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4. PREVALENCE AND ETIOLOGY OF LEARNING DISABILITIES Approximately 5% of all public school students are identified as having a learning disability. The prevalence of learning disability identification has increased dramatically in the past 20 years. Heward states that as much as 47% of all school-age children with disabilities have a learning disability. Some professional believe that the increasing number of students with LD is partially a result of overidentification and misdiagnosis of low-achieving students. The “real” prevalence of LD is subject to much dispute because of the lack of an agreed-upon definition of LD with objective identification criteria. There is a whole range of theories about possible causes of learning disabilities. First group of theories mentions impairment in perception, speech and motor skills. Second group takes neurological point of view and finds the cause in brain damage or dysfunction or improper function of perception organs (e.g. eyes). Neurological origin applies especially to more serious learning difficulties. Third group talks about impaired communication of a child and its environment. This theory has been used especially in psychiatry. Another possible cause of LD are environmental factors, especially living conditions and quality and frequency of instruction. This theory is supported by the evidence that LD have tendency to run in families. Finally, we should mention division of causes based on Kučera´s research: (1) minimal brain damage (50%), (2) heredity (20%), (3) heredity and brain damage (15%), (4) neurotic or unspecified causes (15%). All the above mentioned causes frequently combine and result in a child having problems in more areas. |