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Disability: Definition, Types and Models

  • Synopsis: Definition of disability including types of disabilities and defining the meaning of the various models.

Definition: ICF

International Classification of Functioning, Disability and Health, also known as ICF, is a classification of the health components of functioning and disability. The World Health Assembly on May 22, 2001, approved the International Classification of Functioning, Disability and Health and its abbreviation of "ICF." This classification was first created in 1980 and then called the International Classification of Impairments, Disabilities, and Handicaps, or ICIDH by WHO to provide a unifying framework for classifying the health components of functioning and disability.

The ICF is structured around:

  • Body functions and structure.
  • Additional information on severity and environmental factors.
  • Activities (related to tasks and actions by an individual) and participation (involvement in a life situation).

Main Document

What is a Disability? A disability is defined as a condition or function judged to be significantly impaired relative to the usual standard of an individual or group. The term is used to refer to individual functioning, including physical impairment, sensory impairment, cognitive impairment, intellectual impairment mental illness, and various types of chronic disease.

Disability is conceptualized as being a multidimensional experience for the person involved. There may be effects on organs or body parts and there may be effects on a person's participation in areas of life. Correspondingly, three dimensions of disability are recognized in ICF: body structure and function (and impairment thereof), activity (and activity restrictions) and participation (and participation restrictions). The classification also recognizes the role of physical and social environmental factors in affecting disability outcomes.

Classifications of Disabilities

Types of disabilities include various physical and mental impairments that can hamper or reduce a person's ability to carry out his day to day activities. These impairments can be termed as disability of the person to do his or her day to day activities.

These impairments can be termed as disability of the person to do his day to day activities as previously. "Disability" can be broken down into a number of broad sub-categories, which include the following:

Mobility and Physical Impairments

This category of disability includes people with varying types of physical disabilities including:

  • Upper limb(s) disability
  • Lower limb(s) disability
  • Manual dexterity
  • Disability in co-ordination with different organs of the body

Disability in mobility can be either an in-born or acquired with age problem. It could also be the effect of a disease. People who have a broken bone also fall into this category of disability.

Spinal Cord Disability:

Spinal cord injury (SCI) can sometimes lead to lifelong disabilities. This kind of injury mostly occurs due to severe accidents. The injury can be either complete or incomplete. In an incomplete injury, the messages conveyed by the spinal cord is not completely lost. Whereas a complete injury results in a total dis-functioning of the sensory organs. In some cases spinal cord disability can be a birth defect.

Head Injuries - Brain Disability

A disability in the brain occurs due to a brain injury. The magnitude of the brain injury can range from mild, moderate and severe. There are two types of brain injuries:

  • Acquired Brain Injury (ABI)
  • Traumatic Brain Injury (TBI)

ABI is not a hereditary type defect but is the degeneration that occurs after birth.

The causes of such cases of injury are many and are mainly because of external forces applied to the body parts. TBI results in emotional dysfunctioning and behavioral disturbance.

Vision Disability

There are hundreds of thousands of people that suffer from minor to various serious vision disability or impairments. These injuries can also result into some serious problems or diseases like blindness and ocular trauma, to name a few. Some of the common vision impairment includes scratched cornea, scratches on the sclera, diabetes related eye conditions, dry eyes and corneal graft.

Hearing Disability

Hearing disabilities includes people that are completely or partially deaf, (Deaf is the politically correct term for a person with hearing impairment).

People who are partially deaf can often use hearing aids to assist their hearing. Deafness can be evident at birth or occur later in life from several biologic causes, for example Meningitis can damage the auditory nerve or the cochlea.

Deaf people use sign language as a means of communication. Hundreds of sign languages are in use around the world. In linguistic terms, sign languages are as rich and complex as any oral language, despite the common misconception that they are not "real languages".

Cognitive or Learning Disabilities

Cognitive Disabilities are kind of impairment present in people who are suffering from dyslexia and various other learning difficulties and includes speech disorders.

Psychological Disorders

Affective Disorders:

Disorders of mood or feeling states either short or long term.

Mental Health Impairment is the term used to describe people who have experienced psychiatric problems or illness such as:

  • Personality Disorders - Defined as deeply inadequate patterns of behavior and thought of sufficient severity to cause significant impairment to day-to-day activities.
  • Schizophrenia: A mental disorder characterized by disturbances of thinking, mood, and behavior.

Invisible Disabilities

Invisible Disabilities are disabilities that are not immediately apparent to others. It is estimated that 10% of people in the U.S. have a medical condition considered a type of invisible disability.

Quick Facts: Disability Classification

Disabilities can affect people in different ways, even when one person has the same type of disability as another person. Some disabilities may be hidden, known as invisible disability. There are many types of disabilities, such as those that affect a person's:

  • Vision
  • Hearing
  • Thinking
  • Learning
  • Movement
  • Mental health
  • Remembering
  • Communicating
  • Social relationships

The World Health Organization (WHO) published the International Classification of Functioning, Disability and Health (ICF) in 2001 that covers;

  • Activity
  • Participation
  • Body Structures
  • Body Functions
  • Personal Factors
  • Health Conditions
  • Activity Limitations
  • Functional Limitations
  • Environmental Factors
  • Participation Restrictions

Statistics: Prevalence

In the year 2011, an estimated 8.1 percent (plus or minus 0.2 percentage points) of civilian non-institutionalized, men and women, aged 18-64 in the United States reported a work limitation.

In other words, 15,479,000 out of 191,096,000 (or about one in 12) civilian non-institutionalized, men and women, aged 18-64 in the United States reported a work limitation.

The estimated percentage above is based on a sample of 124,163 persons who participated in the Current Population Survey (CPS).

(Nazarov, Z, Lee, C. G. (2012). Disability Statistics from the Current Population Survey (CPS). Ithaca, NY: Cornell University Rehabilitation Research and Training Center on Disability Demographics and Statistics (StatsRRTC). Retrieved March 2, 2015 from

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