Study Watch : Abnormalities of Cholesterol Metabolism in Autism Spectrum Disorders

In the September 2006 issue of American Journal of Medical Genetics there was a study concerning cholesterol and autism -

Abnormalities of Cholesterol Metabolism in Autism Spectrum Disorders

The text of the study is now freely available from pubmed central so go read it if you are interested.

The researchers in this study were investigating whether Smith-Lemli-Optiz Symdrome (SLOS) is more common among individual with autism than in the general population. SLOS, as I have written about before, is a generic disorder where the body is unable to produce enough cholesterol which causes a wide variety of problems, including autism. Earlier research had demonstrated that autism is very common in individuals with autism so the researchers were looking into whether SLOS was a common cause of autism.

The study selected 100 samples from children contained in the Autism Genetic Resource Exchange (AGRE). These children were from families with 2 or more children with non-regressive autism. Blood samples for each of the participants were analyzed for cholesterol level and all cholesterol precursors.

None of the samples had indications that the individuals had SLOS.

However, 19 of the 100 individuals had total cholesterol levels less than 100 mg/dL, which is very low. There were also indications that the lower level of cholesterol in this subset was due to problems with the body's process of making cholesterol rather than a lack of dietary sources.

To put this cholesterol level in perspective, the normal average total level should be in the range from about 160-200, depending on age, sex, and other factors. If you look at data published by the CDC that is referenced by this study this level is in the bottom 5th percentile for children (ie over 95% of children have a higher level with the average level being 60% higher).

The study concluded that although autism is very common in individuals with SLOS that SLOS is not a common cause of autism. But, and this is the interesting part for me, the finding that about 20% of the sample had a very low cholesterol was not expected and the researchers suggest that further research is needed.