Developmental disability
Synonyms and keywords: Cognitive disability; developmental delay; developmental delays; intellectual disability; global development delay; learning disability

# Overview
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.

# Classification Scheme
Developmental disabilities are usually classified as severe, profound, moderate or mild, as assessed by the individual's need for supports, which may be lifelong. This use of the term is synonymous with the use of the term learning disability in the United Kingdom (however not in the United States) and intellectual disability in Australia, Europe, Canada and elsewhere. Cognitive disability is also used synonymously in some jurisdictions.

## Global Developmental Delay

# Causes
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:
- Brain injury or infection before, during or after birth
- Growth or nutrition problems
- Abnormalities of chromosomes and genes
- Babies born long before the expected birth date - also called extreme prematurity
- Poor diet and health care
- Drug misuse during pregnancy, including excessive alcohol intake and smoking.
- Child abuse can also have a severe effect on the development of a child, specifically the socio-emotional development.
- 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.

# Epidemiology and Demographics
Developmental disabilities affect between 1 and 2% of the population in most western countries, although many government sources acknowledge that statistics are flawed in this area. The worldwide proportion of people with developmental disabilities is believed to be approximately 1.4%. It is twice as common in males as in females, and some researchers have found that the prevalence of mild developmental disabilities is likely to be higher in areas of poverty and deprivation, and among people of certain ethnicities.

# Natural History, Complications, and Prognosis

## Physical health issues
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. 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, and some specific diagnoses (such as Freeman-Sheldon syndrome) do not impact on life expectancy.

## Mental health issues (dual diagnoses)
Mental health issues, and psychiatric illnesses, are more likely to occur in people with developmental disabilities than in the general population. A number of factors are attributed to the high incidence rate of dual diagnoses:
- the high likelihood of encountering traumatic events throughout their lifetime (such as abandonment by loved ones, abuse, bullying and harassment)
- the social restrictions placed upon people with developmental disabilities (such as lack of education, poverty, limited employment opportunities, limited opportunities for fulfilling relationships, boredom)
- 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..

## Abuse and vulnerability
Abuse is a significant issue for people with developmental disabilities, and as a group they are regarded as vulnerable people in most jurisdictions. Common types of abuse include:
- Physical abuse (withholding food, hitting, punching, pushing, etc.)
- Neglect (withholding help when required, e.g., assistance with personal hygiene)
- Sexual abuse
- Psychological or emotional abuse (verbal abuse, shaming and belittling)
- Constraint and restrictive practices (turning off an electric wheelchair so a person cannot move)
- Financial abuse (charging unnecessary fees, holding onto pensions, wages, etc.)
- Legal or civil abuse (restricted access to services)
- Systemic abuse (denied access to an appropriate service due to perceived support needs)
- Passive neglect (a caregivers 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).

## Challenging behaviour
Some people with developmental disabilities exhibit challenging behaviour, defined as "culturally abnormal behaviour(s) of such intensity, frequency or duration that the physical safety of the person or others is placed in serious jeopardy, or behaviour which is likely to seriously limit or deny access to the use of ordinary community facilities". Common types of challenging behaviour include self-injurious behaviour (such as hitting, headbutting, biting), aggressive behaviour (such as hitting others, screaming, spitting, kicking), inappropriate sexualised behaviour (such as public masturbation or groping), behaviour directed at property (such as throwing objects and stealing) and stereotyped behaviours (such as repetitive rocking, echolalia or elective incontinence).
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 (boredom, seeking social interaction, the need for an element of control, lack of knowledge of community norms, insensitivity of staff and services to the person's wishes and needs), environmental (physical aspects such as noise and lighting, or gaining access to preferred objects or activities), psychological (feeling excluded, lonely, devalued, labelled, disempowered, living up to people's negative expectations) 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.
Experience and research suggests that what professionals call 'challenging behaviour' is often a reaction to the challenging environments that services create around people with developmental disabilities, and a method of communicating dissatisfaction with the failure of services to listen for what kind of life makes most sense to the person, especially where services deliver lifestyles and ways of working that are centred on what suits the service and it's staff rather than what suits the person.

# Societal attitudes towards developmental disabilities
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, led 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", 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. Wolfensberger 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.
From the 1960's to the present, most states have moved towards the elimination of segregated institutions.  Along with the work Wolfensberger and others including Gunnar and Rosemary Dybwad, a number of scandalous revelations around the horrific conditions within state institutions created public outrage led to change to a more community-based method of providing services.
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, although the debate over whether or not to close instiutions persists in some states, including Massachusetts.
It could be argued that we still have a very long way to go before people with such disabilities are seen as full citizens of society. Person Centred Planning and Person Centred Approaches are seen as methods of addressing the continued labelling and exclusion of socially devalued people, such as people with a developmental disability label, encouraging a focus on the person as someone with capacities and gifts, as well as support needs.

# Diagnosis
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

# Treatment
Today, support services are provided by government agencies, non-governmental organizations 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 training
Education and training opportunities for people with developmental disabilities have expanded greatly in recent times, with many governments mandating universal access to educational facilities, and more students moving out of special schools and into mainstream classrooms with support.
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 support
Many people with developmental disabilities live in the general community, either with family members, or in their own homes (that they rent or own, living alone or with flatmates). At-home and community supports range from one-to-one assistance from a support worker with identified aspects of daily living (such as budgeting, shopping or paying bills) to full 24-hour support (including assistance with household tasks, such as cooking and cleaning, and personal care such as showering, dressing and the administration of medication). The need for full 24-hour support is usually associated with difficulties recognising safety issues (such as responding to a fire or using a telephone) or for people with potentially dangerous medical conditions (such as asthma or diabetes) who are unable to manage their conditions without assistance.
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 individual with a developmental disability, 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 accommodation
Some people with developmental disabilities live in residential accommodation (also known as group homes) with other people with similar assessed needs. These homes are usually staffed around the clock, and usually house between 3 and 15 residents. The prevalence of this type of support is gradually decreasing, however, as residential accommodation is replaced by at-home and community support, which can offer increased choice and self-determination for individuals. Some U.S. states still provide institutional care, such as the Texas State Schools.

## Employment support
Employment support usually consists of two types of support:
- Support to access or participate in integrated employment, in a workplace in the general community. This may include specific programs to increase the skills needed for successful employment (work preparation), one-to-one or small group support for on-the-job training, or one-to-one or small group support after a transition period (such as advocacy when dealing with an employer or a bullying colleague, or assistance to complete an application for a promotion).
- 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 services
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).
Traditional day centres were based on the principles of occupational therapy, and were created as respite for family members caring for their loved ones with disabilities. This is slowly changing, however, as programs offered become more skills-based and focused on increasing independence.

## Advocacy
Advocacy is a burgeoning support field for people with developmental disabilities. Advocacy groups now exist in most jurisdictions, working collaboratively with people with disabilities for systemic change (such as changes in policy and legislation) and for changes for individuals (such as claiming welfare benefits or when responding to abuse). Most advocacy groups also work to support people, throughout the world, to increase their capacity for self-advocacy, teaching the skills necessary for people to advocate for their own needs.

## Other types of support
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
- short-stay respite services (for people who live with family members or other unpaid carers)
- transport services, such as dial-a-ride or free bus passes
- specialist behaviour support services, such as high-security services for people with high-level, high-risk challenging behaviours
- specialist relationships and sex education services