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Developmental disabilities

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Developmental disabilities
ICD-9 783.4
OMIM [10]
DiseasesDB [11]
MedlinePlus [12]
eMedicine /
MeSH {{{MeshNumber}}}

Developmental disability is a term used to describe life-long disabilities attributable to mental and/or physical or combination of mental and physical impairments, manifested prior to age twenty-two. The term is used most commonly in the United States to refer to disabilities affecting daily functioning in three or more of the following areas:

  • capacity for independent living
  • economic self-sufficiency
  • learning
  • mobility
  • receptive and expressive language
  • self-care
  • self-direction

Usually people with mental retardation, cerebral palsy, autism spectrum disorder, various genetic and chromosomal disorders such as Down syndrome and Fragile X syndrome, and Fetal Alcohol Spectrum Disorder are described as having developmental disabilities. This use of the term is synonymous with the use of the term learning disability in the United Kingdom and intellectual disability in Australia, Europe, Canada and elsewhere. Cognitive disability is also used synonymously in some jurisdictions.

Developmental disabilities are usually classified as severe, profound, moderate or mild, as assessed by the individual's need for supports, which may be lifelong.

Causes of developmental disabilitiesEdit

There are many social, environmental and physical causes of developmental disabilities, although for some a definitive cause may never be determined. Common factors causing developmental disabilities include:


About 75–80 percent of mental handicaps are familial, and 20–25 percent are due to biological problems which are not heritable, such as chromosomal abnormalities and brain damage.[3] Mental disability is a symptom of several hundred single-gene disorders and many chromosomal abnormalities, including small deletions. Based on twin studies, mild mental disability was shown to be heritable, while moderate to severe mental disability was not. That is, the relatives of the moderate to severely mentally handicapped had IQs in the normal range, whereas the families of the mildly mentally handicapped had IQs in the lower range[How to reference and link to summary or text].

The rate of mental retardation is higher among males than females, according to a 1991 U.S. Centers for Disease Control and Prevention (CDC) study.[4] This is aggravated by the fact that males, unlike females, do not have a spare X chromosome to offset chromosomal defects.

Associated issuesEdit

Physical health issuesEdit

There are many physical health factors associated with developmental disabilities. For some specific syndromes and diagnoses, these are inherent (such as poor heart function in people with Down syndrome); however lack of access to health services and lack of understanding by medical professionals is also a major contributing factor. People with severe communication difficulties find it difficult to articulate their health needs, and without adequate support and education might not recognise ill health. Epilepsy, sensory problems (such as poor vision and hearing), obesity and poor dental health are over-represented in this population.[5] Life expectancy among people with developmental disabilities as a group is estimated at 20 years below average, although this is increasing with advancements in adaptive and medical technologies, and as people are leading healthier, more fulfilling lives,[6] and some specific diagnoses (such as Freeman-Sheldon syndrome) do not impact on life expectancy.

Mental health issues (dual diagnoses)Edit


  • biological factors (such as brain injury, epilepsy, illicit and prescribed drug and alcohol misuse)
  • developmental factors (such as lack of understanding of social norms and appropriate behaviour, inability of those around to allow/ understand expressions of grief and other human emotions)

These problems are exacerbated by difficulties in diagnosis of mental health issues, and in appropriate treatment and medication, as for physical health issues.[7][8]

Abuse and vulnerabilityEdit


  • Sexual abuse
  • Legal or civil abuse (restricted access to services)
  • Passive neglect (a caregiver’s failure to provide adequate food, shelter)

Lack of education, lack of self-esteem and self-advocacy skills, lack of understanding of social norms and appropriate behaviour and communication difficulties are strong contributing factors to the high incidence of abuse among this population.

In addition to abuse from people in positions of power, peer abuse is recognised as a significant, if misunderstood, problem. Rates of criminal offending among people with developmental disabilities are also disproportionately high, and it is widely acknowledged that criminal justice systems throughout the world are ill-equipped for the needs of people with developmental disabilities (as both perpetrators and victims of crime)[9][10][11].

Challenging behaviourEdit

See main article: Challenging behaviour


Challenging behaviour in people with developmental disabilities may be caused by a number of factors, including biological (pain, medication, the need for sensory stimulation), social (attention-seeking, the need for control, lack of knowledge of community norms), environmental (physical aspects such as noise and lighting, or gaining access to preferred objects or activities) or simply a means of communication. A lot of the time, challenging behaviour is learned and brings rewards, and it is very often possible to teach people new behaviours to achieve the same aims.

Societal attitudes towards developmental disabilitiesEdit

Throughout history, people with developmental disabilities have been viewed as incapable and child-like in their capacity for decision-making and development. Until the Enlightenment in Europe, care and asylum was provided by families and the church (in monasteries and other religious communities), focusing on the provision of basic physical needs such as food, shelter and clothing. Stereotypes such as the dimwitted yokel, and potentially harmful characterisations (such as demonic possession for people with epilepsy) were prominent in social attitudes of the time.

The movement towards individualism in the 18th and 19th centuries, and the opportunities afforded by the Industrial Revolution, lead to housing and care using the asylum model. People were placed by, or removed from, their families (usually in infancy) and housed in large institutions (of up to 3,000 people, although some institutions were home to many more, such as the Philadelphia State Hospital in Pennsylvania which housed 7,000 people through the 1960s), many of which were self-sufficient through the labour of the residents.

