohort study was conducted with individuals born in Sweden during 1973-1980 and still resident there at age 16 years. Outcome was first hospital admission with a diagnosis of BPAD. Hazard ratios (HRs) were calculated using Cox's proportional hazard regression.


RESULTS
After adjustment for all potential confounding variables except maternal age, the HR for risk of BPAD for each 10-year increase in paternal age was 1.28 [95% confidence interval (CI) 1.11-1.48], but this fell to 1.20 (95% CI 0.97-1.48) after adjusting for maternal age. A similar result was found for maternal age and risk of BPAD [HR 1.30 (95% CI 1.08-1.56) before adjustment for paternal age, HR 1.12 (95% CI 0.86-1.45) after adjustment]. The HR associated with having either parent aged 30 years or over was 1.26 (95% CI 1.01-1.57) and it was 1.45 (95% CI 1.16-1.81) if both parents were >30 years.


CONCLUSIONS
Unlike schizophrenia, the risk of BPAD seems to be associated with both paternal and maternal ages.
Menezes
P R
PR
Department of Preventive Medicine, University of Sao Paulo, Brazil.
Lewis
G
G
Rasmussen
F
F
Zammit
S
S
Sipos
A
A
Harrison
G L
GL
Tynelius
P
P
Gunnell
D
D
D000328:Adult; D000367:Age Factors; D001714:Bipolar Disorder / Q000453:epidemiology* / Q000235:genetics; D015331:Cohort Studies; D005260:Female; D005306:Fertilization; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006801:Humans; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D010331:Paternal Age; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult