Europe South Asia Asia Pacific Americas Middle East Africa BBC Homepage World Service Education



Front Page

World

UK

UK Politics

Business

Sci/Tech

Health

Education

Sport

Entertainment

Talking Point

In Depth

On Air

Archive
Feedback
Low Graphics
Help

Thursday, April 22, 1999 Published at 07:35 GMT 08:35 UK


Health

Dyslexia linked to nerve damage

Dyslexics have trouble with reading

Dyslexia may be caused by damage to nerve cells in the brain, a scientist has claimed.

Dr John Stein, from Oxford University, has found damage in the optic nerves of dyslexic children, and believes other areas of the brain's nervous system may also be affected.

His controversial idea also appears to account for other trouble experienced by some dyslexic children, such as subtle hearing problems.

Dr Stein, according to New Scientist magazine, also believes that the damage occurs in the brain of the developing foetus and may be caused by the mother's immune system.

Dyslexia sufferers have trouble reading and writing, even though they might be intellectually bright.

Because there is so much natural variability in how fast children learn to read and write, the condition is often not properly diagnosed.

People with dyslexia have no difficulty understanding the meaning of words, recognising individual letter shapes, and seeing anything other than text.

This has led many scientists to say that dyslexia is caused by a specific problem with the language centres in the brain.

Rapid changes


[ image: Dyslexics can be clumsy and uncoordinated]
Dyslexics can be clumsy and uncoordinated
But Dr Stein believes the condition arises from an inability to sense the most rapid changes in the world around us, particularly in what we see and hear.

He believes that during foetal development, something damages or attacks the vulnerable young nerve cells responsible for relaying information about fast-changing events.

If he is right, this could explain a whole host of other lesser known problems that researchers and people who work with dyslexic children have associated with the condition, such as clumsiness, poor balance and coordination.

To test his theory, Dr Stein asked people to watch two computer screens displaying tiny dots moving around at random.

He found that dyslexics were less likely to spot synchronised movement of the dots than people who were not suffering from the condition.

Dr Stein found that the poorer the ability to spot a change in motion, the worse the reading and spelling.

Large nerve cells

Dr Stein believes that dyslexics suffer from a defect in a set of very large nerve cells known as magno-cells.

These cells rapidly transmit electrical impulses from the retina in the eye to the brain so that it can recognise rapid changes or movement.

Other researchers have shown that the magno-cells in dyslexics operate more slowly than usual, and postmortem examinations have revealed abnormalities in the shape and position of the cells.

The magno-cell defects could make reading difficult because they make it impossible to process the quick eye movements needed to decipher text.

Dr Stein has found that many dyslexics find it difficult to hold their eyes steady between movements, probably because the magno-cells are failing to send proper signals to the brain.

Dr Stein believes that the magno-cells are damaged in the womb by antibodies produced by the mother's immune system which attack the cells and stunt their development.

He believes other nervous pathways governing hearing and coordination may also be affected.



Advanced options | Search tips




Back to top | BBC News Home | BBC Homepage | ©


Health Contents

Background Briefings
Medical notes

Relevant Stories

21 Apr 99 | Health
Mothers may cause disease

17 Feb 99 | Health
Cancer-killer turns on immune system

08 Feb 99 | Health
Immune system 'causes heart failure'

15 Oct 98 | Health
Immune system 'attacked by mobile phones'

22 Jun 98 | Health
Immune system blamed for Chronic Fatigue Syndrome





Internet Links


The Dyslexia Institute

Dyslexia links

British Dyslexia Association

New Scientist


The BBC is not responsible for the content of external internet sites.




In this section

Disability in depth

Spotlight: Bristol inquiry

Antibiotics: A fading wonder

Mental health: An overview

Alternative medicine: A growth industry

The meningitis files

Long-term care: A special report

Aids up close

From cradle to grave

NHS reforms: A guide

NHS Performance 1999

From Special Report
NHS in crisis: Special report

British Medical Association conference '99

Royal College of Nursing conference '99