Mitochondria are responsible for producing most of the energy the body uses for every day metabolic functions. More attention has recently been focused on a potential link between ASD and dysfunctional mitochondria [see 2008 Autism-Mitochondria Connection]. A study1published in 2009 in the Journal of Child Neurology further examined this link, finding that a subgroup of patients with mitochondria disorders may be at increased risk for autistic regression, especially around periods of fever.
Mitochondria are intimately tuned to the environment in which they reside and are built to respond quickly to fluctuations in the state of that environment. To characterize a relationship between mitochondria disorders and ASD, researchers from Atlanta identified a group of 28 children who had been diagnosed with both ASD and mitochondrial disease. The most common clinical observation in children with both ASD and mitochondria disorder was "hypotonia," or muscles with low tone, followed closely by "fatigue with activity." They also found that approximately 60% (17 of 28) of these children experienced a regressive form of ASD, a rate of regression that is over two times greater than what is observed in ASD in general. Notably, 12 of those 17 regressions occurred in conjunction with having suffered a fever within a two week period of the regression. However, this regression did not appear to be necessarily linked to vaccinations, as two-thirds of the children that regressed with fever had not received vaccination, and of those who did receive a vaccination, none regressed without also having a fever.
Although a small study, this report illuminates potentially useful new commonalities between children with both an ASD and mitochondria disorder, suggesting that children with mitochondrial disease may be at increased risk for autistic regression and that increased risk may be associated with some fever-response pathway. Although this paper did not establish the temporal relationship between fever and autistic regression, fever-induced regression is a well-known feature of metabolic disorders overall, and the study brings another angle to the already intriguing relationship of fever and autism. In 2008 researchers reported2 that some children with ASD actually improve around periods of fever, suggesting that subgroups of ASD exist in which the individuals react differently to fever. In light of this new data, it is clear we need more research into the body's complex cascade of metabolic and immune actions that accompany fever, how those relate to the biology of autism, and the appropriateness of fever management. Finally, by showing that a subgroup of individuals with mitochondria disorders may be at risk for autistic regression, the publication highlights the continued need for enhanced awareness of the clinical signs of mitochondrial dysfunction.