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“As far as we are aware, this is the first study to find increased risk of bipolar disorder in children of individuals with asthma,” wrote Joseph Hayes, M.D., of University College London and colleagues. “Asthma admissions before aged 11 do not appear to be linked to bipolar or schizophrenia spectrum disorders.”
Hayes and colleagues collected data from Swedish registers from 1973 through 2011. These registers contain sociodemographic and medical information on each resident of Sweden, and parents can be linked to children via a unique identifier. The researchers included all children born in Sweden from 1973 to 1995 and their parents in the study cohort.
Children were grouped according to the age of first inpatient admission for asthma: at 5 years of age or younger, 6 to 10 years of age, and 11 to 15 years of age. Hospital admissions of the mothers and fathers for asthma prior to the birth of the children were also recorded.
Of the more than 2 million individuals born in Sweden between 1973 and 1995, 40,187 (1.78%) children were admitted with asthma before the age of 15, and 9,892 (0.44%) children were born to mothers who were hospitalized for asthma before their birth.
Following adjustment for confounding factors, the researchers found that there was an association between asthma admission between age 11 and 15 and both bipolar disorder (hazard ratio [HR] = 1.73) and schizophrenia spectrum disorder (HR = 1.62). There was no association between asthma and bipolar disorder and schizophrenia in children who were admitted for asthma before age 11. Additional analysis also revealed an association between both maternal and paternal asthma and bipolar disorder, but not between parental asthma and schizophrenia spectrum disorders.
“Taken together, our results do not suggest a straightforward link between asthma and severe mental illness via neurodevelopmental effects of inflammation, but potentially there is shared genetic vulnerability,” the authors wrote. “This finding has implications for understanding the differential pathogenic mechanisms of bipolar and schizophrenia spectrum disorders.”
For related information, see the Psychiatric News article “When Should Psychiatrists Manage [Other] Medical Conditions.”
(Image: iStock/catinsyrup)
