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Introduction
Learning Disorders are diagnosed when
the individual's achievement on individually administered, standardized
tests in reading, mathematics, or written expression is substantially
below that expected for age, schooling, and level of intelligence.
The learning problems significantly interfere with academic achievement
or activities of daily living that require reading, mathematical,
or writing skills. A variety of statistical approaches can be used
to establish that a discrepancy is significant. Substantially
below is usually defined as a discrepancy of more than 2 standard
deviations between achievement and IQ. A smaller discrepancy between
achievement and IQ (i.e., between 1 and 2 standard deviations) is
sometimes used, especially in cases where an individual's performance
on an IQ test may have been compromised by an associated disorder
in cognitive processing, a comorbid mental disorder or general medical
condition, or the individual's ethnic or cultural background. If a
sensory deficit is present, the learning difficulties must be in excess
of those usually associated with the deficit. Learning Disorders may
persist into adulthood.
Demoralization, low self-esteem, and deficits in social skills may
be associated with Learning Disorders. The school drop-out rate for
children or adolescents with Learning Disorders is reported at nearly
40% (or approximately 1.5 times the average). Adults with Learning
Disorders may have significant difficulties in employment or social
adjustment. Many individuals (10%-25%) with Conduct Disorder, Oppositional
Defiant Disorder, Attention-Deficit/Hyperactivity Disorder, Major
Depressive Disorder, or Dysthymic Disorder also have Learning Disorders.
There is evidence that developmental delays in language may occur
in association with Learning Disorders (particularly Reading Disorder),
although these delays may not be sufficiently severe to warrant the
separate diagnosis of a Communication Disorder. Learning Disorders
may also be associated with a higher rate of Developmental Coordination
Disorder.
There may be underlying abnormalities in cognitive
processing (e.g., deficits in visual perception, linguistic processes,
attention, or memory, or a combination of these) that often precede
or are associated with Learning Disorders. Standardized tests to measure
these processes are generally less reliable and valid than other psychoeducational
tests. Although genetic predisposition, perinatal injury, and various
neurological or other general medical conditions may be associated
with the development of Learning Disorders, the presence of such conditions
does not invariably predict an eventual Learning Disorder, and there
are many individuals with Learning Disorders who have no such history.
Learning Disorders are, however, frequently found in association with
a variety of general medical conditions (e.g., lead poisoning, fetal
alcohol syndrome, or fragile X syndrome).
2. Epidemiology
Estimates of the prevalence of Learning
Disorders range from 2% to 10% depending on the nature of ascertainment
and the definitions applied. Approximately 5% of students in public
schools in the United States are identified as having a Learning Disorder.
3. Etiology
Please view this where we discuss specific
Learning disorders (Reading Disorders, Mathematical Disorders, Written-Expression
Disorders)
4. References:
American Psychiatric Association: Diagnostic and Statistical
Manual of Mental Disorders, Fourth Edition, Text Revision. Washington,
DC, American Psychiatric Association, 2000.
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