Autism Research Review – June 2013

CC BY-SA by Egan Snow

CC BY-SA by Egan Snow

Protein causing Autism linked to specific behaviours

Nature Neuroscience published a study led by Dr. Carlos Portera-Cailliau on June 3rd. Using mice model in a laboratory, the team lead by Dr. Carlos found that mice that lacker fmr1 gene, showed some of the same symptoms of the Fragile X Syndrome like impaired social interaction and learning skills.

The Fragile X syndrome is the commonest cause of autism. The syndrome damages the synapses between neurons leading to abnormal behaviours. The fmr1 gene is important for production of the fmr protein which in turn is crucial to the formation of synapses. The research found that mice lacking the gene showed autism-like behaviours. Also, mice lacking the gene had neurons that fired too much, too often and synchronously. This excessive excitability might be the reason for the symptoms of fragile X syndrome and thereby autism. The excessive firing leads to seizures which are common in FXS and hyper-responsiveness to simple sensory stimulation that is common to autism.

Strategies to reduce the neuronal excitability might be thought of as therapy for FXS and autism.

Reduced tryptophan metabolism might become diagnostic test for autism

A study published this month in the Molecular Autism has raised hope of a simple blood test to predict autism. The research published by Dr. Boccuto showed that the metabolism of the amino acid L-tryptophan was significantly reduced in individuals with autism as compared to other typical children and individuals suffering from other neurological disorders.

The genes that bring about tryptophan metabolism were also found to be inadequately expressed in individuals with autism. Only once the exact fault in the tryptophan metabolism is clear that it can be used as a blood test to diagnose autism which is a purely clinical diagnosis currently. As early intervention is the only way to salvage a child with autism, the test could help numerous children from leading a life of solitude and dependency.

L-tryptophan is already known to be important in the process of production of neurotransmitters like melatonin, serotonin, which are already linked to neurological and behavioural disorders.

Failure to trigger reward centres in brain in autism cause of social deficit, study says

A new paper published by scientists at the Stanford University School of Medicine under the leadership of Daniel Abrams, suggests a possible cause of the lack of social skills in children with autism. The research found that regions of the brain that are programmed to respond to human voices have poor connectivity with the reward- processing parts of the brain in autism.

The deficient voice-reward connectivity prevents the children from recognising speech as a pleasant experience which visibly makes them averse to grasp as well as produce speech. The paper published in the Proceedings of the National Academy of Sciences was the first to show the disruption of the reward circuits in the autistic brain.

MRI scans were used to assess the degree of stimulation of reward area on stimulation with human voices. The higher the degree of social aversion, the lesser the stimulation of reward centres. The research also proved why autistic individuals are less interested in human voices. Future studies could focus on improvement of the voice-reward circuitry post-interventions to assess their utility in treating autism.