Can infections in childhood trigger the development of neuropsychiatric disease? A study by Köhler-Forsberg et al1 in this issue of JAMA Psychiatry provides strong epidemiologic evidence that severe infections, as well as exposure to antiinfective agents, place children and teenagers at greater risk for developing neuropsychiatric illnesses. By studying Danish medical records from more than 1 million individuals, the team found that the risk of developing mental disorders in children (age 18 years or younger) was increased by more than 80% after a hospitalization for severe infection. Likewise, the use of medications (specifically antibiotics) to treat infections was linked to a 40% greater risk for mental disorders after exposure. For certain mental disorders, including obsessive-compulsive disorder, the risk increase was particularly high, reaching a staggering 8-fold risk increase in teenagers.