Washington, Dec 9 :
US researchers have created what might be an accurate model of autism not associated with a broader neuropsychiatric syndrome, which includes conditions like - Fragile X, the most common cause of inherited mental impairment, and Rett Syndrome, a childhood neurodevelopmental disorder characterized by normal early development followed by slowed brain and head growth, seizures, and mental retardation.
Autism is a neuropsychiatric disorder characterized by repetitive behaviours and by impairment in social interactions and communication skills.
The animal -model finding was based on a study, led by Thomas Sudhof, M.D., professor and chairman of neuroscience at UT Southwestern, which might help researchers better understand abnormal brain function in autistic humans, which could help them identify and improve treatment strategies.
"Prior to this study we knew next to nothing about the mechanisms of autism in the brain," said Craig M. Powell, M.D., Ph.D., assistant professor of neurology and psychiatry at the University of Texas Southwesters Medical Centre at Dallas and a co-researcher in the study.
"With this research, we can study changes in the brain that lead to autistic behaviours and symptoms, which may help us understand more about progression and treatment of the disorder," Powell added.
The research team replaced the normal mouse neurologin-3 gene with a mutated neuroligin-3 gene associated with autism in humans.
By doing so, the researchers were able to create a gene in the mice that was similar to the human autism disease gene.
While the result amounted to a very small change in their genetic makeup, it perfectly mimicked the same small change occurring in some patients with human autism.
Dr. Powell studied the genetically altered mice and found that, when examined in behavioural tests that might reflect key signs of autism, they showed decreased social interaction with other mice; other traits, such as anxiety, coordination and pain sensitivity, were unaffected.
Powell said that these social interaction deficits were hallmark features of human autism. In addition, the mice showed enhanced spatial learning abilities, which might resemble the enhanced cognitive abilities in autistic savants, people who have a severe developmental or mental handicap as well as extraordinary mental abilities.
"These findings could be especially helpful in identifying novel treatment approaches. We already know that inhibitory chemical synaptic transmission from one neuron to the next is increased in this mouse model. Now we can test drugs that decrease this effect directly in the mice and ask whether this reverses their social interaction deficits," Powell said.
The research was presented at the American College of Neuropsychopharmacology annual meeting.