Dyslexia, also known as
reading disorder, is characterized by trouble with
reading despite normal
intelligence.
[2][3] Different people are affected to varying degrees.
[4] 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.
[4][5] Often these difficulties are first noticed at school.
[6] When someone who previously could read loses their ability, it is known as
alexia.
[4] The difficulties are involuntary and people with this disorder have a normal desire to
learn.
[4]
Dyslexia is believed to be caused by both
genetic and environmental factors.
[6] Some cases run in families.
[4] It often occurs in people with
attention deficit hyperactivity disorder (ADHD) and is associated with similar
difficulties with numbers.
[6] It may begin in adulthood as the result of a
traumatic brain injury,
stroke, or
dementia.
[2] The underlying mechanisms of dyslexia are problems within the
brain's language processing.
[4] Dyslexia is diagnosed through a series of tests of memory, spelling, vision, and reading skills.
[7] Dyslexia is separate from reading difficulties caused by
hearing or
vision problems or by insufficient
teaching.
[6]
Treatment involves adjusting teaching methods to meet the person's needs.
[2] While not curing the underlying problem, it may decrease the degree of symptoms.
[8] Treatments targeting vision are not effective.
[9] Dyslexia is the most common
learning disability and occurs in all areas of the world.
[6][10] It affects 3–7% of the population;
[6][11] however, up to 20% may have some degree of symptoms.
[12] While dyslexia is more often diagnosed in men,
[6] it has been suggested that it affects men and women equally.
[10] Some believe that dyslexia should be best considered as a different way of learning, with both benefits and downsides.
[13][14]