Early signs of autism can be detected in the brains of four-month-old infants using an advanced scanning technique, research has shown.
Currently the condition cannot be diagnosed until after the age of two, by observing a child’s behaviour.
The new discovery is likely to improve scientists’ understanding of autism, and may help families in the future, experts believe.
Researchers used near-infrared spectroscopy (NIRS) to study the brain activity of two groups of infants, one of which had older brothers or sisters with autism.
The technique relies on the way more or less active parts of the brain absorb long-wavelength light differently.
Probes attached to the skin surface fire beams of light which are able to pass through the skull. After scattering through the brain, they are picked up by receptors to provide a measure of brain activity.
The babies were tested as they watched videos of socially interesting human actions, such as peek-a-boo or incy-wincy spider. Scans were also carried out while the infants listened to vocal sounds such as laughter and yawning, or non-human sounds such as running water and toys rattling.
Autism is a wide-ranging brain condition that affects a person’s ability to communicate and socialise. An estimated 600,000 children and adults in the UK suffer from autism, which is four times more likely to affect boys than girls.
There is strong evidence that autism runs in families. In the study, at-risk babies with a family history of the condition showed unusual brain responses to social stimuli not shared by non-at-risk babies.
Lead researcher Dr Sarah Lloyd-Fox, from Birkbeck, University of London, said: “We still know very little about the earliest appearing symptoms and warning signs of autism. Our findings demonstrate for the first time that direct measures of brain functioning during the first six months of life may help further our understanding of the development of autism.
” At this age, no behavioural markers of autism are yet evident, and so measurements of brain function may be a more sensitive indicator of risk.
“The earlier that we can measure infants’ responses, the clearer an idea we can develop of how genes and the environment might be interacting, and this will help us to develop interventions which could support typical brain development.
“It is important to note, however, that individual babies did not all show the same pattern of brain responses. It is paramount that we revisit these findings when the babies are over two years of age and can be assessed for a diagnosis of autism.”
The findings are reported in the latest issue of the journal Proceedings Of The Royal Society B.
Bev Dancer, whose son Martin took part in the study, said: “It is difficult raising a child with social and communication difficulties and, without an early diagnosis, many mothers blame themselves. Understanding how the brain works during these early years would help many families guide their child and have an enormous impact on their child’s development.”
Christine Swabey, chief executive of the charity Autistica, which part-funded the research, said: ” These are the very earliest neurological differences to be found in children at risk of later autism. Autism currently affects 600,000 people in the UK.
“This finding provides another key step in our journey to ensure the earliest possible detection of autism, so that we can provide early interventions at a time when they can make the biggest impact to improve lives.”
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