Many children exhibit autism-like traits, even if their symptoms are not severe enough for a clinical diagnosis, new research suggests.
Researchers from the University College London (UCL) Institute of Child Health found a gradual progression from children who do not have autistic symptoms to those with severe behavioural and emotional impairments that are hallmarks of autism.
If autism was a distinct condition, such a spectrum would not be possible, the researchers argue.
The research, which included more than 8,000 eight-year-old children, also found that even children who have mild autistic symptoms are more likely to experience the behavioural, emotional and social difficulties common in autistic patients.
"Clinicians and those involved in education need to be aware that there are children who do not have autism but who nevertheless have somewhat elevated levels of autistic traits," study authors Prof. David Skuse and Dr. William Mandy, said in a statement. "Our research suggests that that these children are at slightly greater risk of developing behavioural and emotional problems."
The findings are published in the Journal of the American Academy of Child and Adolescent Psychiatry.
According to the researchers, more scientists now believe that, rather than being a distinct group, kids with autism actually exhibit extreme versions of traits that most people experience.
Autism is defined as a spectrum of disorders that can cause mild to severe social, emotional and behavioural impairment.
There is no known cause or cure. However, experts believe that early intervention with behavioural therapy can improve a patient's symptoms.
According to the researchers, their study suggests that children who do not receive a formal autism diagnosis will be unable to access treatment.
In an accompanying editorial, Prof. John Constantino of Washington University, said the findings have implications for doctors and families of children who exhibit behavioural difficulties that do not warrant an autism diagnosis.
"The approach of teachers and family members to such children can vary dramatically on the basis of the perceived origins of the behaviour, and recognition of the contribution of subthreshold autistic impairments can result in far more appropriate and supportive responses than typically occur when antisocial motives are presumed," Constantino wrote.
