Intellectual disability (ID), also known as general learning disability and mental retardation (MR), is a generalized neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning. It is defined by an IQ score below 70 in addition to deficits in two or more adaptive behaviours that affect every-day, general living. Once focused almost entirely on cognition, the definition now includes both a component relating to mental functioning and one relating to individuals’ functional skills in their environments. As a result of this focus on the person’s abilities in practice, a person with an unusually low IQ may not be considered to have intellectually disability. Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic intellectual disability, in which intellectual deficits appear without other abnormalities. Down syndrome and fragile X syndrome are examples of syndromic intellectual disabilities.
Intellectual disability affects about 2–3% of the general population. Seventy-five to ninety percent of the affected people have mild intellectual disability. Non-syndromic or idiopathic cases account for 30–50% of cases. About a quarter of cases are caused by a genetic disorder and about 5% of cases are inherited from parents. Cases of unknown cause affect about 95 million people as of 2013.
Children with mental challenge generally do everything late viz: they sit up late, crawl late, walk late and talk late.
Signs of Intellectual disability:
Intellectual disability (ID) begins during childhood and involves deficits in mental abilities, social skills, and core activities of daily living (ADLs) when compared to same-aged peers. There often are no physical signs of mild forms of ID, although there may be characteristic physical traits when it is associated with a genetic disorder (e.g. Down syndrome).
The level of impairment ranges in severity for each person. Some of the early signs can include:
Categories of Intellectual disability
Mild Intellectual disability – The range of 50 to 69 (standardized IQ test) is indicative of mild retardation. Understanding and use of language tend to be delayed to a varying degree and executive speech problems that interfere with the development of independence may persist into adult life.
Moderate Intellectual disability – The IQ is in the range of 35 to 49. Discrepant profiles of abilities are common in this group with some individuals achieving higher levels in visuospatial skills than in tasks dependent on language while others are markedly clumsy by enjoy social interaction and simple conversation. The level of development of language in variable: some of those affected can take part in simple conversations while others have only enough language to communicate their basic needs.
Severe Intellectual disability – The IQ is usually in the range of 20 to 34. In this category, most of the people suffer from a marked degree of motor impairment or other associated deficits indicating the presence of clinically significant damage to or mal development of the central nervous system.
Profound Intellectual disability – The IQ in this category estimated to be under 20. The ability to understand or comply with requests or instructions are severally limited. Most of such individuals are immobile or severally restricted in mobility, incontinent and capable at most of only very rudimentary forms of non-verbal communication. They possess little or no ability to care for their own basic needs and require constant help and supervision.