Anti-social behaviour can be a form of mental illness, claim scientists at Cambridge University.
The research team believes that adolescent males becoming unruly could be linked to a reduced level of the stress hormone cortisol. The boffins said that when people undergo the anxiety of experiences such as public speaking, sitting an exam or having surgery, cortisol usually increases.

 
The hormone enhances memory formation and is thought to help people behave more cautiously and regulate their emotions, particularly their temper and violent impulses. The research showed that disruptive male youths did not produce the same increase in cortisol when placed in a stressful situation. This suggests some cases of anti-social behaviour may be a form of mental illness caused by a chemical imbalance of cortisol in the brain and body, the scientists said.