The incidence of three childhood neuropsychiatric disorders, including autism, increased among Danish children between 1990 and 2004, according to a report in the February issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals. The findings suggest that recent upward trends in reported autism diagnoses may be part of a broader pattern in childhood mental illness.

Autism is characterized by social and language abnormalities and repetitive patterns of behavior, according to background information in the article. "A public health debate surrounding the prevalence of autism has become a prominent feature in both the public and professional autism literature in the United States and abroad," the authors write. "The debate is fueled by numerous studies reporting marked increases in recent years in the prevalence of autism or its proxy measure, the prevalence of individuals receiving autism services."

Hjördís Ósk Atladóttir, MB, University of Aarhus, Denmark, and colleagues examined trends in four childhood neuropsychiatric disorders among all 669,995 children born in Denmark between 1990 and 1999. The conditions were autism spectrum disorder, which comprises autism and milder developmental disorders; hyperkinetic disorder, marked by hyperactivity and a tendency to move from one activity to the next without completing any one; Tourette syndrome, characterized by uncontrollable vocal or motor behaviors known as tics; and obsessive-compulsive disorder, in which an individual experiences recurrent obsessive thoughts or performs compulsive acts. Denmark provides free, universal health care coverage, and all psychiatric diagnoses treatments are recorded in a national registry.

Through 2004, a total of 4,376 children were given 4,637 diagnoses for these disorders. The incidence of hyperkinetic disorder, Tourette syndrome and autism spectrum disorders all increased significantly over time, while obsessive-compulsive disorder did not. "It is difficult to explain why obsessive-compulsive disorder was the only disorder displaying another pattern; the reason may be etiologic, due to nonetiologic diagnostic differences or due to the relatively short follow-up," the authors write.

"Although the reasons for the observed common pattern of change in reported cumulative incidence in Tourette syndrome, hyperkinetic disorder and autism spectrum disorder cannot be address with these data, it is clear that the number of children with neuropsychiatric disorders and their families in need of support and services has been growing in recent years," the authors conclude. "Furthermore, while the search for causes should proceed unabated, the ultimate value of these data are their contribution to the growing awareness of child neurodevelopment problems in general and understanding of the resources needed to ensure optimal development for all children."

Source: JAMA and Archives Journals