Parental age affects risk for bipolar disorder in offspring
MedWire News: Children conceived to parents older than 30 years face an increased risk for developing bipolar disorder, study findings show.
Paternal and maternal age affected risk for bipolar disorder both independently and combined, suggesting that “cumulative genetic mutations,” play a role, say Finn Rasmussen (Karolinska Institute, Stockholm, Sweden) and colleagues.
Advanced paternal age has been associated with several health-related problems, such as low birth weight, breast cancer, congenital malformations, pre-eclampsia, autism, and schizophrenia.
It has been suggested that this association may be due to the increase in sporadic de novo mutations in male germ cells associated with age.
There is increasing evidence that bipolar disorder and schizophrenia share common susceptibility genes, yet few studies have addressed parental age and risk for bipolar disorder.
In the present study the researchers analyzed census data from Sweden on 711,989 individuals born between January 1973 and December 1980. The closing date was set to allow a minimum period of 6 years at risk for a bipolar disorder episode from age 16 to 22 years.
During the follow-up period 493 (0.07%) participants were admitted to hospital with a diagnosis of bipolar disorder (six were siblings), yielding an incidence of 7.7 cases per 100,000 person-years.
After adjusting for a range of clinical and sociodemographic factors including family history of psychosis and death of a parent before the age of 15 years, paternal age was significantly associated with risk for bipolar disorder in children (hazard ratio [HR]=1.20 per 10-year increase).
A similar result was found for maternal age and risk for bipolar disorder (HR=1.12 per 10-year increase).
Having either parent aged 30 years or over was associated with HR for bipolar disorder of 1.26, and with an HR of 1.45 if both parents were aged 30 years or over, compared with having younger parents.
Despite the clear effect of parental age in the study the researchers say their results “need to be balanced against the likely positive effects of the greater financial stability and likely emotional maturity of older parents.”
They add: “Future research disentangling the pathophysiology underlying the observed associations may help to develop more effective interventions for those who suffer from this disorder.”
The research is published in the journal Psychological Medicine.
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By Andrew Czyzewski