Researchers have found a drug that can help patients with Fragile X syndrome, the most common cause of inherited intellectual impairment (formerly known as mental retardation), stay calm in social situations by treating their anxiety.

Dr. Elizabeth Berry-Kravis and her team found that a drug called Arbaclofen reduced social avoidance and repetitive behavior in Fragile X patients, especially those with autism, by treating their anxiety. The drug increases GABA, a chemical in the brain that regulates the excitatory system in Fragile X patients, who have been known to have too little GABA to do the job otherwise, causing their excitatory systems to “signal out of control” and make them anxious.

Such patients have been known to cover their ears or run away at their own birthdays because they are overwhelmed by the attention, but one trial participant said he was able to enjoy his birthday party for the first time in his life while he was on Arbaclofen, she said.

“I feel like it’s kind of the beginning of chemotherapy when people first realized you could use chemotherapy to treat cancer patients instead of just letting them die,” said Berry-Kravis, a professor of neurology and biochemistry at Rush University Medical Center in Chicago who has studied Fragile X for more than 20 years.

She said people used to think Fragile X patients couldn’t be helped either, but she and her team have proven that by using knowledge from existing brain mechanism studies, doctors can select medications to target specific problems in Fragile X patients’ brains.

Fragile X syndrome is a change in the FMRI gene, which makes a protein necessary for brain growth, and studies indicate it causes autism in up to one-third of patients diagnosed with it. Unlike Fragile X syndrome, which is genetic, autism is a behavioral diagnosis characterized by an inability to relate to other people or read social cues. Autism and Fragile X are linked, but not mutually exclusive. A core symptom of both is social withdrawal.

Sixty-three patients with Fragile X participated in Berry-Kravis’s placebo-controlled, double-blind clinical trial from December 2008 through March 2010. Of those, the patients with autism showed the biggest improvements in social behavior, Berry-Kravis said.

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