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Genetic Marker Has Been Found
"Our research suggests one way we might predict which individuals are at risk of being aggressive and destructive and provide treatment before problems occur," Craig Kennedy, professor of special education at Vanderbilt University's Peabody College of education and human development, said.
Fifteen to 20 percent of adults with developmental/intellectual disabilities have problem behaviors. For this study, the researchers focused specifically on aggression, self-injury or property destruction and set out to determine if there was a genetic underpinning for these behaviors. They focused on the gene that encodes monoamine oxidize A or MAOA. MAOA is involved in the regulation of the neurotransmitter serotonin, which is linked to appetite and mood, and the neurotransmitter and hormone norepinephrine, which is linked to the fight-or-flight response. Previous studies found that variations in MAOA were linked to violent behavior.
The researchers studied 105 white men between the ages of 18 and 50. The individuals were divided into three groups: those with developmental/intellectual disabilities and a history of more than 10 years of problem behavior, those with the disabilities but without problem behavior, and a typically developing control group. Only white men were sampled because the MAOA gene is linked to the X chromosome and also is shown to vary by ethnicity.
Forty-three percent of those with developmental/intellectual disabilities and behavior problems had the gene variant, compared to 20 percent of the same group with no behavior issues and 20 percent of a typically developing control group.
The same MAOA variation has also been linked to autism in children, autism severity and communication problems. The researchers suggest that problem behaviors linked to this variation may explain increased autism severity in individuals with it.
MEDICA.de; Source: Vanderbilt University