Adolescent mental health disorders are linked to brain connections ‘pruning’

A wide range of mental health conditions that start around adolescence may be caused by problems with the brain’s capacity to “prune” itself into unnecessary connections. 

An international partnership led by academics from the United Kingdom, China, and Germany may help explain why people are frequently impacted by more than one mental health issue and may assist in identifying those at the highest risk in the future.

According to the World Health Organisation (WHO), mental health disorders affect one in seven teenagers (10–19 years old) globally. Among the most common causes of sickness and impairment among young people are depression, anxiety, and behavioral problems, including attention deficit hyperactivity disorder (ADHD). Adolescents frequently have multiple mental health illnesses.

Adolescents with mental health difficulties showed similar patterns of brain activity, regardless of whether their disease was one of the internalizing or externalizing symptoms or if they had multiple symptoms like sadness and concern. ‘Externalising’ symptoms, including aggressive behaviors, are a symptom of other disorders, like attention deficit hyperactivity disorder (ADHD).

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 a common brain mechanism could explain the onset of these mental health disorders during this critical time of brain development.”

According to a new study, The “neuro psychopathological factor,” or NP factor for short, is a distinctive pattern of brain activity among these adolescents. 

The team examined data from 1,750 14-year-old adolescents from the IMAGEN cohort, a European study examining how biological, psychological, and environmental factors may affect brain development and mental health during adolescence.

They examined patterns of brain connection in imaging data from brain scans collected while participants performed cognitive tasks.

They discovered that the NP factor was highest in people with a specific variation of the gene IGSF11, which has previously been linked to various mental health issues.

The NP factor patterns were most visible in the frontal lobes, the part of the brain responsible for executive function, which regulates, among other things, flexible thinking, self-control, and emotional behavior.

This gene plays an important role in synaptic pruning, a process that eliminates superfluous brain connections called synapses. Pruning issues may be especially problematic in the frontal lobes, the last brain parts to grow in teenagers and young adults. 

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, London, UK, said: “As we grow up, our brains make more and more connections, but too many connections risk making the brain inefficient. Synaptic pruning helps ensure that brain activity doesn’t get drowned out in ‘white noise.”

He also said, “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.”

According to the researchers, identifying the NP factors help in identifying young people who are most at risk of compounding mental health problems.

Professor Jianfeng Feng from Fudan University in Shanghai, China, and the University of Warwick, UK, said, “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.”

The National Natural Science Foundation of China, the European Union, the National Institute for Health and Care Research (UK), and the National Institutes of Health (USA) funded the study.

Journal Reference:

1. Xie, C., Xiang, S., Shen, C., Peng, et al. A shared neural basis underlying psychiatric comorbidity. Nature Medicine. DOI: 10.1038/s41591-023-02317-4