Thousands of pupils with dyslexia in England are being let down by a system that does not diagnose their other learning difficulties, a leading academic has claimed.
Patricia Riddell, reader in psychology at Reading University, said schools would often label children as dyslexic but then not carry out further tests to discover whether they have problems, such as attention deficit hyperactivity disorder (ADHD) and other syndromes.
An estimated one in 10 pupils have dyslexia or another reading disorder.
Dr Riddell has carried out research with colleague Sue Cruddace that suggests the overlap between speech and language disorders and dyslexia is about 50 per cent.
In addition, about 25 per cent of dyslexic children have an attention deficit disorder and about 25 per cent have a movement disorder.
Dr Riddell fears that thousands of pupils are being left behind academically, because they are simply badged as dyslexic and are not receiving the other help they need.
"I would challenge the idea that teachers would recognise every disorder," she said. "Children go through school having been told they are dyslexic, and no one thought to find out if they are more than dyslexic, because there was no reason to.
"It is possible that a child who is playing up might be dyslexic, but it might not be picked up that it is an attention problem that is underlying the inability to read".
Andrea Bilbow, chief executive officer of ADDISS, the ADHD charity, agreed.
"(The problem is that) dyslexia is diagnosed by a psychologist, but ADHD is diagnosed by a psychiatrist. If a psychologist is not looking for ADHD, they are not going to find it," she said.
John Rack, head of research and professional development at Dyslexia Action, said the issue was of growing concern. He said it was important to ensure efforts focused not only on tackling literacy, but took account of any co-occurring difficulties, with no "simplistic use of labelling".
The Government has earmarked pound;10 million for dyslexia training in England, including 4,000 specialist teachers.