“Learning disabilities result from general problems in the brain rather than specific genetic or neurological defects, the British Association Festival of Science in Salford was told on Tuesday.

A large but unidentified group of genes, each with very small effects on overall brain function, work together to determine most of mental ability, says Robert Plomin, at the Institute of Psychiatry in London.

If Plomin’s theory proves correct, common learning disabilities such as dyslexia will need a dramatic redefinition. Dyslexia is commonly defined as a reading problem in someone who has otherwise normal intelligence.

In fact, Plomin disputes the idea of learning disabilities at all, saying instead that these people simply fall at the lower end of the spectrum of cognitive ability.” New Scientist