What is the diathesis stress hypothesis How does it explain the development of schizophrenia?

What Is Diathesis | Diathesis Stress Model | Diathesis and Stress

Although stress is an inevitable part of a person’s life, it has different effects on different people. Some people develop psychological disorders after being exposed to major environmental stressors, while others do not.

Scientists have been trying to find out and explain what causes this difference in outcomes. The diathesis-stress model is one explanation based on scientific understanding.

What is the diathesis-stress model

The diathesis-stress model describes how the interaction of predisposition (diathesis) and stressful situations (stress) can trigger physical or mental health disorders. It is also known as the stress-vulnerability model or stress-diathesis model.

Diathesis is a person’s predisposition or vulnerability to a medical condition, which can be a psychological or physical disorder. This terminology was first used in psychiatry in the study of schizophrenia, and later depression.

This predisposition can be inherited genetically​1​, created by environmental stressors early in life, or caused by the genetics x environment interaction (GxE) ​2​.

According to the diathesis-stress theory, stress is more likely to lead to physical or mental illnesses in someone predisposed to it as opposed to someone without the disposition​3​.

The Dual Risk Model

The diathesis-stress model is also known as the dual risk model​4​ because stress is a risk factor that has two roles here.

Certain environmental risk factors may increase a person’s predisposition in early life. This early life experience can lower an individual’s threshold for developing mental disorders, and allow subsequent stressors to trigger the disorders more easily.

Examples of risk factors include punitive parenting​5​, childhood maltreatment, physical or sexual abuse​6​, and young girls​7​.

Stress, therefore, plays a dual role​8​:

• Early stress exerts a formative influence on children increasing their underlying vulnerability to psychological disorders.
• Later stress exerts a precipitating or triggering influence by activating the actual onset of the disorders.

Diathesis-Stress Interaction

According to the Diathesis-Stress Model, mental health problems can be triggered by the presence of both predispositions and stress.

This is a plausible explanation for why some people develop mental disorders when facing stressful life events while others don’t.

At first glance, this model suggests that diathesis and stress are two independent qualities that could exist on their own without the other. In this early version of the Diathesis-Stress Model, the interaction between vulnerability and stress was clear cut: Stress activated the diathesis, which in turn brought about the onset of the disorder​9​.

But in recent years, researchers have discovered several ways in which diathesis and stress can actually interact and influence each other.

Diathesis Can Cause Stress

One possible interaction between diathesis and stress is that the underlying predisposition may cause or affect the experience of stress. That is, having certain vulnerabilities may increase one’s likelihood of incurring a high level of stress.

For instance, a genetic vulnerability may cause a person to cope with life in a way that creates a stressor that normal people without the trait will not experience.

This bidirectional influence can be seen in some individuals predisposed to depressive symptoms. These individuals may exhibit irritability, fatigue, and social withdrawal. These symptoms can cause problems in their interpersonal relationships and employment. If those problems end up causing the loss of a close relationship or job, then those experiences become the stressors that catalyze the onset of major depressive disorder​8​.

In this scenario, stress is not just a random event, but the consequence of having a vulnerability.

Another type of interaction is that vulnerabilities can alter a person’s perception of stress.

For example, a vulnerable person may perceive an ordinary experience as a highly stressful event. The vulnerabilities essentially cause high levels of psychological distress.

Stress can Cause Diathesis

While diathesis can lead to stress, stress can also lead to diathesis. As previously discussed, environmental stress can cause a person to develop vulnerability.

In the depression scar hypothesis, the first episode of a person’s major depression may cause them to form negative thinking patterns. These new thinking patterns then become the vulnerability and lead to later episodes of depression when further stressful events are encountered​10​.

In recent years, scientists have found another pathway for stressful events to create a biological vulnerability. They found that some environmental factors can modify gene expression through epigenetic processes. Such modifications are independent of the genetic makeup of a person.

That means even if a person is not born with a genetic predisposition, certain environmental or social factors can still alter the person’s DNA to create a biological predisposition.

Diathesis stress model and parenting

The Diathesis-Stress Model is a complicated psychological theory that keeps evolving as scientists continue to gather new information. Meanwhile, this model helps to explain why some children seem more resilient than others.

The diathesis stress theory consolidates existing research on parenting proving that parenting matters. Lack of parental emotional support, authoritarian parenting, and domestic violence are among the risk factors that can lead to vulnerabilities in children​11​. Children who grew up under these conditions are at a high risk of depression and other serious mental illness.

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