An impairment is a health condition involving a loss or significant alteration of the body’s structure or function. This concept focuses exclusively on the internal state of the person’s body or mind, representing a deviation from a generally accepted biomedical norm. It is a foundational term used across medicine, public health, and social policy to describe a problem at the level of the body itself.
The Functional Definition of Impairment
Impairment is formally defined as a problem in body function or structure, representing a significant deviation or loss. This relates directly to the physiological functions of body systems (including psychological functions) or anatomical parts (such as organs and limbs). A structural impairment might be the loss of a limb, while a functional impairment could be chronic pain or reduced range of motion. These problems manifest from a health condition, such as a disease, disorder, or injury, at the body level.
The international classification system views impairment as the underlying medical or anatomical deviation. For example, reduced visual acuity due to retinal damage is an impairment of eye function. Difficulty in memory retention following a traumatic brain injury is an impairment of a psychological function within the central nervous system. This perspective focuses on the specific biological or psychological problem before considering its effect on daily life.
Distinguishing Impairment from Disability and Handicap
The terms impairment, disability, and handicap describe distinct, yet related, levels of human experience. Impairment is the problem with the body function or structure itself, such as hearing loss or a missing digit. Disability, or activity limitation, is the resulting difficulty an individual has in executing specific tasks, such as an inability to hear a conversation or a struggle to grip small objects. Handicap, or participation restriction, refers to the disadvantage that limits or prevents the fulfillment of a normal social role, often due to environmental barriers.
A person with a spinal cord injury has an impairment in nerve function, resulting in the disability of being unable to walk. This disability becomes a handicap if the individual cannot access a public building due to a lack of a ramp, preventing community participation. An impairment does not automatically lead to a handicap; if the environment is fully accessible, the participation restriction can be minimized or eliminated. The distinction highlights that a handicap is often a social disadvantage resulting from the interaction between functional limitation and an unsupportive environment.
Primary Categories of Impairment
Impairments are broadly categorized based on the type of body function or structure affected: physical, sensory, and cognitive/psychiatric. Physical or structural impairments affect anatomical parts or functions related to movement and dexterity. Examples include paralysis from a stroke, chronic joint inflammation from severe arthritis, or the loss of a limb.
Sensory impairments involve the functions of the five senses, affecting how an individual perceives the world. This category includes significant reduction in visual acuity (visual impairment) or hearing loss that affects sound processing.
Cognitive and psychiatric impairments involve mental functions, such as learning, memory, attention, and emotional regulation. Conditions like severe difficulty focusing attention or a persistent decline in memory function are classified here.
Medical and Functional Assessment
The identification and documentation of an impairment rely on a systematic process of medical and functional assessment. This process begins with a physician or specialist (e.g., a neurologist or audiologist) who uses diagnostic tools to pinpoint the nature and extent of the structural or functional loss. Medical assessment often involves objective testing to quantify the degree of deviation from the norm, such as using an audiogram to measure hearing loss across different frequencies.
Functional assessments complement the medical diagnosis by measuring the impairment’s impact on specific abilities. Standardized tests are used to quantify the loss, which is necessary for treatment planning and documentation. For example, the Mini-Mental State Examination (MMSE) or the Montreal Cognitive Assessment (MoCA) are widely used to screen for cognitive decline in areas like orientation and recall. Performance-based assessments, such as the Timed Up and Go test, can measure a person’s balance and mobility.