Diathesis, Stress, and Protective Factors: Understanding the Diathesis-Stress Model

Lesson Transcript
Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

Expert Contributor
Lesley Chapel

Lesley has taught American and World History at the university level for the past seven years. She has a Master's degree in History.

The diathesis-stress model states that mental disorders develop from a genetic predisposition for that illness combined with stressful life conditions. Learn about diathesis and stress, then explore the protective factors that provide a buffer between people and mental illness. Updated: 09/27/2021

Diathesis-Stress Model

Kathleen hears voices that aren't there, and she believes that she's a famous actress, even though she's never acted a day in her life. Other people notice that she acts oddly: she talks back to the voices only she can hear, and she's shocked when people don't recognize her as a star.

Kathleen is suffering from schizophrenia, a mental disorder that involves having hallucinations and delusions, among other symptoms.

Gene isn't like Kathleen; he's not hearing things or delusional. But, he is depressed. He's sad a lot and has lost interest in the things that used to make him happy. Not only that, he sometimes has trouble getting out of bed in the morning and focusing at work.

What could cause schizophrenia, depression, and other psychological disorders? Psychologists don't all agree. Some believe that psychological problems are primarily biological in nature; that is, they are caused by some underlying physical or neurological condition. For example, Kathleen's brain works differently from most people's. When she hears voices, the part of her brain that deals with hearing is active, as though she was actually, physically hearing someone talk.

Others believe that abnormality is mostly caused by a person's environment. They say that problems in a person's life cause psychological problems. Take Gene, for example: he and his wife are in deep debt, and they might lose their house to foreclosure. That could be causing his depression.

But, most psychologists agree that psychological problems are caused by a combination of biology and environment. The diathesis-stress model of abnormality tries to explain how biology and environment work together on people's minds. According to this model, people are born with a certain biological or genetic predisposition to a mental illness.

But, not all of those people will actually develop the mental illness they are predisposed to. Some will go on to lead happy lives and not end up schizophrenic, like Kathleen, or depressed, like Gene.

Some, though, will experience situations in their lives that increase the likelihood that they will develop the mental illness. If their life situation is serious enough, the combination of environment and biology will lead them to developing the illness.

Let's look a little closer at the diathesis-stress model, including the three main concepts linked to it: diathesis, stress, and protective factors.

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  • 0:07 Diathesis-Stress Model
  • 2:41 Diathesis
  • 3:58 Stress
  • 5:56 Protective Factors
  • 6:46 Lesson Summary
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The first part of the diathesis-stress model is diathesis, or vulnerability to a mental illness. Think of this like the starting line of a race, and think of the finish line as a specific mental illness, like depression.

In this race, though, not everyone starts at the same place. Some people are miles and miles away from depression, while others are very close to it. Genetics and biology determine how close you are to the 'finish line' of depression.

Someone like Gene, for example, might have a diathesis that is very high for depression. That is, he was born with a vulnerability for depression. That doesn't mean that he will definitely get depression, only that his starting line is closer to depression than yours or mine.

Kathleen, on the other hand, might have a diathesis that is very low for depression. Her starting line is very far away from depression. But, she might have a high diathesis for schizophrenia. Maybe her aunt and grandfather both had schizophrenia, and she inherited a gene that puts her 'starting line' for schizophrenia very close to the disease.

Each person's diathesis for any particular mental illness is different from other people's and can be influenced by biology or genetics.


Let's go back to the depression race. Gene's starting line is very close to the finish line: he's got a high diathesis for depression. Meanwhile, Kathleen's starting line is very far from depression. But, what does this mean? Does it mean that Gene definitely will get depressed and Kathleen definitely won't?

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Additional Activities

Prompts About the Diathesis-Stress Model:

Writing Prompt 1:

In a paragraph, explain the diathesis-stress model and how it works to explain the origins of mental illness.

Tip: Consider the way biology and the environment work together.

Writing Prompt 2:

Write an essay in which you answer and analyze the following question: If a person has a high diathesis for mental illness, does that mean that such person will automatically suffer from mental illness? Why or why not?

Example: First define diathesis. You might state, for instance, that someone might be genetically predisposed to Obsessive Compulsive Disorder (OCD) because his or her father has it. Then define and explain the role of stress in contributing to the person having OCD, and then define and explain the role of protective factors that could prevent the onset or diminish the severity of OCD.

List Prompt 1:

Make a list of the types of stress that can contribute to the onset of mental illness for someone who already has a high diathesis.

Example: Divorce.

List Prompt 2:

Make a list of the types of protective factors that can mitigate mental illness in a person who already has a high diathesis.

Example: Career success.

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