Autistic symptoms following herpes encephalitis.

Autism is a childhood onset neurodevelopmental disorder characterized by reciprocal social deficits, communication impairment, and rigid ritualistic interests, with the onset almost always before three years of age. Although the etiology of the disorder is strongly influenced by genes, environmental factors are also important. In this context, several reports have described its association with known medical conditions, including infections affecting the central nervous system. In this report, we describe an 11-year-old Asian youngster who developed the symptoms of autism following an episode of herpes encephalitis. In contrast to previous similar reports, imaging studies suggested a predominant involvement of the frontal lobes. At follow-up after three years, he continued to show the core deficits of autism. This case further supports the role of environmental factors, such as infections, in the etiology of autism, and suggests that in a minority of cases, autistic symptoms can develop in later childhood.