Parental asthma may be associated with increased risk for bipolar disorder and schizophrenia spectrum disorders in offspring, according to the results published online in Schizophrenia Bulletin. While the results of the study do not suggest a direct link between asthma and mental illness, the researchers note a potential shared genetic vulnerability.
The study included all children born in Sweden from 1973 to 1995 (N>2 million). The researchers assessed associations between childhood hospitalization for asthma, parental asthma during and pre-pregnancy, and subsequent bipolar and schizophrenia spectrum disorders.
The researchers found that children who had been hospitalized for asthma between age 11 and 15 had increased rates of bipolar (adjusted hazard ratio [aHR], 1.73; 95% CI, 1.21–2.47) and schizophrenia spectrum disorders (aHR, 1.62; 95% CI, 1.08-2.42). However, children with hospitalizations for asthma before age 11 did not have these increased rates.
The researchers also found an association between both maternal and paternal asthma and bipolar disorder (aHR, 1.60; 95% CI, 1.27-2.02, and aHR, 1.44; 95% CI, 1.08-1.93, respectively). However, they did not find any associations between parental asthma schizophrenia spectrum disorders.
“This study strengthens the evidence that severe asthma during adolescence increases the risk of [severe mental illness],” the study investigators concluded.
Wu Q, Dalman C, Karlsson H, et al. Childhood and parental asthma, future risk of bipolar disorder and schizophrenia spectrum disorders: a population-based cohort study [published online March 9, 2018]. Schizophr Bull. doi:10.1093/schbul/sby023