The architecture of the autistic brain is speckled with patches of abnormal neurons, according to research partially funded by the National Institute of Mental Health (NIMH), part of the National Institutes of Health. Recently published in the New England Journal of Medicine, the study suggests that brain irregularities in children with autism can be traced back to prenatal development .
According to an article in the Morbidity and Mortality Weekly Report, a publication of the U.S. Centers for Disease Control and Prevention (CDC), the prevalence of autism spectrum disorder (ASD) is higher than ever . The CDC periodically surveys the prevalence of ASD, looking during each surveillance period at the percentage of 8-year-old children who have current ASD diagnoses. In 2000, a survey of children born in 1992 revealed that one in 150 had ASD. These numbers have been steadily climbing, such that the most recent survey — completed in 2008 and surveying children born in 2000 — indicates that one in 88 children has ASD. The numbers are even more disturbing for male children, who have an ASD prevalence of one in 54.
While the alleged link between vaccines — particularly the measles, mumps, and rubella (MMR) vaccine — and autism has been thoroughly discredited in more than 20 well-conducted studies of vaccine side effects , fears about the side effects of vaccination nevertheless remain a major factor influencing the healthcare decisions some parents make. This has led to an increasing percentage of unvaccinated children in the U.S. in recent years, which in turn has ramifications for public health.
A recent study published in the Journal of the American Medical Association, however, sheds new light on physiological roots — though not causes — of autism , and in so doing rules out the potential for any link between vaccination and development of the disease. In the study, researchers examined the size and number of neurons in the prefrontal cortex of young deceased males with autism, and compared the data to that obtained from young deceased non-autistic males.
The largest and most rigorous twin study of its kind to date has found that shared environment influences susceptibility to autism more than previously thought.
The study, supported by the National Institutes of Health, found that shared environmental factors — experiences and exposures common to both twin individuals — accounted for 55% of strict autism and 58% of more broadly defined autism spectrum disorders (ASD). Genetic heritability accounted for 37% of autism and 38% of ASD. Random environmental factors not shared among twins play a much smaller role.