There is no easy way to start a conversation about autism. Images spring to mind of a child sitting under his desk, rocking to and fro, unable to communicate and throwing tantrums. Or the film Rain Man and the misunderstood geniuses who struggle alone in the world. To many, a diagnosis of autism in a child is a family trag-edy and spells a lifetime of challenge. But a new study that investigates how Lego can help some autistic children to socialise is giving hope to families across Britain.

Brian is 13 and had Asperger syndrome (a type of autism), diagnosed four years ago. Highly intelligent with an advanced imagination, he would while away hours in his own world, but start flailing if he panicked or became overexcited. He was obsessive, could not sit still and did not understand social mores.

“Autistic children are very honest and don't understand social lies,” says his mother Gail Tyrrell, 43, from Cambridge. “If someone was acting happy but was in fact feeling very sad, he would ask them why they were feeling so sad. It could be tricky because people got frightened and thought him weird.”

Refusing to accept that his behaviour was not caused by bad parenting, his local primary school was unwilling to help. Although he passed his Sats tests, it would informally exclude him by sitting him in the corner of the classroom and threaten to keep him behind a year unless his behaviour improved. As a result, Gail enrolled Brian in the Lego club exercise conducted at Cambridge University's Autism Research Centre in 2005, along with 15 other children, mostly boys, aged 6 to 11, with an IQ over more than 70. For six months, they gathered for an hour a week to play with Lego. The idea behind the therapy, developed initially by Dan LeGoff in Philadelphia, was to encourage high-functioning children with autism or Asperger syndrome to communicate with each other and solve a problem by building in pairs or groups of three, according to set rules.

One child acted as the “engineer” and described the instructions, another as the “supplier” finding the correct pieces, and the “builder” put the pieces together. After a time, they would swap roles. Later, they would play “freestyle” in pairs, designing and building a model space rocket, for example, which allowed them to practise compromise, express their ideas clearly and take others' ideas into account.

Children started off building quick and easy models in pairs or threes with constant adult supervision before moving on to more complex models. All the while, they played according to Lego club rules, such as: if you break something, you fix it or ask for help; if someone else is using it, ask first before taking it; no yelling - keep your hands and feet to yourself.

Within weeks, Brian had changed from a confused boy without friends to a confident child. “By the end of the study, he was much happier at school - happy to stand up for himself and go and talk to people, even if they didn't want to talk to him,” says Gail. “He made friends at Lego club, which was great, and later met up to play at their houses, which was a big deal because at school he'd not been invited to parties.”

Brian was not alone. The study found that after six months, the children who had taken part generally showed fewer signs of autistic behaviour and were more confident in the playground than those with Asperger syndrome who had not joined in the research.

Gina Owens, who led the investigation and is planning to publish a Lego manual for professional use, said it was a very positive start. But she noted that it was a small study involving high-functioning children, so it was unlikely to be successful with more severely autistic children.

“It's a step on the way to helping them to live with autism and to improve their social skills by using their strengths and not seeing autism as a disability, but as a different way of thinking,” she says.

Lego was chosen as a means for children with autism to communicate with each other because it is a highly structured toy that appeals to their interest in systems, says Professor Simon Baron-Cohen, director of the Autism Research Centre, who is also involved in the research.

So what is autism, exactly? According to the National Autistic Society, more than half a million people in the UK have it, boys are four times as likely as girls to develop the disability and a fifth of children with autism have been excluded from school. But it is also an enigmatic disability that is lifelong and has no cure. While researchers believe that its roots are partly genetic and run in the family - Brian's sister and father both have Asperger syndrome - environmental factors, such as watching a lot of television when young, have also been linked to its development.

Although the disability often used to be wrongly attributed to poor parenting, Baron-Cohen says autistic spectrum disorders are not class-specific nor down to upbringing. Rather, he describes autism as a sort of “social dyslexia” whereby people find faces hard to read rather than words. People with autism find social occasions awkward, may interpret things too literally, often cannot understand jokes and generally have obsessive tendencies.

And as with dyslexia, Baron-Cohen believes that one day people living with autism will find that they too can live with the disability more easily through special support at school and with social skills programmes such as the Lego club.

“If a child has dyslexia, it is not considered a family tragedy. They just get specialist support and teachers are given lots of information on how to help them,” says the professor, who is also vice-president of the National Autistic Society. “We're trying to do the same thing for autism, with a whole range of learning materials to help them to circumvent the problem.”

As well as Lego therapy, Professor Baron-Cohen has also developed a DVD called Transporters, which superimposes real faces on to the fronts of animated vehicles, and is available on www.thetransporters.com. Working on the success of programmes such as Thomas the Tank Engine, Transporters encourages children with autism to look at human faces via a fascination with vehicles.

The beauty of the Lego club and Transporters, says Baron-Cohen, is that they use the obsessive tendency in high-functioning autistic children to good effect. In the early days of diagnosis, children were discouraged from pursuing obsessions and encouraged to do other things to widen their knowledge. Now, professionals such as Baron-Cohen believe that they should be encouraged to take their interests to extremes: “In the past, it was believed that obsessions got in the way of learning. Now, if a child is preoccupied with a system of learning, like maths, music or Lego, we say they should take it as far as they can, because they might be the passport to a job or a friendship. So we're turning that idea on its head and using the interest or obsession to help the child,” he says.

One person who believes that her obsession saved her life is Rozagy, a 37-year-old Russian woman, who now works as a journalist, artist and composer. Having had Asperger syndrome diagnosed by Baron-Cohen in 2006, Rozagy spent the first years of her life in Voronezh, Russia, suffering serious prolonged abuse at the hands of other children. The daughter of a composer, Gennady Stavonin, Rozagy attended music school from the age of 5, after school. She practised for hours every day but could never move on to a new score. “The repetition calmed me down. Doing music probably saved me from an institution, because classical music seemed to rewire my brain and make me calmer, and after that I would start talking,” said Rozagy. “I wasn't accepted at games and was bullied from the age of 9, and then I stopped talking. I would chew my hair and rock under the table, but I got very good grades.”

At 15, the bullying became too much and she went to music college. She would hear English spoken by students and dreamt of it as her haven. At 19, she moved to England and now lives in Birmingham with her two sons and husband, Sean.

Gail Tyrrell, whose son Brian is thriving, is also a firm believer in the socialising aspect of therapies such as Lego. After gaining a renewed confidence from the club, Brian went on to his secondary school, St Bede's, Cambridge.

“He's just a different person. He has friends who come over to play Dungeons and Dragons. Some have autism and some don't, because they've learnt the social skills to deal with all sorts of people who have their own deficits,” Tyrrell says.

And her message to parents whose children have autism diagnosed is not to be too downhearted. “We should not be mourning for an imperfect child, but for an imperfect world. They are a gift. So we just need to find the skills to get them through this imperfect world.”

*Owens, G., Granader, Y., Humphrey, A. & Baron-Cohen, S. (online early). LEGO® therapy and the Social Use of Language Programme: an evaluation of two social skills interventions for children with high functioning autism and Asperger syndrome. Journal of Autism and Developmental Disorders.