Fresh research published by California State University suggests that teens addicted to social networking sites such as Facebook and Twitter are more likely to develop narcissistic tendencies and other behavioural issues.

Larry D. Rosen, professor of psychology at the university and author of “Poke Me: How Social Networks Can Both Help and Harm Our Kids”, warned that such sites carried a raft of negative effects, including a propensity for addicts to exhibit vain, aggressive and anti social behaviour.

Rosen pointed out that positive characteristics could also be attributed to the technology however, notably in giving shy young adults the confidence to socialise and empathise with others.

Scientists are have already established that both pre-teens and teens who use such sites on a daily basis are at increased risk of anxiety, depression and other psychological disorders.

Excessive use of such sites has also been linked to poorer academic results with pupils who check for updates during a 15min study period achieving lower grades.