Chapter 48 Learning Disabilities
PATHOPHYSIOLOGY
Learning disabilities are a group of neurologic disorders that affect an individual’s ability to store, process, and produce information. Learning disabilities significantly interfere with educational achievement and performance, and they create a gap between one’s capabilities and performance. Impairment may be in the area of reading, writing, spelling, or mathematical functions. The most commonly identified learning disability is reading disability. Intelligence is generally average or above average in these children. However, academic achievement is markedly below what is expected given the person’s intellect, age, and educational opportunities.
Etiologic factors associated with learning disabilities include genetic predisposition, perinatal and birth injuries, and medical conditions occurring in infancy or childhood, such as head injury, malnutrition, or poisoning. Late effects of cranial irradiation, as well as alcohol or tobacco use during pregnancy, have also been known to contribute to learning disabilities. Mental retardation, emotional or behavioral disorders, and autism are not learning disabilities. Environmental, socioeconomic, and cultural disadvantages do not produce learning disabilities. Learning disabilities can be categorized into several types: reading disorder, mathematics disorder, disorder of written expression, and learning disorder not otherwise specified (Box 48-1).
Box 48-1 Learning Disabilities: DSM-IV Criteria
Reading Disorder DSM-IV Criteria
A. Reading achievement, as measured by individually administered standardized tests of reading accuracy or comprehension, is substantially below that expected given the person’s chronologic age, measured intelligence, and age-appropriate education.
B. The disturbance in criterion A significantly interferes with academic achievement or activities of daily living that require reading skills.
C. If a sensory deficit is present, the reading difficulties are in excess of those usually associated with it.
Mathematics Disorder DSM-IV Criteria
A. Mathematical ability, as measured by individually administered standardized tests, is substantially below that expected given the person’s chronologic age, measured intelligence, and age-appropriate education.
B. The disturbance in criterion A significantly interferes with academic achievement or activities of daily living that require mathematical ability.
C. If a sensory deficit is present, the difficulties in mathematical ability are in excess of those usually associated with it.
Disorder of Written Expression DSM-IV Criteria
A. Writing skills, as measured by individually administered standardized tests (or functional assessments of writing skills), are substantially below those expected given the person’s chronologic age, measured intelligence, and age-appropriate education.
B. The disturbance in criterion A significantly interferes with academic achievement or activities of daily living that require the composition of written texts (e.g., writing grammatically correct sentences and organized paragraphs).
C. If a sensory deficit is present, the difficulties in writing skills are in excess of those usually associated with it.
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
Reading disorders, mathematics disorders, and disorders of written expression can be specifically tested for in the school setting using individualized standardized tests. The child with such disorders will score substantially below what is expected based upon chronologic age and measured intelligence.
Many states will quantify this “gap” between where the child is performing and where the child is expected to perform, and will use this quantification as criteria that will make a child eligible for special education services. The learning disorder not otherwise specified has no written criteria, but the student is performing significantly below age and/or intelligence level in reading, mathematics, and written expression.
