Dyslexia refers to any reading difficulty not associated with obvious problems (such as bad eyesight). Dyslexias include the inability to name letters, to read words or sentences, or to recognize words directly even though they can be sounded out. Dyslexia is not limited to reversing the order of letters in reading or writing, as is often implied in popular culture; it may, for instance, include unexpected spelling mistakes and unusual syntax, and may be associated with dyscalculia. Most theories focus on nonprimary areas in the frontal lobe and the temporal lobe. Recent studies have linked several forms of dyslexia to genetic markers.
It is said to be a neurological disorder with biochemical and genetic markers. Dyslexia was originally defined as a difficulty with reading and writing that could not be explained by general intelligence. One diagnostic approach is to compare their ability in areas such as reading and writing to that which would be predicted by his or her general level of intelligence.
People are diagnosed as dyslexic when their reading problems cannot be explained by a lack of intellectual ability, inadequate instruction, or sensory problems such as poor eyesight.
Only traditional educational remedial techniques have any record of improving the reading ability of those diagnosed with dyslexia. There is no evidence that colored lenses, any visual training, or similar proposed treatments are of any use. Anecdotal reports of success can be explained by other factors.
Even a few weeks of intense phonological training (often involving breaking down and rearranging sounds to produce different words) can help noticeably improve reading skills. The earlier the phonological regimen is taken on, the better the overall result. Advanced brain scans could identify children at risk of dyslexia before they can even read, although it is thought that simple tests of balance could do the same. It is claimed that many of the underlying causes of dyslexia are of a genetic nature and that there are no cures, only strategies to work around the causes of a person's dyslexia, however these two claims are disputed.
Researchers studying the brains of dyslexics have found that during reading tasks, dyslexics show reduced activity in the left inferior parietal cortex. It is anecdotally claimed that it is not that uncommon for dyslexics who have trained themselves to cope with their affliction, to develop uncannily efficient visual memories which aid in reading and comprehending large quantities of information much faster than is typical. Commonly dyslexics show 10 times more brain activity when reading. Sometimes, depending of the type and extent, also writing, listening and speaking. However, increased brain activity is not necessarily a sign of better processing. Conversely, some dyslexics may show a natural dislike of reading and, in consequence, compensate by developing unique verbal communication skills, inter-personal expertise, visual-spatial abilities and leadership skills.