Intellectual disability

The term mental handicap (also "mental retardation" and "mental retardation") refers to a persistent state of clearly below-average cognitive abilities of a person as well as the associated restrictions of his emotional life and behaviour as well as motor abilities, if any.

However, a clear and generally accepted definition is difficult: medically oriented definitions speak of a "reduction or lowering of the maximum attainable intelligence". The International Statistical Classification of Diseases and Related Health Problems (ICD-10) also refers to this phenomenon as "intelligence impairment" (F70-79). According to this, an intellectual disability can be understood - purely in terms of intelligence - as an increase and extension of a learning disability. Other definitions, on the other hand, focus more on the interaction of the affected person with his or her environment instead of intelligence.

The term must be distinguished from similar phenomena. Age- or disease-related loss of previously mastered abilities (and thus also of intelligence) is referred to as dementia. In the case of permanent impairments due to mental or neurological illnesses, which primarily present themselves in the form of impaired thinking with (largely) retained intelligence, one speaks of a mental disability. In general, mental, physical and intellectual disabilities can occur independently of each other or in combination.

Diagnosis

Intelligence test

A diagnosis of intellectual disability often refers to the measurement of a significant reduction in intelligence using standardized intelligence tests. An intelligence quotient (IQ) in the range of 70 to 85 is below average; in this case one speaks of a learning disability. An IQ below 70 then conditions the diagnosis of mental retardation. A further subdivision of this range is considered obsolete by some authors, since there are no measurement procedures that yield valid and reliable results with the necessary discriminatory power. Even today, the attribution of an intellectual disability by intelligence measurement is highly controversial. IQ tests are carried out regularly, but they are not interpreted as the sole value. In some cases, the performance of an intelligence test is not possible due to a physical disability or a behavioural disorder.

Other diagnostic procedures

The individual case description in the context of a systemic analysis of the human-environment conditions is common today: Is independent eating and drinking, dressing possible? In the area of the lowest intelligence performances, which occur in the case of severe disease patterns, adhesions in the brain or parts of the brain destroyed due to war, classical conditioning to certain stimuli was used diagnostically in the past: Can the patient be conditioned with positive stimuli or regular habits (sweets, meal times), or can only aversive stimuli still be associated with an avoidance response. Clinically, the diagnosis was used primarily in the sense of a borderline indication (e.g., borderline deformed), although scaling with point values was also possible. The indications therefore lost their value as a distribution function in the lower range and were a purely diagnostic class.

Differential Diagnosis

Some illnesses or disabilities superficially resemble mental retardation, but are to be distinguished from it in the sense of a differential diagnosis. These are, for example, early childhood autism, psycho-social deprivation (also deprivation syndrome or hospitalism), dementia or brain-organic diseases. Also the so-called pseudodebility (also: pseudodementia, in adults Ganser syndrome) is to be distinguished from mental retardation, because here the cognitive impairment is a conversion symptom. The main distinctions are that the intellectual disability is present from the beginning, that there are no delusional symptoms and that the social behaviour is not autistic.