Childhood exposure to nitrogen dioxide (NO2), a key component of air pollution and smog, appears to raise the risk schizophrenia, independent of genetic liability, results of a large population-based study show.
"In our study, a polygenic risk score for schizophrenia, based on common variants related to schizophrenia, could not account for the association between childhood NO2 exposure and schizophrenia," first author Henriette Thisted Horsdal, PhD, Aarhus University in Denmark, told Medscape Medical News.
The study was published online November 1 in JAMA Network Open.
Genetics, Environment, or Both?
Schizophrenia is highly heritable. Recent studies have suggested that exposure to NO2 during childhood raises the risk of schizophrenia later in life. Whether the increased risk associated with NO2 exposure is owing to a greater genetic liability among those exposed to highest NO2 levels is unclear.
To investigate, Horsdal and colleagues used interlinked data from multiple longitudinal, population-based registries with information on both residential exposure to NO2 and genetic profiles.
The cohort included 23,355 people (51% male) born in Denmark between May 1981 and December 2002, who were followed up from age 10 until the first occurrence of schizophrenia, immigration, death, or the end of 2012, whichever came first.
