One of the theories posited about autism causation is that childhood infections can result in autism. A recent study from the Arhus, Denmark, explores this by checking how often children are admitted to the hospital for infectious diseases. Given that maternal infections do appear to be associated with a greater risk of autism, the idea of childhood infections is worth considering. I would add that the attention to mitochondrial disorders and autism that was high in the past couple of years would also suggest this is a valuable area to consider.
OBJECTIVE: To investigate the association between hospitalization for infection in the perinatal/neonatal period or childhood and the diagnosis of autism spectrum disorders (ASDs). DESIGN: A population-based cohort study. SETTING: Denmark. PARTICIPANTS: All children born in Denmark from January 1, 1980, through December 31, 2002, comprising a total of 1 418 152 children. EXPOSURE: Infection requiring hospitalization. MAIN OUTCOME MEASURE: The adjusted hazard ratio (HR) for ASDs among children hospitalized for infection compared with other children. RESULTS: A total of 7379 children were diagnosed as having ASDs. Children admitted to the hospital for any infectious disease displayed an increased rate of ASD diagnoses (HR, 1.38 [95% confidence interval, 1.31-1.45]). This association was found to be similar for infectious diseases of bacterial and viral origin. Furthermore, children admitted to the hospital for noninfectious disease also displayed an increased rate of ASD diagnoses (HR, 1.76 [95% confidence interval, 1.68-1.86]), and admissions for infection increased the rate of mental retardation (2.18 [2.06-2.31]). CONCLUSIONS: The association between hospitalization for infection and ASDs observed in this study does not suggest causality because a general association is observed across different infection groups. Also, the association is not specific for infection or for ASDs. We discuss a number of noncausal explanatory models.
Autistic children are admitted to the hospital for infectious diseases more often than the rest of the population. But, in general autistic children are admitted to the hospital more often than the rest of the population.
Bloomberg Businessweek discussed this paper in No Link Between Childhood Infections, Autism. They interviewed Dr. Andrew Zimmerman of the Kennedy Krieger Institute. Dr. Zimmerman concurred with the conclusions of the paper:
"Yes, there is an increased rate of hospitalization preceding the diagnosis of autism, but it doesn’t support a causal relationship between autism and infections,” Zimmerman said.
This is significant, in my view. Dr. Zimmerman is one of the doctors who treated Hannah Poling (the young girl whose case was conceded by the Department of Health and Human Resources in the vaccine court, sparking the public interest in the subject).
It is also worth noting that the study considered specific infections. From the Bloomberg/Newsweek story:
And the researchers could point to no particular infection that upped the risk.
They therefore conclude that childhood infections cannot be considered a cause of autism.
“We find the same relationship between hospitalization due to many different infections and autism,” noted lead study author Dr. Hjordis Osk Atladottir, of the departments of epidemiology and biostatistics at the Institute of Public Health, University of Aarhus in Denmark. “If there were a causal relationship, it should be present for specific infections and not provide such an overall pattern of association.”