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A new study has found no evidence of an association between Lyme disease and autism.

"While a proposed link between Lyme disease and autism has garnered considerable attention over the past 2 years, none of the 70 children with autism or 50 unaffected controls in our study had serological evidence of Lyme disease by CDC-recommended two-tier testing," said corresponding author Armin Alaedini, PhD, of Columbia University Medical Center in New York City.

In a research letter in the April 30 issue of the Journal of the American Medical Association, Alaedini and colleagues noted that "among individuals with autism spectrum disorders, rates of seropositivity for Lyme disease of greater than 20% have been reported."

That's potentially dangerous as it suggests that autism can be effectively treated with antibiotics, Alaedini said.

Controlled studies to assess serological evidence of infection with Borrelia burgdorferi -- the causative agent in Lyme disease -- in patients with autism are lacking, so the researchers decided to put that claim to the test.

Serum samples from 120 children ages 2 through 18 were acquired from the Autism Genetic Resource Exchange (37 with autism and 27 unaffected siblings) and the Weill Cornell Autism Research Program (33 with autism, 8 unaffected siblings), and 15 unrelated healthy controls.

Testing for antibodies to B. burgdorferi was performed according to the two-tier algorithm recommended by the Centers for Disease Control and Prevention. Initial screening for anti-B burgdorferi immunoglobulin G and M antibodies was performed with separate enzyme-linked immunosorbent assays (ELISAs).

Specimens classified as borderline or positive were further tested by Western blotting for IgG or IgM antibodies to electrophoresis-separated B. burgdorferi strain B31 proteins.

Of the 70 patients with autism, one was positive by ELISA for anti-B. burgdorferi G, whereas four were borderline by ELISA for IgM.

Of the 50 children in the unaffected control group, 4 were positive and 1 was borderline for IgG by ELISA, whereas 1 was positive by ELISA for IgM.

"In other words, zero children in both groups had serological evidence of Lyme disease by two-tier testing," Alaedini said in an interview.

"A case-control study such as this does not address whether Lyme disease may cause autism-like behavioral deficits in some cases," he said.

"However, the study's sample size is large enough to challenge the idea that 20% or more of children with autism have Lyme disease," Alaedini said.

"And antibiotics should definitely not be given as a treatment to children with autism unless they test positive for an infectious disease that would call for such treatment," he said.

Susan L. Hyman, MD, an expert in autism and professor of pediatrics at the University of Rochester Medical Center in Rochester, N.Y., agreed and noted that reports suggesting high rates of Lyme disease in children with autism "were largely printed in journals like Medical Hypothesis, which publishes novel ideas with or without science to back them up."

"Unnecessary antibiotic treatment is just bad medicine that can contribute to antibiotic resistance and change the gut microflora, for example," Hyman said.

"The authors have taken a nice first pass at showing there is no link between Lyme disease and autism. Now we need further prospective testing to put the issue to rest," she said.

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