Some of these institutions provided a very basic level of education (such as differentiation between colours and basic word recognition and numeracy), but most continued to focus solely on the provision of basic needs. Conditions in such institutions varied widely, but the support provided was generally non-individualised, with aberrant behaviour and low levels of economic productivity regarded as a burden to society. Heavy tranquilisation and assembly line methods of support (such as 'birdfeeding' and cattle herding) were the norm, and the medical model of disability prevailed. Services were provided based on the relative ease to the provider, not based on the human needs of the individual.

This segregation of people with developmental disabilities wasn't widely questioned by academics or policy-makers until the 1969 publication of Wolf Wolfensberger's seminal work "The Origin and Nature of Our Institutional Models",[13] drawing on some of the ideas proposed by SG Howe a hundred years earlier. This book posited that society characterises people with disabilities as deviant, sub-human and burdens of charity, resulting in the adoption of that 'deviant' role. He argued that this dehumanisation, and the segregated institutions that result from it, ignored the potential productive contributions that all people can make to society. He pushed for a shift in policy and practice that recognised the human needs of "retardates" and provided the same basic human rights as for the rest of the population.

The publication of this book may be regarded as the first move towards the widespread adoption of the social model of disability in regard to these types of disabilities, and was the impetus for the development of government strategies for desegregation. Successful lawsuits against governments and an increasing awareness of human rights and self-advocacy also contributed to this process, resulting in the passing in the US of the Civil Rights of Institutionalized Persons Act in 1980.

By the mid-1970s, most governments had committed to de-institutionalisation, and had started preparing for the wholesale movement of people into the general community, in line with the principles of normalization. In most countries, this was essentially complete by the late 1990s.

Services and supportEdit

Today, support services are provided by government agencies, non-governmental organisations and by private sector providers. Support services address most aspects of life for people with developmental disabilities, and are usually theoretically based in community inclusion, using concepts such as social role valorization and increased self-determination (using models such as Person Centred Planning). Support services are funded through government block funding (paid directly to service providers by the government), through individualised funding packages (paid directly to the individual by the government, specifically for the purchase of services) or privately by the individual (although they may receive certain subsidies or discounts, paid by the government).

Education and trainingEdit

See main article: Special education


Post-secondary education and vocational training is also increasing for people with these types of disabilities, although many programs offer only segregated "access" courses in areas such as literacy, numeracy and other basic skills. Legislation (such as the UK's Disability Discrimination Act 1995) requires educational institutions and training providers to make 'reasonable adjustments' to curriculum and teaching methods in order to accommodate the learning needs of students with disabilities, wherever possible.

At-home and community supportEdit


In the United States a support worker is known as a Direct Support Professional (DSP). The DSP works in assisting the individual with their ADLs and also acts as an advocate for the developmentally disabled individual, in communicating their needs, self expression and goals.

Supports of this type also include assistance to identify and undertake new hobbies or to access community services (such as education), learning appropriate behaviour or recognition of community norms, or with relationships and expanding circles of friends. Most programs offering at-home and community support are designed with the goal of increasing the individual's independence, although it is recognised that people with more severe disabilities may never be able to achieve full independence in some areas of daily life.

Residential accommodationEdit


Employment supportEdit

Employment support usually consists of two types of support:

  • The provision of specific employment opportunities within segregated business services. Although these are designed as 'transitional' services (teaching work skills needed to move into integrated employment), many people remain in such services for the duration of their working life. The types of work performed in business services include mailing and packaging services, cleaning, gardening and landscaping, timberwork, metal fabrication, farming and sewing.

Workers with developmental disabilities have historically been paid less for their labour than those in the general workforce, although this is gradually changing with government initiatives, the enforcement of anti-discrimination legislation and changes in perceptions of capability in the general community.

Day servicesEdit

Non-vocational day services are usually known as day centres, and are traditionally segregated services offering training in life skills (such as meal preparation and basic literacy), centre-based activities (such as craft, games and music classes) and external activities (such as day trips). Some more progressive day centres also support people to access vocational training opportunities (such as college courses), and offer individualised outreach services (planning and undertaking activities with the individual, with support offered one-to-one or in small groups).




Other types of supportEdit

Other types of support for people with developmental disabilities may include:

  • therapeutic services, such as speech therapy, massage, aromatherapy, or drama or music therapy
  • supported holidays
  • specialist behaviour support services, such as high-security services for people with high-level, high-risk challenging behaviours
  • specialist relationships and sex education services

Notes Edit

  1. [1]
  2. Valuing People, p. 16
  3. Steve Sailer. IQ Defenders Feel Vindicated by Supreme Court. UPI.
  4. Coleen A. Boyle, Prevalence of Selected Developmental Disabilities in Children 3-10 Years of Age: the Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1991. National Center for Environmental Health, Division of Birth Defects and Developmental Disabilities.
  5. [2]
  6. [3]
  7. [4]
  8. [5]
  9. [6]
  10. [7]
  11. [8]
  13. [9]
  14. Texas Department of Aging and Disability Services



See alsoEdit

Further readingEdit

External linksEdit


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