General Theory of Rehabilitation

There is no published explicit theory of biomedical healthcare nor one for rehabilitation. The implicit biomedical theory is not functioning well and particularly disadvantages rehabilitation, which is without any theory. On October 27th 2023, I published a General Theory of Rehabilitation. I hope it will facilitate a fuller understanding of rehabilitation by all parties: patients, families, healthcare professionals, policymakers, politicians, commissioners, rehabilitation teams, and the public. It should then lead to more equitable resource allocation, the formation of rehabilitation networks, as recommended by the Community Rehabilitation Alliance, new avenues of research, a change in acute hospitals with expert rehabilitation being available and all buildings and cultures enabling early intervention, and a better outcome for all patients. It is a simple theory that anyone can understand. It will need improvement, and more detailed theories about aspects of rehabilitation should easily be compatible. This page outlines the theory. Other pages will expand the discussion on different aspects.

Table of Contents

Links to additional pages


Dr John Stanley Coulter (born 1885) was one of the founding fathers of rehabilitation in the United States. He died in 1949. In 2007, John Whyte gave the 57th John Stanley Coulter Memorial Lecture, entitled “A Grand Unified Theory of Rehabilitation (We Wish!).“ He stated, “It is self-evident that no single theoretical framework can account for changes in organ structure and function, changes in activity performance, and changes in the social and physical environment.” He was correct in stating that many detailed theories are needed for the many components of rehabilitation, but I hope my theory overcomes his gloomy prognosis.

The ideas in this theory were put forward decades ago. I have pieced them together. The critical insight arose when I was asked to lecture to physicians on “recovery and rehabilitation after stroke”. I did not want to give a standard and boring lecture. While walking the dog, I wondered how to define a ‘no rehabilitation’ (i.e. recovery) control group in contrast to a rehabilitation group in a hypothetical trial. I realised why it was impossible – we could not prevent the patient from adapting as best they could, with the assistance of anyone around.

I have explained further aspects of this theory:

Adapting to change.

When I realised that a ‘no rehabilitation’ group would be impossible to establish because people would always offer help and advice, I soon realised that there was also no ‘natural recovery’ arising without some input. We could not stop someone trying to walk or move their arm. Further, we know from animal experiments that, after a stroke, the recovery of rats is better in an enhanced environment. I soon realised that observing natural recovery was equally impossible because people inevitably adapt to manage as they are and try to get better.

I, therefore, realised that any study of recovery or rehabilitation must be analysed in the context of ongoing, natural adaptation and change by the person. Although I was considering this for patients after a stroke, it applies in all circumstances. I recalled seeing someone with adult muscular dystrophy progressing slowly who could still walk, although she had very little strength; she balanced on her legs with the help of a frame. Another person aged 19 years with cerebral palsy once came to my clinic, walking independently in a very contorted way – but he was satisfied and was a busy student.

In other words, anyone who falls ill or has a progressive illness will adapt to their illness as best they can.

This is well-known but curiously overlooked. For example:

  • At the level of body structure and function, demand-based adaptation is a pervasive phenomenon.” [John Whyte, 2007]
  • , “Illness behaviour arises in response to circumstances that challenge the ongoing homeostasis. People are extraordinarily adaptive, but some changes in the situation, whether arising within the organism or from external factors, induce self-consciousness and appraisal and require assessments about the nature of the problem, its causes, and the strategies to be initiated.” [David Mechanic, 1986]
  • The fact of illness requires that the sick adapt to illness. This adaptation is moulded by society through cultural, social, institutional and biomedical mechanisms of interaction.” [Joseph Young, 2004]]
  • “… the ability to adapt to new, more limited capacities and the creativity that emerges …”. [Havi Carel, 2008]

What is adaptation trying to achieve? Most adaptation is relatively short-term and aims to maintain a relatively stable state; stability usually refers to continuing with some goal-directed activity despite some event disrupting the activity. If your car breaks down, you will get to work by taking a bus or getting a lift. If it is raining, you will take an umbrella. If you break a leg, you might work from home.

Suppose the event is more substantial, such as losing your job. In that case, you may actually seek help from an employment agency or an organisation that offers to retrain, and you may also seek advice from someone about finances. The adaptive process may take months or years. Nonetheless, everyone has some general goals they wish to achieve, and they will, where possible, continue to strive.

What are the targets?

In 1943, an American psychologist published his theory of motivation. He recognised that although people’s goals varied, they had much in common. He hypothesised that five areas of human need would represent most human needs. Abraham Maslow’s hierarchy of needs is still used now, and it is supported by much evidence. For example, Louis Tay and Ed Diener found that a higher level of fulfilling these needs was associated with greater subjective well-being.

