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Autistic brains lack differentiation

By Gracie Valena - 29 May 2011 17:50:1 GMT
Autistic brains lack differentiation

Genes in the brains of autistic persons encode information differently from healthy brains, researchers from UCLA have found.

Autism has many causes, so the scientists, led by Dr. Daniel Geschwind, the Gordon and Virginia MacDonald Distinguished Chair in Human Genetics and a professor of neurology and psychiatry at the David Geffen School of Medicine at UCLA, did not expect to find similar gene expression patterns among autistic brains. But looking at brain tissue samples taken from the brains of autism patients who had passed away, they found that the autistic brains shared a lack of differentiation.

The cerebral cortex of the brain has a frontal lobe that is involved in judgment, creativity, emotions and speech; and temporal lobes that control hearing, language and processing of sounds. Geschwind explained that ''In a healthy brain, hundreds of genes behave differently from region to region, and the frontal and temporal lobes are easy to tell apart.'' However, Geschwind reported, said. ''We didn't see this in the autistic brain. Instead, the frontal lobe closely resembles the temporal lobe. Most of the features that normally distinguish the two regions had disappeared.''

The researchers also found that the autistic brains had less of the genes that are involved in neuron function and communication; and the autistic brains had a markedly higher level of the genes used for immune functions and inflammatory responses.

Geschwind highlighted the importance of the research findings: ''By demonstrating that this pathology is passed from the genes to the RNA to the cellular proteins, we provide evidence that the common molecular changes in neuron function and communication are a cause, not an effect, of the disease.''

The researchers said that the next step will be to look into the other parts of the brain for genetic and other causes of autism. The study by Geschwind, Irina Voineagu, et al., was published May 25 in the advance online edition of Nature.

Treatment update

While advances in understanding the causes of autism hold high hopes for preventing autism in the future, millions of families worldwide are dealing with the condition every day.

Autism (or autism spectrum disorder, ASD) is often treated with antiseizure medications because quite often people with ASD also have seizures, epilepsy and abnormal electroencephalograms. But there isn't much information about how well these treatments work.

To get some insight into the effectiveness of seizure treatments for children with ASD, Dr. Richard E. Frye from the University of Texas in Houston and Dr. James B. Adams from the Arizona State University in Tempe developed a comprehensive on-line seizure survey.

Respondents - 733 parents of children with ASD and 290 control parents - reported that ''in general, antiepileptic drugs (AEDs) were perceived to improve seizures but worsened other clinical factors for children with clinical seizure.'' Other clinical factors included sleep, communication, behavior, attention and mood.

Valproic acid, lamotrigine, levetiracetam and ethosuximide emerged as the most effective in improving seizures and causing the least side effects. Also, the ketogenic diet was reported as seen to improve both seizures and other clinical factors.

The researchers say that the study, although limited to the perception of parents, could help parents choose seizure treatments.

The study was published in the 18 May 2011 issue of BMC Pediatrics.