Background: There is no general theory of rehabilitation, only definitions and descriptions, with the biopsychosocial model of illness as a structure.
Objective: To develop a general theory of rehabilitation that explains how healthcare rehabilitation changes outcomes and to evaluate its validity.
Need: A general rehabilitation theory would help research, improve services, increase understanding, modify resource allocation and explain some anomalies, such as how rehabilitation helps when no natural recovery occurs.
Building blocks: People adapt to change throughout their lives. Illness is a change, and people adapt to their illness. Adaptation's purpose is to maintain an equilibrium in a person's life. The balanced components are related to Maslow's five needs: basic, safety, affiliation, status and self-fulfilment. The general theory of behaviour suggests that a person's behaviours change to maintain balance, regulated by a central homeostatic mechanism.
The theory: Rehabilitation aids adaptation to changes associated with illness through accurate diagnosis and formulation, catalysing adaptation, optimising the environment and assisting the person in making necessary changes by safely practising activities and teaching self-management.
Implications: The theory makes the person the central active agent, emphasises the importance of the environment in facilitating adaptation, explains why all conditions may benefit, including progressive and static conditions, suggests that health can be equated to someone maintaining their equilibrium and explains why a small dose may be very effective.
Conclusion: The general theory of rehabilitation emphasises the catalytic effects of rehabilitation in facilitating and guiding adaptation and suggests areas for research and improvement.
Keywords: Rehabilitation; adaptation; biopsychosocial model; catalyse; theory.