The five areas of human needs that people are motivated to satisfy are:

  1. Basic physiological needs such as hunger and thirst,
  2. Self-protection, safety, and security needs such as somewhere to live,
  3. Affiliation, belonging needs, in particular, close emotional relationships and being part of a social group,
  4. Esteem needs, self-esteem and being respected by others as having a status,
  5. Self-actualisation, which refers to a group of needs that may be subdivided into:
    1. Acquiring knowledge and skills (cognitive knowledge),
    2. Adhering fully to a chosen philosophical, religious, or other moral system (moral needs)
    3. Contributing to society (social needs)

My post on Maslow’s needs gives more details about these needs and how they influence rehabilitation.

Achieving equilibrium (homeostasis).

The third building block of my hypothesis is homeostasis, which maintains bodily equilibrium within acceptable limits. The concept was used by Walter Cannon in 1926 to describe physiological mechanisms for animals to maintain a stable biochemical state within safe limits. The concept of homeostasis has been applied to many systems, including:

  • Social homeostasis in rats and people, including studies of neural circuitry.
  • Psychological (emotional) homeostasis was first mentioned in 1942 and listed by Radhakamal Mukerjee as one of ten areas of human homeostasis in 1966; the normative value for each was also given.

The mechanism to achieve and maintain a balance in these areas influences a person’s behaviour. David Marks has published a General Theory of Behaviour. In a later paper, he suggests that “human thriving is dependent upon an intrinsic homeostasis system with purpose, desire and intentionality striving to maintain equilibrium.”

This requires a central homeostatic network to monitor progress towards these goals and alter behaviour if needed to achieve them. Some evidence for such a network has been presented above concerning social interaction. Additional evidence has been published by Brian Edlow et al., Sheri Mizumori and Yong Jo, and David Marks.

A general therory of rehabilitation: summary so far.

I hope I have established that:

  • Humans respond to change in their circumstances by adapting their behaviour
    • This adaptation may be temporary or long-term
    • Most long-term adaptation involves other people offering advice and support
  • Human behaviour is motivated to achieve five basic needs;
    • the detailed goals and methods within each area of need will be personal
  • The person will strive to achieve and maintain an acceptable balance
    • between the areas of need
    • towards a personally-determined goal (set point) within each need
  • There are plausible central neural networks that
    • Monitor achievement, for example, of social needs
    • Alter behaviour if needed to increase achievement

The process of adaptive homeostasis is illustrated in the figure below.

Homeostatic adaptation in health

Illness, adaptation, and healthcare.

Falling ill is a significant happening in anyone’s life, and they will immediately start adapting their behaviours to accommodate the changes and to reduce them. The event causing change is within the body. It impacts the person’s ability to interact with their physical or social environment, which may influence their ability to meet their needs. The event additionally may limit the person’s ability to adapt; this distinguishes illness from most other changes precipitating adaptation.

Initially, most people seek a diagnosis and explanation of what is happening and what can be done. The healthcare system will look for a disease and, if identified, will offer treatments to cure or control it.

During this early phase, usually over days or a few weeks, society provides support: healthcare gives care to people in the hospital, and family and friends help at home. Financial and other support may be given to people with more severe illness. Although it provides direct care to people who are disabled, the health service does not routinely offer any input into adapting to and reducing the disability. Indeed, in hospitals, the physical and cultural environment usually inhibits any effective adaptive response.

The professionals involved in the response to illness will act within a biomedical healthcare theory. Undoubtedly, they may advise on how to react to acquired disabilities. Still, it is rarely expert advice; some advice or help may be inappropriate or harmful.

The only service with expertise in understanding the broader consequence of illness beyond the immediate disease is the rehabilitation service.

The only service with expertise in understanding the broader consequence of illness beyond the immediate disease is the rehabilitation service.

Adaptation; the role of rehabilitation.

I will first emphasise that adaptation to illness is not simply accepting the situation and coping with it, but no more. Adaptation is an active process. The person will strive to:

  1. Return as far as possible to a previous state,
  2. Continue social roles and participation, albeit in different ways
  3. Continue activities they want to undertake, albeit in different ways
  4. Alter social roles and activities while still aiming to satisfy their high-level goals (Maslow’s needs)
  5. Adjust their higher-order long-term goals.

The paragraph above assumes the person has achieved things before becoming ill. For people with congenital problems or illnesses starting in childhood or early adulthood, the goal will not relate to a previous state. Instead, it will usually relate to a desired or expected state, reflecting the achievements of healthy contemporaries and influenced by cultural factors.

The process of adaptation to a new health condition or worsening one already present is shown in the figure below.


Adapting to an illness

The central role of rehabilitation is to facilitate and support the person’s adaptation process and often that of their family and close friends.

Rehabilitation expertise offers the following to any patient with limitations on their activities or social participation associated with an illness, whether a disease is identified or not:

  1. A person-centred formulation, an accurate explanation of the clinical situation considering all aspects
  2. A prognosis, explaining what may happen and the various options available to optimise the long-term outcome
  3. A plan based on the person’s priorities and considering what is practical or available. This plan may include advice or information on
    1. Self-management
    2. Equipment and adaptations that may help
  • Other organisations that may help with care and support, such as Social Services.

