Researchers use two categories to differentiate types of dyslexia based on potential causes.
The first category is developmental. Developmental dyslexia is present from birth and is separated into two sub-categories: primary and secondary.
- Primary dyslexia has been linked to certain inherited genes that contribute to reading and language functions in the brain. Chances are high that a person with dyslexia has one or more close relatives who also have it.
- Secondary dyslexia is attributed to brain development issues that happen in the early stages of pregnancy.
The second category of dyslexia is acquired. Secondary dyslexia results from a traumatic brain injuries, serious illnesses, or strokes. It can develop at any time in a person's life.
Dyslexia is typically diagnosed by a licensed educational psychologist, neurologist or any other medical professional that may be qualified to provide a formal diagnosis.