The evolution of the concept of Intellectual Disability

After the discovery and establishment of the psychometric and factorial methodology in the study of intelligence at the beginning of the last century by Alfred Binet and Simon (1905) and later, Terman (1916) and Weschler in the 1930s, the IQ became the central factor in the evaluation of intellectual capacity.

However, the most recent proposal of the American Association on Mental Retardation (AAMR) of 1992 seems to overcome some of the drawbacks that the first formula had associated.

• Related article: “Types of intelligence tests”

Intellectual Disability as a Neurodevelopmental Disorder

A Neurodevelopmental Disorder (or Neurodevelopmental Disorders, according to the DSM-V) is understood as any disease related to an alteration during the maturation process of the nervous system that affects inadequate functioning at the level of behavior, thought, movement, learning, perceptive-sensory capacity and other complex mental functions.

The set of manifestations that can occur as a consequence are of a very considerable variety, since attention must be paid to both the location of the dysfunction, influencing environmental factors as well as the moment of development in which said dysfunction occurs disturbance.

Neuroscience is the discipline that deals with the study and research of ODDs, as well as other neurodegenerative disorders, static lesion disorders, and psychiatric disorders. In certain cases, the same pathology can be considered within more than one of these categories, which differ from each other around two dimensions: time (development-decline) and phenomenology (cognitive-emotional).

Her CARACTERISTICS

Among the characteristics attributed to ODDs, there is the difficulty of distinguishing whether the origin of the external manifestation of the underlying symptomatology is derived from an ODD or from a type of normative functioning, such as the case of distractibility (which it may be due to an affectation of the structures that regulate attentional capacity or it may be a marked personality trait, simply).

So, no known biomarkers (neuroimaging tests or analysis) associated from which an ODD can be diagnosed unequivocally. The evaluator's subjectivity therefore plays a significant role in the diagnosis of the case.

In second place, ODDs have a very high comorbidity with other pathologies, a fact that on certain occasions can make it difficult to accurately diagnose the case, since all the labels present must be detected. On the other hand, the delimitation between the symptoms attributable to one disorder and another is also complex, since many of them they share common criteria (for example, the difficulty in social relationships in a case of autism and mental disorder). language).

• Related article: "Intellectual and Developmental Disability"

Types of Neurodevelopmental Disorders

In a generic way, the TND can be classified into three main categories according to the criteria:

Whether or not a specific cause is identified

In this case genetic influence is a significant causative factor.. The most widely used classificatory manuals (DSM and ICD) include communication disorders, learning disorders, hyperactivity, and autism spectrum. In the case of conduct disorders, schizophrenic disorders and Tourette's disorder, the beginning age difference for each of them, so depending on the case they can also be included in this first category.

Genetic alterations linked to a structural alteration

Easier to define, since phenotypic deviations are clearly identifiable (deletion, duplication, translocation, chromosomal disomies or trisomies, etc.), as in the case of Williams Syndrome.

TND linked to a known environmental cause

Its influence is usually considered in interaction with genetic factors, e.g. fetal poisoning due to maternal alcohol consumption or pathologies derived from the action of valproic acid.

The traditional conceptualization of Intellectual Disability

As indicated at the beginning of these lines, the last century was marked by the rise of psychometric scales on the assessment and quantification of the level of intelligence in the being human.

Thus, the only determining reference was taken distinction between the classificatory levels of Intellectual Disability based on the individual's Intellectual Quotient (IQ). Let's see a more detailed description of each of these categories:

Mild Mental Retardation

Understands an IQ between 55 and 70 and presents a proportion of 85% of all cases. Being the least significant level in severity, it is difficult to distinguish in the first years of life. In this case, the social and communication skills or the capacity for autonomy are rather well preserved, although they require some type of supervision and follow-up. There are no great difficulties in achieving the development of a satisfactory life.

Moderate Mental Retardation

A second level of greater severity with a prevalence of 10% is that of Moderate Mental Retardation, to which an IQ between 40 and 55 is attributed. In this case the level of social and communication development is lower and they must be supervised during adult working and personal life, although they can still adapt to community life on most occasions.

Severe Mental Retardation

Severe Mental Retardation is associated with an IQ between 25 and 40 and occurs in 3-4% of all cases. His linguistic ability is very limited but are capable of acquiring elementary self-care habits. They need a considerable level of support and help to adapt to community life.

Profound Mental Retardation

Profound Mental Retardation is characterized by an IQ of less than 25 and is present in between 1 and 2% of the population with MR. At this level there are clear and severe motor, sensory and cognitive difficulties. They require constant and permanent supervision and a highly structured environment in which they interact.

• Related article: "Types of intellectual disability (and characteristics)"

Descriptive dimensions of intellectual functioning

The most recent proposal of the American Association on Mental Retardation (AAMR) implies a drastic change in the conception of intellectual disability and emphasizes giving the definition of Mental Retardation a somewhat more positive and optimistic connotation in terms of valuing mainly the abilities and potential of the individual with intellectual dysfunction, as well as the support he needs to achieve said goals.

Thus, the AAMR definition proposal on Mental Retardation explains it as a series of substantial limitations in the intellectual functioning, which is significantly lower than average and which manifests itself before the age of 18 age.

Assessment dimensions of Mental Retardation

Specifically, the large dimensions proposed by the AAMR on which to assess at a functional level the abilities available to the child and that can be reached with a global multidisciplinary intervention:

• Intellectual skills.
• Adaptive behavior at a conceptual, social and practical level.
• Participation, interactions and social roles.
• Physical and mental health, etiology of possible alterations.
• Social context, related to the environment, culture and opportunities to access this type of stimulation.

Unlike the previous ones, in this proposal there is an emphasis on the social context and on determining what resources are required to guarantee the greatest number of learning, autonomy and well-being of the child in his day to day, instead of taking as a central factor the deficits and difficulties that the child presents little.

This brings various advantages both at the level of the reduction of negative labeling that is usually associated with individuals who present this type of deficit, since the definition grants a main role to the potentialities and capacities to be developed by the boy. Furthermore, this new definition s****e is more oriented towards determining the type of intervention that will be necessary for the specific case to obtain the highest level of development possible (environmental, social, personal and intellectual adaptations).

In this new conception, the following postulates are assumed: the consideration of cultural and linguistic, communicative and behavioral diversity; the need for the existence of individualized supports at the community level; the coexistence of potentialities in other adaptive areas or personal capacities; the assumption of improvement in the person's functioning by providing appropriate supports over a sustained period of time.

In short, it seems that the most recent definition of Mental Retardation aims to provide a more practical, positive and adaptive perspective that will facilitate greater integration of the individual both personally and socially, enabling greater development by emphasizing their qualities rather than their difficulties.