Dyslexia is offer characterized by the child or adult's struggle with reading and/or writing. There are a few explanations of what causes dyslexia. According to MedicineNet, there are three main types of dyslexia, categorized by what caused them: trauma dyslexia, primary dyslexia, and developmental dyslexia. In addition, dyslexia is also categorized by the issues the individual is having. These include visual and auditory dyslexia.
Trauma dyslexia, the first type, usually happens after the individual has gone through brain trauma or brain injury. This may be for a variety of reasons, such as a car accident or a fall from a tall ladder. Trauma dyslexia is usually seen in adult patients and most children do not suffer from it. The trauma is usually at the area of the brain that controls an individual's ability to read and to write.
The next type of dyslexia (again, according to MedicineNet) is called Primary Dyslexia. Instead of a brain injury or trauma, Primary Dyslexia is caused by a dysfunction of the cerebral cortex, or left side of the brain. This type of dyslexia is genetic and is hereditary and is sometimes correlated with left-handedness (however, not all left-handed children are dyslexic and vice versa). Boys are usually more likely to have Primary Dyslexia than girls are. This type of dyslexia does not improve or get worse with age. Patients usually read at or below a fourth-grade level and continue to struggle with writing, reading, and spelling into their adulthood.
The last type of dyslexia is called Developmental (or Secondary) Dyslexia and is assumed to be caused by hormonal development during the early stages of development in the uterus. Developmental dyslexics usually improve and have less symptoms as they get older. This type of dyslexia is also more common in boys.
Furthermore, as mentioned above, individuals with a certain type of dyslexia may also be categorized by what type of skill they are struggling with. Visual dyslexia is constituted as a struggle with the ability to write numbers, letters, and words in their correct order and style. Many dyslexics often may read words backwards or write (or say) words out of order in a sentence. Auditory dyslexia is the struggle with the sounds of individual letters or words. Auditory dyslexics cannot pronounce the sounds of letters and words correctly because they do not hear or see them in the right way. Auditory dyslexia also may be caused by hearing and ear problems that start from an early age. If a child is unable to hear the correct pronunciation of words and letters, than they will in fact have trouble learning them and may develop a case of auditory dyslexia. However, it's important to note that this isn't always the case. Auditory dyslexics don't always have hearing problems and those with hearing problems may not have dyslexia.
What causes dyslexia definitely depends on the individual's own circumstances. A dyslexia patient may suffer from a combination of the above causes of dyslexia and therefore may have a more severe (or long-standing) case than others.