Youngsters with specific language impairment (SLI) are unable to verbally express their feelings and find it difficult to understand what others are saying due to a developmental problem with their language. However they show no physical signs of the disorder, have otherwise normal intellectual ability and do enjoy socialising, so often appear to other people as just 'unusual'. This can lead to them being ostracised or even attacked by their peers.

SLI affects 4-7% of children - approximately 520,000 in the UK - which is four times more than autism. Little is known about its cause and neurological basis but it affects twice as many boys than girls and tends to run in families.

Almost half of the 16 year olds with SLI recalled being teased or bullied when they were younger in interviews for a study by Professor of Child Language and Learning Gina Conti-Ramsden and her colleague Dr Emma Knox.

In addition 13% of the teenagers had experienced persistent bullying across time.

A group of teenagers without communication difficulties also reported being teased and bullied when they were younger, but this constituted less than a quarter of those interviewed.

Professor Conti-Ramsden said: "For every teenager being bullied at school, there are two teenagers with communication difficulties who are having similar experiences."

The study, published in Educational and Child Psychology and funded by the Nuffield Foundation, investigated the bullying experiences of 139 young people with SLI and 124 young people who were developing typically. The groups were asked about their experiences currently at 16 years old, and retrospectively.

Dr Knox said: "Our investigation also showed that young people who experience bullying can often become anxious and depressed in adolescence.

"Our findings emphasise the continued need for educators and professionals working with young people with SLI to support them not only with their academic experiences, but also with the associated difficulties that bullying may bring. Young people with SLI may lack the necessary communication skills to enable them to report bullying and talk about their experiences, leaving them to suffer in silence.

Professor Conti-Ramsden concluded: "Society is aware of the negative effects of bullying and this has led to anti-bullying policies in schools, organisations and the media. However, we cannot be complacent.

This study raises awareness of a vulnerable group of young people for whom the applicability of anti-bullying strategies is particularly great. An awareness of the associated features of bullying victims, such as anxiety, depression or behavioural problems, may help teachers to identify victims and support them appropriately.