Adolescents addicted to the Internet undergo changes in the brain that could lead to addictive behaviour or tendencies, researchers at the University College, London, have said in a review of brain imaging studies over the past decade.

Their review, although based on brain imaging studies on only 237 volunteers from East Asian countries, has suggested that Internet addiction affects multiple neural networks in adolescents’ brains, increasing activity in some networks and decreasing it in other networks.

Internet addiction, for instance, decreases activity in parts of the brain called the executive control network, involved in active thinking and goal-directed behaviour. The researchers also noted a complex mix of increased and decreased activity in parts of the brain called the default mode network, which is activated when people are not engaged in any specific tasks but allow their minds to wander at rest.

The findings suggest that the altered neural activity associated with Internet addiction could lead to "potentially negative behavioural and developmental changes that could impact adolescents' lives", Max Chang, a researcher at the UCL and the review’s co-author, said in a media release.

“The research has suggested that functional connectivity changes seen in Internet addiction are similar to gambling and substance addiction,” Chang told The Telegraph via email. “The disruptions in functional connectivity in brains of adolescents with Internet addiction alter the systems that control crucial behavioural functions such as cognitive control, impulsivity, and reward valuation.”

Listing possible impacts, Chang said, adolescents with Internet addiction "may struggle to maintain relationships and social activities, lie about online activity, or experience irregular eating or disrupted sleep".

Adolescence is a crucial developmental stage during which people go through changes in their biology, cognition and personalities, Chang said.

Although the mechanisms are not fully clear, the researchers said, the observed changes in the activity of neural networks have the capacity to influence several aspects of adolescents’ development, Chang and senior co-author Irene Lee wrote in their review, published in the research journal PLOS Mental Health on Tuesday.

“We would advise that young people enforce sensible time limits for their daily Internet usage and ensure that they are aware of the psychological and social implications of spending too much time online,” Lee said in a media release from the UCL.

The review by Chang and Lee covered a set of earlier studies conducted in China, South Korea and Indonesia on 237 young people aged between 10 and 19 years and diagnosed with Internet addiction.

Over 80 per cent of adolescents across Asia, the UK and the US have access to the Internet and earlier studies have suggested that Asian countries have a higher prevalence of Internet addiction (5.7 per cent) than European countries (2.7 per cent).

The findings come amid concerns among researchers that large proportions of college students and other young people spend long periods on the Internet, disrupting their studies or work.

A technical review in 2021 of 50 studies from 19 states in India found that 20 per cent to 40 per cent of college students were at risk of Internet addiction.