dyslexia dyslexia dyslexia, previously known as word blindness, is a learning disability that affects reading. different people are affected to different 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. the difficulties are involuntary, and people with this disorder have a normal desire to learn. people with dyslexia have higher rates of attention deficit hyperactivity disorder (adhd), developmental language disorders, and difficulties with numbers. dyslexiaother namesreading disorder, alexiadyslexic handwriting in greekspecialtyneurology, pediatricssymptomstrouble readingusual onsetschool agetypessurface dyslexiacausesgenetic and environmental factorsrisk factorsfamily history, attention deficit hyperactivity disorderdiagnostic methodseries memory, spelling, vision, and reading testdifferential diagnosishearing or vision problems, insufficient teachingtreatmentadjusting teaching methodsfrequency3–7% dyslexia is believed to be caused by the interaction of genetic and environmental factors. some cases run in families. dyslexia that develops due to a traumatic brain injury, stroke, or dementia is sometimes called "acquired dyslexia" or alexia. the underlying mechanisms of dyslexia result from differences within the brain's language processing. dyslexia is diagnosed through a series of tests of memory, vision, spelling, and reading skills. dyslexia is separate from reading difficulties caused by hearing or vision problems or by insufficient teaching or opportunity to learn. treatment involves adjusting teaching methods to meet the person's needs. while not curing the underlying problem, it may decrease the degree or impact of symptoms. treatments targeting vision are not effective. dyslexia is the most common learning disability and occurs in all areas of the world. it affects 3–7% of the population; however, up to 20% of the general population may have some degree of symptoms. while dyslexia is more often diagnosed in boys, this is partly explained by a self-fulfilling referral bias among teachers and professionals. it has even been suggested that the condition affects men and women equally. some believe that dyslexia is best considered as a different way of learning, with both benefits and downsides. classification main article: pure alexia dyslexia is divided into developmental and acquired forms. acquired dyslexia occurs subsequent to neurological insult, such as traumatic brain injury or stroke. people with acquired dyslexia exhibit some of the signs or symptoms of the developmental disorder, but require different assessment strategies and treatment approaches. pure alexia, also known as agnosic alexia or pure word blindness, is one form of alexia which makes up "the peripheral dyslexia" group. signs and symptoms