Baby talk could help spot autism years before symptoms begin, according to new research. Parents often use playful, emotional, exaggerated tones - dubbed 'motherese' - to capture a child's attention.
Now a study has found it opens the door to identifying behavioural problems when therapy works best. Eye-tracking tests showed those who did not respond had weaker social and language abilities.
Corresponding author Professor Karen Pierce, of California University in San Diego, said: "We know the earlier we can introduce treatment, the more effective it is likely to be. But most children don't get a formal diagnosis until around the age of three or four.
"There is a real need for easy and effective tools that can be used on young children. Eye-tracking is a great place to start."
The study in JAMA Network Open offers hope of a screening program. In experiments, 653 tots aged one to two years old were exposed to two one minute videos featuring a woman speaking motherese or abstract scenes. Their eyes controlled which one played.
Participants without ASD (autism spectrum disorder) showed consistently high interest in the former - spending an average 80 percent of the time watching it. They largely ignored the latter which showed a busy highway, abstract shapes and numbers and had accompanying electronic music.
But fixation levels of peers diagnosed with ASD spanned the full range of concentration levels - some focusing 100 percent on the random images. A group who fixated on motherese less than 30 percent of the time could be accurately identified as having ASD through this measurement alone.
These children also showed lower scores on subsequent tests of language and social skills. Toddlers who had ASD but still spent a majority of the time attending to motherese displayed greater social and language abilities, highlighting the diversity within the ASD population.
Whether less attention to motherese is the cause of reduced sociability or merely a symptom has yet to be determined. But it appears to be a highly accurate biomarker for a subtype of the condition. Prof Pierce said: "The fact we can reliably identify children with autism using such a simple and rapid eye-tracking test is really remarkable.
"In future we hope to use a child's attention to motherese as a clue for which treatments they may most benefit from and as a tool for measuring how well those treatments work."
Children with ASD have problems with communicating, social interaction and are prone to repetitive behaviours. But most cases are not confirmed until after the age of four meaning therapy is started later - delaying their potential impact.
Studies have shown baby talk stimulates children's attention and learning, helping them develop language skills and emotional reactivity. It is characterised by higher and wider pitch, slower speech rate and a 'sing song' pattern of intonation that differentiates it from the more monotone style used when adults speak normally.
Parents use normal language but make it simpler by repeating words and speaking slower. They also exaggerate facial expressions - opening the mouth wider, raising eyebrows and smiling a lot.
Scientists claim talking to babies gives them advantages in life far beyond a larger vocabulary. They say chatting to infants under the age of one helps them make friends, as well as making them brighter because they are better able to discover the world around them.
If autistic toddlers do not pay as much attention to this speech style, it might affect their social skills later in life. The eye-tracking test could be beneficial for early ASD screening, diagnosis and prognosis, and help clinicians identify which treatments would be most useful for the child.
Autism is estimated to affect around 700,000 children and adults in the UK.
