By ROB WAUGH
UPDATED: 07:42 GMT, 12 January 2012
Internet addiction disrupts nerve wiring in the brains of teenagers, a study has found - causing a level of brain damage normally seen in heavy substance abusers.
Similar effects have been seen in the brains of people exposed to alcohol, cocaine and cannabis.
The discovery shows that being hooked on a behaviour can be just as physically damaging as addiction to drugs, scientists believe.
Brain scans showed significant damage to white matter in the brain, proving, the researchers claim, that 'behavioural' addictions can cause physical brain damage in the same way as drug addictions.
Internet addiction disorder (IAD) is a recently recognised condition characterised by out-of-control internet use.
Sufferers spend unhealthy amounts of time “online” to the extent that it impairs their quality of life.
Denied access to their computers, they may experience distress and withdrawal symptoms including tremors, obsessive thoughts, and involuntary typing movements of the fingers.
Until now research on IAD has focused on psychological assessments.
The new study, from China, used a Magnetic Resonance Imaging (MRI) technique to look at its effects on brain structure.
Scans were carried out on 17 internet-addicted adolescents and 16 non-addicted individuals, and the results compared.
In the IAD-diagnosed teenagers, the scientists found evidence of disruption to 'white matter' nerve fibres connecting vital parts of the brain involved in emotions, decision making, and self-control.
A measurement of water diffusion called 'fractional anisotropy' (FA) was used which provides a picture of the state of nerve fibres. Low FA was an indicator of poor nerve fibre structure.
The researchers, led by Dr Hao Lei from the Chinese Academy of Sciences in Wuhan, wrote in the online journal Public Library of Science ONE: 'Our findings