Childhood Infections Linked With Increased Mental Illness Risk

December 12, 2018

A nationwide study in Denmark suggests a link between infections in childhood and adolescence and increased risk of subsequent mental disorders. Researchers published the findings in JAMA Psychiatry.

“Although the results cannot prove causality, these findings provide evidence for the involvement of infections and the immune system in the etiology of a wide range of mental disorders in children and adolescents,” researchers wrote.

The nationwide register-based cohort study involved more than 1 million people born in Denmark between 1995 and 2012. Researchers looked at treatment for childhood infections as well as mental health diagnoses and treatment.

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Infections requiring hospitalization were associated with an 84% increased risk of a mental disorder diagnosis and a 42% increased risk of psychotropic medication use, according to the study. Less severe infections treated in primary care were linked with a 40% increased risk of a mental health diagnosis and a 22% increased risk of psychotropic drug use. Antibiotics in particular were associated with higher increased risk.

Post-infection risks were highest for schizophrenia spectrum disorders, obsessive-compulsive disorder, personality and behavior disorders, mental retardation, autistic spectrum disorder, attention-deficit/hyperactivity disorder, oppositional defiant disorder and conduct disorder, and tic disorders, researchers reported.

“The temporal correlations between the infection and the mental diagnoses were particularly notable,” said researcher Michael Eriksen Benrós, PhD, of the Psychiatric Centre Copenhagen at Copenhagen University Hospital, Denmark, “as we observed that the risk of a newly occurring mental disorder was increased by 5.66 times in the first 3 months after contact with a hospital due to an infection and were also increased more than twofold within the first year.”

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These findings may “have a consequence for treatment,” Dr. Benrós said, “and the new knowledge can be used in making the diagnosis when new psychiatric symptoms occur in a young person. But first and foremost, it corroborates our increasing understanding of how closely the body and brain are connected.”

—Jolynn Tumolo


Köhler-Forsberg O, Petersen L, Gasse C, et al. A nationwide study in Denmark of the association between treated infections and the subsequent risk of treated mental disorders in children and adolescents. JAMA Psychiatry. 2018 December 5;[Epub ahead of print].

Bang Rasmussen A. Infections in children tied to subsequent mental illness risk in new study [press release]. Aarhus, Denmark: Aarhus University; December 8, 2018.