Specified Learning Disorder

Prevalence

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%.

Prematurity or very low birth weight increases the risk for specific learning disorder, as does prenatal exposure to nicotine.

Specific learning disorder appears to aggregate in families, particularly when affecting reading, mathematics, and spelling.
The relative risk of specific learning disorder in reading or mathematics is substantially higher (e.g., 4-8 times and 5-10 times higher, respectively) in first-degree relatives of individuals with these learning difficulties compared with those without them.
Family history of reading difficulties (dyslexia) and parental literacy skills predict literacy problems or specific learning disorder in offspring, indicating the combined role of genetic and environmental factors.
There is high heritability for both reading ability and reading disability in alphabetic and nonalphabetic languages, including high heritability for most manifestations of learning abilities and disabilities (e.g., heritability estimate values greater than 0.6).

Difficulties learning and using academic skills, as indicated by the presence of at least one of the following symptoms that have persisted for at least 6 months, despite the provision of interventions that target those difficulties:

Inaccurate or slow and effortful word reading (e.g., reads single words aloud incorrectly or slowly and hesitantly, frequently guesses words, has difficulty sounding out words).
Difficulty understanding the meaning of what is read (e.g., may read text accurately but not understand the sequence, relationships, inferences, or deeper meanings of what is read).
Difficulties with spelling (e.g., may add, omit, or substitute vowels or consonants).
Difficulties with written expression (e.g., makes multiple grammatical or punctuation errors within sentences; employs poor paragraph organization; written expression of ideas lacks clarity).
Difficulties mastering number sense, number facts, or calculation (e.g., has poor understanding of numbers, their magnitude, and relationships; counts on fingers to add single-digit numbers instead of recalling the math fact as peers do; gets lost in the midst of arithmetic computation and may switch procedures).
Difficulties with mathematical reasoning (e.g., has severe difficulty applying mathematical concepts, facts, or procedures to solve quantitative problems).

The affected academic skills are substantially and quantifiably below those expected for the individual’s chronological age, and cause significant interference with academic or occupational performance, or with activities of daily living, as confirmed by individually administered standardized achievement measures and comprehensive clinical assessment.

The learning difficulties begin during school-age years but may not become fully manifest until the demands for those affected academic skills exceed the individual’s limited capacities (e.g., as in timed tests, reading or writing lengthy complex reports for a tight deadline, excessively heavy academic loads).

The learning difficulties are not better accounted for by intellectual disabilities, uncorrected visual or auditory acuity, other mental or neurological disorders, psychosocial adversity, lack of proficiency in the language of academic instruction, or inadequate educational instruction.