According to the DSM-5, "the prevalence of specific learning disorder across the academic domains of reading, writing, and mathematics is 5-15% among school-age children across different languages and cultures. Prevalence in adults is unknown, but appears to be approximately 4%."
There are both environmental and genetic factors that have been identified for the development of specific learning disorder. Environmental factors include premature delivery, very low birth weight, and exposure to nicotine/smoking during prenatal development.
Research has found that a genetic component to specific learning disorder in that it tends to occur in families. The DSM-5 states that the risk of developing specific learning disorder in reading is 4-8 times higher and 5-10 times higher in math for those that have a first degree relative that has the disorder (parent or sibling).
Parents who have literacy problems or dyslexia are much more likely to have a child that has similar problems, which seems to indicate a combination of environmental and genetic factors.
Specific learning disorder has been found to commonly exist with several other disorders and conditions including:
- Communication Disorders
- Developmental Coordination Disorder
- Autism Spectrum Disorder
- Anxiety Disorders
- Depressive and Bipolar Disorders
Having one of these other conditions does not mean that someone cannot also be diagnosed with specific learning disorder, but it can make testing and diagnosis more difficult. It will be important for the clinician to determine if there are 2 separate conditions causing the symptoms or if the non-learning disorder condition is actually causing the academic problems. In that case, the child would not be diagnosed with specific learning disorder since the criteria require ruling out causation from another condition.