Problems with the brain’s ‘pruning’ brain connections could be why adolescents are at risk from a range of mental health disorders, new international research suggests today.
The study, led by researchers in the UK, China and Germany, may help explain why people are often affected by more than one mental health disorder. The findings, published in Nature Medicine, could lay the foundations to help identify those at greatest risk.
One in seven adolescents worldwide experiences mental health disorders, according to the World Health Organisation (WHO), and depression, anxiety and behavioural disorders are among the leading causes of illness. It is also common for adolescents to have more than one mental health disorder.
Professor Barbara Sahakian from the Department of Psychiatry at the University of Cambridge said: “Young people often experience multiple mental health disorders, beginning in adolescence and continuing – and often transforming – into adult life. This suggests that there’s a common brain mechanism that could explain the onset of these mental health disorders during this critical time of brain development.”
Researchers have identified a characteristic pattern of brain activity among these adolescents, which they have termed the neuropsychopathological factor (NP factor).
They examined data from 1,750 14-year-olds, from the IMAGEN cohort, a European research project investigating how biological, psychological, and environmental factors during adolescence may influence brain development and mental health.
They examined imaging data from brain scans taken while participants took part in cognitive tasks, looking for patterns of brain connectivity.
Adolescents who experienced mental health problems – regardless of whether their disorder was one of internalising or externalising symptoms, or whether they experienced multiple disorders – showed similar patterns of brain activity. These patterns, the NP, were mainly apparent in the frontal lobes.
The findings were confirmed when the research team replicated them in 1,799 participants from the US-based ABCD Study, a long-term study of brain development and child health, and by studying patients who had received psychiatric diagnoses.
When they examined genetic data from the IMAGEN cohort, they found the NP factor was strongest in individuals who carried a particular variant of the gene IGSF11 that is associated with multiple mental health disorders.
This gene plays an important role in synaptic pruning – and problems with this process may particularly affect the frontal lobes.
Dr Tianye Jia from the Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China and the Institute of Psychiatry, Psychology & Neuroscience, King’s College London, UK said: “As we grow up, our brains make more and more connections. This is a normal part of our development. But too many connections risk making the brain inefficient. Synaptic pruning helps ensure that brain activity doesn’t get drowned out in ‘white noise’.
“Our research suggests that when this important pruning process is disrupted, it affects how brain regions talk to each other. As this impact is seen most in the frontal lobes, this then has implications for mental health.”
The researchers say the discovery of the NP factor could help identify those young people at greatest risk of compounding mental health problems.
Professor Jianfeng Feng from Fudan University in Shanghai, China, and the University of Warwick, UK, added: “We know that many mental health disorders begin in adolescence and that individuals who develop one disorder are at increased risk of developing other disorders, too. By examining brain activity and looking for this NP factor, we might be able to detect those at greatest risk sooner, offering us more opportunity to intervene and reduce this risk.”
Chao X et al. A shared neural basis underlying psychiatric comorbidity. Nature Medicine 24 April 2023; doi: 10.1038/s41591-023-02317-4
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