Autism drug aims to balance brain signals

THE first trial of a drug intended to rebalance the brain chemistry of people with autism has helped symptoms in most of the 25 volunteers who tested it - with reductions in irritability and tantrums, and improvements in social skills.

The announcement coincides with news that the US federal government has finalised its financial package for Hannah Poling. In 2008 the government concluded that vaccinations may have resulted in her autism-like symptoms. The family will receive $1.5 million, plus $500,000 annually to cover the costs of caring for her.

Her case, however, is likely to be unique - she has a rare underlying genetic condition affecting her mitochondria, the powerhouses of the cell. This was judged to account for the symptoms she developed after vaccination.

As the debate over vaccination and autism rumbles on in the US, the results from the drug trial of arbaclofen are encouraging. Although doctors sometimes prescribe drugs for autism, they are usually antidepressants and anti-psychotics and aimed at specific symptoms.

Arbaclofen, by contrast, is intended to rebalance brain chemistry, said to be awry in people with autism spectrum disorders. "We are trying to normalise signalling functions within the brain," says Randall Carpenter of Seaside Therapeutics in Cambridge, Massachusetts. The firm is developing arbaclofen as a generic under the name STX209.

Previous studies suggest that people with autism produce too much of the neurotransmitter glutamate in the brain, which ramps up neural activity. They may also make too little gamma- amino butyric acid (GABA), which dampens activity down.

"Too much activation with glutamate makes people with autism very sensitive to loud noises and other, sudden changes in the environment, increasing anxiety and fear," says Carpenter. Arbaclofen normalises this imbalance. "It may stop them being oversensitive".

The firm released a summary of the results last week, but held the raw data back for publication. Carpenter says the results mirror those released earlier this year from a trial of arbaclofen to combat a specific form of autism linked with fragile X syndrome, which causes mental impairment.

"We've observed significant improvement in social interaction across both studies," says Carpenter, adding that a larger trial of up to 150 patients is planned. But Susan Hyman from the University of Rochester Medical Center in New York cautions against over-interpreting such a small study.

As for last week's vaccine settlement, "the payment does not acknowledge a link between autism and vaccines", says Alison Singer, president of the Autism Science Foundation in New York.

According to Salvatore DiMauro of Columbia University in New York, there are only four other cases of Poling's specific mutation worldwide, so the ruling is unlikely to apply to the other 5000 compensation cases.

sumber : www.newscientist.com