Stress: Vulnerability to Psychosis

The vulnerability–stress model describes psychosis as emerging through interactions between susceptibility and demands. Susceptibility may involve genetic, developmental or other factors, while stress includes social, psychological and physical pressures. Protective influences, such as reliable support and effective treatment, also shape the balance.

Stress is the response to demands or threats that challenge a person’s resources. It involves psychological experience, bodily changes and social circumstances. In schizophrenia, stress may influence symptoms and functioning, but it is not a complete explanation of the illness. The same situation can affect different people in different ways.

The model is a useful framework rather than a precise equation. It cannot identify a personal threshold or prove why one episode occurred. People can develop symptoms without an obvious stressor, and many stressful experiences do not lead to psychosis. The model should therefore avoid blame or excessive restriction of ordinary life. Its clinical value is to identify modifiable pressures and helpful resources. A person may benefit from changes in workload, sleep support or treatment even when their underlying susceptibility cannot be measured or the exact cause of an episode remains uncertain.

Protective factors can be social as well as individual. Predictable services, supportive relationships and secure living conditions may reduce demands or make them easier to manage. The model therefore supports changes to the environment, not just training the person to tolerate more pressure. It also recognises that susceptibility is probabilistic and does not dictate one unavoidable response to every stressful event.

Further reading: National Institute of Mental Health; Research record 25688430.