The Febrile Effect in Autism Spectrum Disorder: An Investigation of Behavioral Improvements During Episodes of Fever in Chinese Children

Purpose: Some individuals with autism spectrum disorder (ASD) demonstrate marked behavioral improvements during febrile episodes, which is called febrile effect. This study aimed to investigate the prevalence and characteristics of the febrile effect in children with ASD in China. Methods: One hundred fifty-seven patients diagnosed with ASD were recruited to participate in the study; the parents completed a self-compiled questionnaire regarding the febrile effect. Children who reportedly improved with fever (Improve Group) were compared with those who reportedly did not improve (No Improve Group) on the core symptoms and developmental status. Results: Parent reports of 16.56% of children exhibited behavioral improvements during fever. Improvements included reduced problem behaviors, enhanced cognitive or learning abilities, increased social interaction, and decreased stereotypical behaviors. The Improve Group scored higher in Autism Diagnostic Observation Schedule, Second Edition and Social Responsiveness Scale. There were no significant differences in the incidence of infectious diseases during pregnancy among mothers in the 2 groups; however, a marked disparity was observed in the frequency of febrile episodes within the preceding year. The duration of the febrile effect varied, with 76.92% being temporary and 23.08% showing sustained improvements postfever. Children with sustained improvements had more severe social deficits. Conclusion: The febrile effect is observed in a subset of ASD children and may be associated with more severe social deficits. The heterogeneity in the duration of the febrile effect suggests the need for further research to elucidate the underlying mechanisms and potential therapeutic applications.