Brain scans of pre-school children may allow detection of dyslexia before students even start to read, researchers from America have suggested.
The team from MIT's McGovern Institute for Brain Research found early markers of dyslexia on scans that have already been seen in adults with the condition.
Wider use of scans of the arcuate fasciculus area of the brain could allow early diagnosis and intervention, lead researcher Prof John Gabrieli has suggested.
"This brain area fits with a lot of what we already know. So it's a good candidate," he said. "We don't know yet how it plays out over time, and that's the big question.
"We do not know how many of these children will go on to develop problems. But anyway, we want to intervene before that, and the younger you do that the better. We already know that reading programmes and interventions can really help."
Shrinkage of this brain region
Among the 40 school-entry children they studied they found some had shrinkage of this brain region, which processes word sounds and language.
They asked the same children to do several different types of pre-reading tests, such as trying out different sounds in words. Those children with a smaller arcuate fasciculus had lower scores.
It is too early to say if the structural brain differences found in the study are a marker of dyslexia. The researchers plan to follow up groups of children as they progress through school to determine this.
Cluster of dyslexia indicators
A spokeswoman for the British Dyslexia Association said brain imaging was providing "increasing evidence" of notable differences between the brains of people with and without dyslexia.
"It is particularly exciting to envisage a future where this technology could be part of a cluster of indicators that would identify a risk of dyslexic difficulties," she said.
But she said there needed to be far more research to determine if in the future it might be possible to diagnose dyslexia with a brain scan.