Asked by: Annabel Ivin, Chepstow
People don’t exactly ‘get’ dyslexia because it’s not an infectious disease or a result of brain damage (loss of reading or writing ability after brain damage is called alexia). Rather, it’s a deficit in reading, writing and other abilities that usually shows up when children struggle to master these skills at school. Many children find reading hard because of low intelligence, but dyslexia is diagnosed when reading ability is poor compared with general intelligence. Between five and 17 per cent of the population are affected, although diagnosis can be controversial. There’s a genetic component to dyslexia, but many competing theories about what the genes do. Some point to deficits in the cerebellum, which controls fine movements; others to problems in the visual system, in attention systems or elsewhere in the brain. We should remember that human brains did not evolve in a world full of numbers, letters and books. So perhaps it is not surprising that not all of us are well suited to acquiring these modern skills.