Learning Disorders

Samuel Kirk coined the term learning disabilities in 1963. In the broadest sense, all problems in learning may be considered learning disorders, but the term learning disabilities is reserved for specific problems in learning as noted in the Individuals with Disabilities Education Improvement Act. Learning disabilities involve a wide range of problems with oral and written language, reading, and mathematics. This can include problems with speech, reading, writing, spelling, mathematical calculations, and comprehension, [Page 1000]thinking, and reasoning. The common characteristic of learning disabilities is that the individual displays academic underachievement in the affected domain. Not all children who underachieve have learning disabilities. Underachievement may be due to behavioral, emotional, motivational, intellectual, or other factors. Furthermore, learning disabilities may coexist with other developmental disorders, such as attention disorders.

Learning disabilities affect some combination of getting information into the brain, making sense of the information, and retaining and retrieving the information. Thus, acquisition and organization of information can be affected as well as how the information is comprehended and remembered. Learning disabilities may be primarily verbal or they may be nonverbal. One or more of the processes related to perceiving, thinking, remembering, or learning is affected.

Learning disabilities are considered to be neurobiological disorders in which how a person's brain functions or is structured affects one or more of the basic processes involved with oral or written language or with mathematics. Current technological advances in neuropsychological research methods (i.e., positron emission tomography (PET), magnetic source imaging (MSI) and magnetic resonance spectroscopy (MRS) are beginning to yield insights into the biology behind the disabilities. For example, functional magnetic resonance imaging (MRI) studies have revealed that those with reading problems show less activity in left posterior brain regions and greater reliance on Broca's area. As disorders of the central nervous system, many potential causal factors have been implicated including heredity and pre- and postnatal factors. While there are familial tendencies to learning disabilities, the disorder may manifest differently in different generations: for example, a parent may have a writing disorder while the child has a reading problem. This suggests a subtle brain dysfunction may be inherited as opposed to direct inheritance of a specific disorder. As the brain develops during pregnancy, disruptions caused by illness, alcohol, or smoking may cause errors that later manifest as learning disabilities. Head injuries or environmental toxins have been implicated as possible postnatal factors.

It is estimated that 5 to 15 percent of North American children have a learning disability with higher prevalence rates for boys than for girls; however, this may be due to differences in referral patterns. Learning disabilities are developmental in nature and are typically diagnosed during childhood; occasionally, they can first be identified in adults, although they would have been present earlier. Most children will have a documented history of learning problems in school. Children with significant delays in skill development are often first suspected as having possible learning problems. A child who suddenly develops learning problems that were not present earlier more likely has a behavioral or emotional disorder than a learning disorder.

...