These parts of the rehabilitation process should be available to anyone with newly acquired difficulties; one cannot know who might benefit from this first step. As will be discussed, these are catalytic actions.

Following on from this, the rehabilitation service may offer one or more of these active rehabilitation processes:

  1. Help in learning (practising) or relearning activities
  2. Training in self-management, including setting goals
  3. Appropriate equipment and adaptations, including how to use them
  4. Help in organising care from Social Services
  5. Palliative treatments to alleviate any pain, distress or other symptoms
  6. Support and education for families and carers

The place of rehabilitation within the adaptive processes is shown in the figure below. You should note that it may act on the person’s activities to optimise capabilities, or it may act on the physical or social context to assist the person in achieving a higher level of capability.

Role of rehabilitation in adaptation

General theory of rehabilitation; types of rehabilitation action

Rehabilitation activities can be divided into those with a dose-response relationship and those where the time and effort expended will not be related to the extent of change. The latter group can be further subdivided into actions concerned with the acquisition and use of data and those that facilitate adaptation without any relationship between the time and effort given and the change in outcome seen. Activities in the latter group have a catalytic effect.

The resultant three groups are detailed next.

Diagnostic actions.

As in all healthcare, the vital first step is understanding the situation well enough to make decisions and act safely.

In biomedical healthcare, this is known as making the diagnosis, which may, initially, be presented as a differential diagnosis requiring further investigations or treatment trials. It ends with a single diagnosis, which may be a pathology which can be confirmed externally, for example, by biopsy, culturing an infective agent, or demonstrating an imaging abnormality. Often, the diagnosis is less secure, such as fibromyalgia or chronic fatigue syndrome.

In rehabilitation, this is known as undertaking an assessment, and it ends with a formulation, which is not a single word or phrase but an analysis outlining the causes and interactions that contribute to and explain the situation. There is no differential diagnosis; instead, there is an acknowledged uncertainty about the exact contribution of each identified cause and that there may well be other unidentified contributing factors.

At the end of the process, the team can give:

  • A diagnostic formulation of causes
  • An estimate of prognosis given for each of a range of possible interventions
  • A plan that takes into account the person’s priorities

Catalytic actions.

Many actions of a rehabilitation team are not ‘dose-dependent; they affect change by altering something to allow better adaptation. These are catalytic effects.

Providing accurate, straightforward information and advice is a powerful and catalytic intervention. The diagnostic process culminates in an explanation and plan which can be given to the person, their family and friends, and any other services involved. It will include information on what is possible and advice on achieving it with a plan to assist. This will often lead to a much better outcome. It may avoid fruitless, wasted efforts or prevent the person from giving up because they cannot see any way forward.

Advising on and providing equipment or organising other environmental changes and adaptations is a second group of catalytic actions. These may take time and effort to manage because the healthcare and other systems are so complex, but there is no dose-response effect. The health service could save resources by streamlining and simplifying the process and reducing delays in funding, for example.

A third catalytic group of actions is organising care for patients. The healthcare and social care systems are Byzantine in their complexity, with long delays and much bureaucracy. It would be irresponsible to say that “care is not our responsibility”, so rehabilitation services spend much time and effort organising care. This is also not a treatment with dose-response characteristics. Sometimes, carers need training, which does have a dose-response aspect.

Assistive actions.

The traditional view of rehabilitation is therapy, a therapist teaching a patient and helping them practice an activity; it is a direct analogy to treatment in the biomedical healthcare model. This is undoubtedly an essential part of rehabilitation with a weak dose-response relationship, but other therapeutic activities exist. The rehabilitation team may:

  • Teach carers how to help the person adjust (part of rehabilitation) and how to provide care safely and effectively, especially when the person has high care needs
  • Help the person with their emotional state,
  • Help the person adjust their goals, reducing or increasing their aspirations
  • Correct inappropriate beliefs or expectations if they are hindering adaptation or causing distress or other risk or harm
  • Support and advocate for the person in negotiations about care, employment or other matters.



The rehabilitation actions involved are shown in the fourth and last figure here. Activities in all three groups may benefit the person considerably.

Rehabilitation actions


The general theory of rehabilitation presented here draws on ideas and evidence published over the last 90 years. The basic premise is that people adapt to illness and that rehabilitation is an expert healthcare service that facilitates adaptation to optimise the person’s long-term outcome. The starting point is that adaptation is a natural response to any change in a person’s situation, and illness is one change distinguished from others because it involves the person and thus may directly limit the person’s ability to adapt. The main additional building block is that the person has a central homeostatic network to maintain an equilibrium in a person’s five main areas of need. It compares progress towards and achievement of needs with the five areas and influences behaviour to achieve the needs. Rehabilitation provides a better understanding of the causes and interactions leading to the situation and provides information on prognosis and ways to optimise the person’s adaptive changes. Rehabilitation activities include catalytic activities, where the degree of alteration in outcome is unrelated to the rehabilitation time and effort involved, and others that assist directly with a weak dose-response relationship.

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