The diathesis stress model views psychological disease as the result of the interaction between a person's vulnerability for a disorder and stress. A susceptible individual may never manifest a mental illness until he encounters a type or degree of stress that is enough to trigger it. It seeks to explain how different people may respond differently to the same source of stress.
The Theory
The diatheses stress model is one of several theories used over decades to try to understand and explain the complexities of psychological illnesses such as schizophrenia and depression. This model believes that people develop a psychological disorder in response to stress because they have an underlying predisposition to the disease.
This underlying vulnerability (diathesis) comes from genetics, or biologic predisposing factors. Environmental stresses interact with the diathesis to trigger a psychological disease in a person.
In this theory, neither predisposition nor stress alone can trigger mental illness, rather, stress triggers the diathesis and both interact in some way to manifest the disease state. The more vulnerable a person is and the lower his threshold, the less stress it takes to trigger a disorder.
Individual Variation
Vulnerability explains why one person may develop depression or a major psychiatric disorder while another does not, even though they encounter the same stress. Because the level of diathesis and resilience varies from one person to the other, people vary in how they respond.
The Predisposition
The diathesis or vulnerability to a psychological disorder lies quiet until a person encounters stresses in his environment. Diathesis factors can include:
- Genetics, such as having a family history of a psychological disorder that might be related defective genes
- Biologic, such as oxygen deprivation at birth or poor nutrition during early childhood
- Childhood experiences, such as isolation, loneliness or shyness that creates a distorted view of the world
Part of the theory is that everyone has a certain level of vulnerability and a certain threshold for a stress to trigger disease. The more vulnerable you are and the lower your threshold, the more likely that a mental disorder will manifest.
Stress Factors
Stress factors that can interact with a person's predisposition for psychological disease can range from mild to major stressors and include:
- Minor daily stress in home or external environment
- Life events such as a family death, a divorce, starting school
- Short-term factors such as a school or a work assignment
- Long-term stress such as chronic pain or an ongoing illness
Modifying Protective Factors
Protective environmental factors can modify the interaction between diathesis and stress. Your protective factors, or resilience, can prevent a mental illness. An individual's modifying factors might include:
- A protective social environment
- Family nurturing
- Healthy self esteem
- A network of friends and strong social support
- Normal psychological development and interaction during childhood
These protective factors can dampen negative interactions between stressors and vulnerability in an individual.
Application of the Model
It is thought that the model can be viewed in different ways depending on the ways various diathesis factors may interact with stress. The concept can also be applied differently depending on the disorder. A theory also is that different psychological disorders are triggered by different underlying diathesis and different stress factors.
For example, schizophrenia may be triggered in someone whose diathesis, for example, is worsened by being raised in an isolated, unloving environment. In this case, stress may act at the level of the hypothalamus and pituitary glands through the stress hormone cortisol to interact with the underlying vulnerability to trigger or worsen the individual's schizophrenia.
Several risk factors that make up a person's predisposition, together with various environmental conditions during development, may later interact with stresses and modifying factors to trigger one psychological disorder or another in a susceptible person.
History
The term "diathesis-model" was first used in the 1960s as a theory to explain schizophrenia but has since come to be applied to other psychological conditions such as:
- Depression
- Anxiety disorders
- Manic-depressive disorder
- Post-traumatic stress syndrome (PTSD)
- Alcoholism
- Sexual dysfunction
- Personality disorders
- Eating disorders
The model is now being applied to looking for modifications in genes that would explain genetic susceptibility to disease.
A Unifying Model
Disease models help mental health professionals to better understand complicated disorders. The diathesis stress model is used to explain many psychological illnesses using a single theory of how illness develops. It helps to unravel how underlying vulnerability interacts with different stress factors to initiate psychological disorders.
