CHILDREN who struggle with arithmetic may be suffering from the mathematical form of dyslexia, a crippling inability to handle numbers.

Dyscalculia may affect as many as one in 20 people and make their lives a misery, Brian Butterworth, professor of cognitive neuropsychology at University College London, told the British Association for the Advancement of Science yesterday. “They are misdiagnosed as stupid,” he said.

“Their teachers think they are stupid; they think they are stupid. We have done focus groups with nine year-olds and it is heartbreaking.”

Children with the disability needed to be reassured that it was akin to colour-blindness and they should be spared the daily humiliation of maths lessons by being taught separately, he said.

The disability was innate and had nothing to do with the way children were taught or their use of calculators. They simply lacked a proper sense of number, tended to add using their fingers and could not do simple arithmetic such as subtracting one two-digit number from another.

Entry to university was tricky because many could not pass the maths GCSE. Those who did get in went on, however, to get good degrees.

Professor Butterworth cited the case of a woman with a First in Philosophy who had serious dyscalculia. Elsewhere he has written about a man who had a degree in philosophy but still could not add up. Shopping was a constant embarrassment because he did not understand prices, had no idea how much money to tender or what the right change ought to be.

At the association festival at Salford University experts in the disability suggested that there was a link between dyscalculia and a primitive number sense possessed by humans and animals that enabled them to make instant assessments of the numbers of objects in a group without having to count.

This process was called subitizing, Professor Butterworth said.

In what he described as the largest such study ever carried out, he investigated visitors to the science exhibition Explore At Bristol.

A total of 18,000 visitors were shown a display of dots on a screen and asked to say whether a number — two, say — corresponded to the dots.The results showed that there did appear to be a distinct mechanism for the instant recognition of small numbers and that women were slightly better at it than men. Men and women were equally good when there were more than four dots and they had to be counted.

The evidence is that dyscalculics are bad at the instant judgment of numbers, possibly because of poor brain development in the parietal lobes at the back of the brain that are involved in the process.

Stanislas Dehaene of the French National Institute of Health and Medical Research said that he had used brainimaging methods to show that there were specific cells in this part of the brain whose job it was to represent numbers. His experiments showed that girls with Turner’s syndrome, a genetic disease, suffered dyscalculia and disorganisation of this part of the brain.

Elizabeth Isaacs, of the Institute of Child Health in London, said that very low birthweight babies who appeared quite normal but were poor at arithmetic had a deficiency of a protein, taurine, in their blood soon after birth. Brain scans showed that this group also had less grey matter in the parietal lobes.

Sum of all fears

There is no simple test for dyscalculia, but children who suffer from it often have problems:

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