An ADHD test that could distinguish badly behaved children from those with the condition has been developed by scientists at Yale University.
Researchers have pinpointed brain differences in people with the attention disorder - including abnormal connectivity in neurons involved in memory and auditory processing - that could be used as biomarkers to confirm a diagnosis.
By identifying young patients, the test could lead to earlier diagnosis, treatment planning and surveillance of the condition.
Co-author Dr Huang Lin, of the Yale School of Medicine in New Haven, Connecticut, said: “There’s a need for a more objective methodology for a more efficient and reliable diagnosis.
“ADHD symptoms are often undiagnosed or misdiagnosed because the evaluation is subjective.”
The findings are based on magnetic resonance imaging (MRI) scans of almost 8,000 nine- and ten-year-olds in the US.
Changes found in almost all regions of the brain
Participants included 1,798 who had been diagnosed with ADHD. A statistical analysis was carried out of brain volume, surface area, white matter integrity and functional connectivity.
Dr Lin said: “We found changes in almost all the regions of the brain we investigated. The pervasiveness throughout the whole brain was surprising since many prior studies have identified changes in selective regions of the brain.”
Her team observed abnormal connectivity in neurons involved in memory and auditory processing, a thinner brain cortex and alterations in white matter - especially in the frontal lobe.
Dr Lin said: “The frontal lobe is the area of the brain involved in governing impulsivity and attention or lack thereof - two of the leading symptoms of ADHD.”
Data was significant enough that it could be used as input for machine learning models to predict an ADHD diagnosis. Artificial intelligence (AI) can analyse large amounts of MRI data.
Dr Lin said: “Our study underscores that ADHD is a neurological disorder with neuro-structural and functional manifestations in the brain, not just a purely externalised behaviour syndrome.”
The data also offers reassurance that the MRI biomarkers give a solid picture of the brain.
More objective diagnoses
She explained: “At times when a clinical diagnosis is in doubt, objective brain MRI scans can help to clearly identify affected children.
“Objective MRI biomarkers can be used for decision making in ADHD diagnosis, treatment planning and treatment monitoring.”
According to the Centers for Disease Control and Prevention, ADHD is one of the most common neurodevelopmental disorders in childhood.
It affects approximately six million American children between the ages of three and 17 years. It is estimated up to one in twenty school-aged children in the UK have the condition.
Diagnosis relies on a checklist completed by the child’s caregiver to rate the presence of ADHD symptoms, including trouble paying attention and controlling impulsive behaviours.
The study was presented at a meeting of the Radiological Society of North America in Chicago.