Scientists claim to have cracked why people with autism are around five times more likely to develop anxiety disorders.

Anxiety is one of the most common reasons why those with the condition seek support from health professionals.

Until now, it wasn't clear what triggered it - but a new study claims to have found an answer.

Researchers say high levels of anxiety can be explained by autistic people's difficulty in identifying and understanding their own emotions.

As a result, they suggest activities such as mindfulness could be particularly effective - and even revolutionise the treatment of anxiety in autism.

Anxiety is one of the most common reasons why those with autism seek support from health professional

Autistic spectrum disorders are a class of neuro-developmental conditions affecting around one in 100 children.

They are characterised by difficulties with social interaction, communication and language impairments, as well as stereotyped and repetitive behaviour.

People with autism have varying degrees of cognitive skills - ranging from people with significant delays to those of above-average intelligence.

Previous research suggests three main factors often contribute to people developing anxiety.

These include:

* difficulties coping with uncertainty

* problems in accepting emotional experiences

* alexithymia - the inability to recognise emotions in others and struggling to put feelings into words.

Earlier studies into anxiety in autism had focused on the first two of these factors - and the researchers on this paper say it is the first to consider the importance of alexithymia.

The personality trait - which can be found in the general population - is common in people with autism with around half also having the condition.

People with alexithymia are often unable to understand both their own emotions and those of others.

Social stigma towards people with autism has seen people with the condition described as 'cold, antisocial, and disinterested in others,' the scientists said.

The trait was the focus of research published earlier this year, which found people with autism are just as emotionally caring as everyone else but alexithymia stops them feeling empathy.

People with alexithymia are often unable to understand both their own emotions and those of others

In the new study, to explore how the personality trait might impact on anxiety in autism, they recruited 151 adults.

Of these, 76 people had been diagnosed with autism, while 75 had not.

Everyone completed a number of questionnaires that measured core autism symptoms.

These included anxiety, emotional acceptance, alexithymia, and intolerance of uncertainty.

And as expected, the questionnaire results confirmed people with autism experienced significantly higher levels of anxiety than people without the condition.

AUTISM IS NOT JUST A DISORDER OF THE BRAIN, RESEARCH SUGGESTS Until now, it was believed autism was cause by abnormal brain development. Now, scientists believe some aspects of the disorder may occur as a result of problems with nerves found in the arms, legs, hands, fingers and skin that send sensory information to the brain. Symptoms including being sensitive to touch, having difficulties with social interaction and anxiety might be caused by defects in the sensory nerves that run through the body. Harvard Medical School experts believe that in people with Autism spectrum disorder (ASD), these sensory nerves are defective due to gene mutations. This means the 'volume' is turned up all the way in these nerve cells, meaning touch is felt at an exaggerated, heightened level - and this can lead to anxiety and behavioural problems. Advertisement

The researchers then developed a statistical model to examine which factors could explain this relationship between anxiety and autism.

They say the model clearly showed that alexithymia, emotional acceptance and intolerance of uncertainty played a critical role.

In fact, these factors together accounted for 64 per cent of the relationship between autism and anxiety.

This suggests people with autism experience anxiety because they are more likely to react badly to their emotional experiences, while finding it difficult to identify and understand their emotions.

The research was a collaboration between academics from City University London, Newcastle University and Brigham Young University, Utah.

Co-author Dr Sebastian Gaigg, of City University, said: 'Our study is the first to show alexithymia and emotional acceptance could explain the high rates of anxiety in autism.

'Anxiety is one of the most common reasons why individuals with autism seek support from health professional.

'[Therefore] and our work has important implications for how anxiety might be treated effectively in those with the condition.

'In particular, we think mindfulness-based interventions may prove effective for alleviating anxiety in autism.

'Rather than worrying about the past or future, mindfulness-based therapies are designed to foster an individuals' awareness of moment-by-moment experiences, including current thoughts and experiences such as emotions and sensations.

'We therefore think such techniques would be effective in alleviating anxiety in autism by improving people's ability to identify, understand, and accept their emotions.'