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Fever Plus Mitochondrial Disease Could Be Risk Factors for Autistic Regression

Posted Sep 24 2009 10:11pm

Autism, regression, mitochondrial disease and vaccines. With a combination like that, this paper is likely going to be very important.

Fever Plus Mitochondrial Disease Could Be Risk Factors for Autistic Regression

Here is the abstract:

Autistic spectrum disorders encompass etiologically heterogeneous persons, with many genetic causes. A subgroup of these individuals has mitochondrial disease. Because a variety of metabolic disorders, including mitochondrial disease show regression with fever, a retrospective chart review was performed and identified 28 patients who met diagnostic criteria for autistic spectrum disorders and mitochondrial disease. Autistic regression occurred in 60.7% (17 of 28), a statistically significant increase over the general autistic spectrum disorder population (P < .0001). Of the 17 individuals with autistic regression, 70.6% (12 of 17) regressed with fever and 29.4% (5 of 17) regressed without identifiable linkage to fever or vaccinations. None showed regression with vaccination unless a febrile response was present. Although the study is small, a subgroup of patients with mitochondrial disease may be at risk of autistic regression with fever. Although recommended vaccinations schedules are appropriate in mitochondrial disease, fever management appears important for decreasing regression risk.

The authors note neurologic regression in general (not just autistic regression) is observed with patients who have metabolic diseases:

Patients with mitochondrial diseases, like many patients with metabolic diseases, are at increased risk of neurologic regression in conjunction with stressors such as fever, infection, and dehydration.

They studied 28 patients who met DSM -IV criteria for autism and diagnostic criteria for mitochondrial disease.

They define regression and whether it is related to fever thusly:

Autistic regression was defined as loss of developmental skills that included speech, receptive skills, eye contact, and social interests in individuals <3 years of age. A relationship between fever and autistic regression is defined as regression beginning within 2 weeks of a febrile episode without the suggestion of infectious meningitis or encephalitis.

One comment—the definition of regression is somewhat vague to me. What is also critically important in this discussion is whether there were any signs of autism before the regression. Or, as some may put it, is this regression into autism or autistics undergoing regression? Is there a mix of pathways?

They state that 17 of the 28 patients studied underwent an autistic regression. This is higher than the roughly 25% value for autistic regression they assumed for the general autism population, and statistically significant.

In other words, they are saying that autistic regression may occur more often with kids with mitochondrial diseases.

They note that some of the fevers could be linked to vaccination:

The 17 individuals with autistic regression could be divided into 2 groups, those who regressed with fever (70.6%, 12 of 17) and those who regressed without identifiable linkage to fever or vaccinations (29.4%, 5 of 17).


No individual showed regression with vaccination unless a febrile response was present.

They discuss the concerns with vaccination in the conclusion, noting that vaccination is still recommended for children with mitochondrial diseases. My experience in discussing this issue with mitochondrial disease experts is that they find vaccination to be extremely important. If, for some reason, they decide to not vaccinate a child with mitochondrial disease, they insure that all family members are vaccinated to protect the child.

Children with identified mitochondrial diseases are routinely managed carefully by their physicians with aggressive fever control and hydration. In this context, vaccination of children with mitochondrial diseases is recommended. In our experience, the vast majority of patients with mitochondrial diseases receives a full vaccination schedule according to American Academy of Pediatric guidelines without consequences, particularly when physicians are sensitive to fever control and hydration. In our patients with mitochondrial disease and autistic spectrum disorders, the vaccines did not appear related to the neurologic regression.

I will note again that I feel autistic regression as defined is too vague. Were the patients on the spectrum before the regression? Were they typically developing before the regression?

At least two children were noted to have multiple regressions (a sibling pair). That indicates that at least in some cases, regressions occurred in people already autistic. There just isn’t other information on this.

Another area I would like to see discussed further is on siblings:

Affected siblings were identified in 35.7% (10 of 28).

Affected how? Mitochondrial disease. But, are they also autistic? It would seem not since they included one sibling pair.

This is a big question to me. While the spotlight has been shown on the possibility of mitochondrial disorders being linked to autistic regression, the more general question is more important: could fevers induced by vaccination result in any regression (autistic or otherwise) in people with mitochondrial disorders.

Another question in my mind in this study. Are there patients who underwent regression from non-autistic to autistic) after age 3? According to the John’s Hopkins group, this doesn’t happen. According to them, there is an age window where the regressions could result in autism. This is a very important question in how these patients might fit in to the broader spectrum of autism.

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