 Dyslexia , also known as reading disorder , is characterized by trouble with reading despite normal intelligence . Different people are affected to varying degrees . Problems may include difficulties in spelling words , reading quickly , writing words , " sounding out " words in the head , pronouncing words when reading aloud and understanding what one reads . Often these difficulties are first noticed at school . When someone who previously could read loses their ability , it is known as alexia . The difficulties are involuntary and people with this disorder have a normal desire to learn . 
