Researchers at the University of Cambridge have found that different learning difficulties don’t correspond with specific brain regions as previously believed. Children’s difficulties are more closely linked to poor connectivity between brain ‘hubs.
Around 14-30% of adolescents and children worldwide have learning difficulties that are severe enough to warrant additional support. These difficulties are often linked to cognitive and/or behavior problems. Children who struggle at school may be diagnosed with a learning disability or learning difficulty, such as dyslexia or dyscalculia.
Scientists have struggled for years to pinpoint the brain regions responsible for these difficulties. Many brain regions have been implicated in studies. ADHD, for instance, has been linked with the anterior cingulate cortex, caudate nuclear, pallidum.striatum. cerebellum. Prefrontal cortex, premotor cortex, and most of the parietal brain.
One explanation could be that each diagnosis is different between individuals, and each one involves different combinations brain regions. Scientists at the MRC Cognition and Brain Sciences Unit University of Cambridge have proposed a more intriguing explanation: these difficulties are not caused by specific brain areas.
To test their hypothesis, researchers used machine-learning to map brain differences among almost 479 children. 337 children were referred with learning-related cognitive disorders and 142 from a control sample. The algorithm used data from a wide range of cognitive, learning, and behavioural measures. It also used brain scans using magnetic resonance image (MRI) to interpret the data. The results were published today in Current Biology.
The brain differences were not mapped onto the labels that children were given, so there was no way to predict ASD or ADHD. They also found that the brain regions didn’t predict specific cognitive difficulties. For example, there was no brain region that predicted memory problems or language problems.
Instead, the team discovered that children’s brains were organized around hubs. This is similar to a traffic system or social network. Children with well-connected brain hubs experienced cognitive difficulties such as poor listening skills or no cognitive difficulties at all. Children with poorly connected hubs, such a train station with few connections or none, have severe cognitive problems.
“Scientists have claimed for decades that certain brain regions predict having a particular learning disorder, but we’ve proven that this is not true,” said Dr Duncan Astle who was the senior author of the study. “In fact, it is much more important to think about how these brain regions are connected, specifically whether they are connected via Hubs. We believe that the connectedness of these hubs was strongly related to learning difficulties. This is because hubs play a key part in sharing information between brain regions.
Dr Astle stated, “One implication of their research is that it suggests interventions should be less dependent on diagnostic labels.”
Families are important to receive a diagnosis. It can help to give professional recognition of the child’s difficulties and open up the door for specialist assistance. However, specific interventions, such as from teachers, can be distracting.
“It is better to look at their cognitive problems and how they can be supported. This could include using specific interventions to improve listening skills and language competencies or interventions that would be beneficial for the whole class such as how to reduce working memories during learning.
These findings could explain why drugs for treating developmental disorders have not been effective. ADHD treatment, such as Ritalin (Methylphenidate), appears to reduce hyperactivity but not to improve cognitive ability or educational progress. Although drugs tend to target certain types of nerve cells, they would have little effect on an organisation that has been around for many years.
This is the first time hubs and their connections were shown to play a crucial role in learning disabilities and developmental disorders. However, their importance in brain disorders has been increasing in recent years. Researchers at Cambridge have previously demonstrated that hubs play an important role for mental health disorders that develop in adolescence like schizophrenia.
The Medical Research Council funded the study.