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The Stress-Vulnerability Model
of Co-occurring Disorders

  • What causes psychiatric disorders?
  • Why do some people develop a psychiatric disorder but others don't?
  • What affects the course of the disorder?

These are common questions raised by people with co-occurring disorders and their family members. The stress-vulnerability model provides answers to these questions. This model can help in understanding the causes of psychiatric disorders, how psychiatric disorders and addiction can influence each other, and how co-occurring disorders can be managed and treated together.

Handout available

This information is also available as a PDF, which is included in the Hazelden Co-occurring Disorders Program.

Download the Stress-Vulnerability Model handout

As the name suggests, two main factors are involved. "Vulnerability" refers to our basic susceptibility to mental health disorders. This is determined by our genetic makeup and our early life experiences. It is affected by our use of medications and our likelihood of using alcohol or drugs. "Stress" refers to the challenges faced in our lives. It is affected by our coping skills, social support, and involvement in meaningful activities.

Biological Vulnerability

If we are vulnerable to something, it means we're more likely to be affected by it. For example, some people might be biologically vulnerable to certain physical illnesses-such as heart disease or asthma. Maybe the disease runs in the family, or maybe something in our early life "set us up" for it.

Some people are biologically vulnerable to certain psychiatric disorders: bipolar disorder, major depression, schizophrenia, or anxiety disorders (panic, post-traumatic stress), for example. This vulnerability is determined early in life by a combination of factors, including genetics, prenatal nutrition and stress, birth complications, and early experiences in childhood (such as abuse or the loss of a parent). This is why some families are more likely to have members with a particular psychiatric disorder. Although vulnerability to psychiatric disorders is primarily biological in nature, people can take steps to reduce their vulnerability, including taking medication and not using alcohol or drugs. It's also worth noting that the greater a person's vulnerability to a particular disorder, the earlier it is likely to develop, and the more severe it may become.

Similarly, some people also have a biological vulnerability to developing an addiction: they are more likely to develop alcohol or drug abuse or dependence. This is why addiction, similar to psychiatric disorders, sometimes "runs in families."

What Are the Elements of the Stress-Vulnerability Model?

These two main areas -- biological vulnerability and stress -- are influenced by several other factors that people have some control over. These factors include

  • alcohol and drug use 
  • medication use 
  • coping skills 
  • social support 
  • meaningful activities

This means that by addressing these factors, people can reduce symptoms and relapses and improve the course of their co-occurring disorders.

Alcohol and Drug Use

Using alcohol or drugs can increase a person's pre-existing biological vulnerability to a psychiatric disorder. Thus, substance use can trigger a psychiatric disorder and lead to more severe symptoms and other impairments. Because most people with co-occurring mental and substance use disorders have a biological vulnerability to psychiatric disorders, they tend to be highly sensitive to even small amounts of alcohol and drugs.


Stress in the environment can worsen biological vulnerability, worsen symptoms, and cause relapses. Stress is anything that challenges a person, requiring some kind of adaptation. Serious stressful events include losing a loved one, getting fired from a job, being a victim of crime, or having conflicts with close people.

Stress is often associated with negative events, but positive events and experiences may be stressful as well. For example, performing well in school, getting a new job, starting a new relationship, having a baby, or being a parent all involve some degree of stress.

It is also possible for stress to be caused by not having enough to do. When people with co-occurring disorders have nothing purposeful or interesting to do, they tend to have worse symptoms and are more prone to using substances. So a lack of meaningful involvement in life-in areas such as work or parenting, for example-can be another source of stress.

Coping Skills

Developing coping strategies can help with handling stress and reducing its negative effects on vulnerability. Examples of coping skills include

  • relaxation skills for dealing with stress and tension 
  • social skills for connecting with people, dealing with conflict, and getting support 
  • coping skills for managing persistent symptoms such as depression, anxiety, and sleeping problems

Stress is a normal part of life. Effective coping enables people to be engaged in interesting, rewarding activities that may involve stress, such as working or being a parent. Coping efforts can make it possible for someone with co-occurring disorders to live a normal life without suffering the negative effects of stress.

Involvement in Meaningful Activities

Having something meaningful to do with one's time gives one a sense of purpose, and reduces the stress of having nothing to do. Meaningful activities can include:

  • work 
  •  school 
  •  parenting or other caregiving responsibilities 
  •  homemaking

Social Support

Another way to reduce the negative effects of stress on vulnerability is through social support, which comes from having close and meaningful relationships with other people. Supportive people can help in a variety of ways, such as

  • helping people solve challenging Problems 
  • supporting people in using coping strategies to deal with symptoms and substance-use urges 
  • being open and willing to discussing and resolving personal disagreements, misunderstandings, and areas of conflict that could otherwise lead to stress 
  • letting people know that they are important and cared about 
  • supporting the person in pursuing personally meaningful goals

People who have good social support are less vulnerable to the effects of stress on their psychiatric disorder. Therefore, having strong social support enables people with co-occurring disorders to handle stress more effectively, and live a normal life.

Treatment Implications of the Stress-Vulnerability Model

Based on an understanding of the stress-vulnerability model, there are many ways to help people manage their psychiatric illness and co-occurring substance use disorder. In the broadest terms, the severity and course of a co-occurring mental health disorder can be improved by reducing biological vulnerability and increasing resiliency against stress.

Reducing Biological Vulnerability

Biological vulnerability can be reduced in two primary ways: taking medication and avoiding alcohol or drug use. Medication can be a powerful way of reducing biological vulnerability by helping to correct the imbalances in neurotransmitters (chemicals in the brain responsible for feelings, thinking, and behavior) believed to cause psychiatric disorders. By taking medication, the symptoms of a psychiatric disorder can be lowered and the chances of having a relapse can also be reduced.

Avoiding alcohol and drug use can reduce biological vulnerability in two ways. First, because substances affect the brain, using alcohol or drugs can directly worsen those vulnerable parts of the brain associated with psychiatric disorders. Second, using substances can interfere with the corrective effects of medication on vulnerability. This means that somebody who is using alcohol or drugs will not get the full benefit of any prescribed medications for his or her disorder, leading to worse symptoms and a greater chance of relapses.

Increasing Resiliency against Stress

It is impossible for anyone to live a life that is free of stress. However, there are many ways people can learn how to deal with stress more effectively, and to protect themselves from the effects of stress on worsening symptoms and causing relapses, including

  • developing effective coping skills for managing stress and persistent symptoms 
  • getting involved in meaningful activities that structure one's time and reduce the stress of having nothing to do 
  • building socially supportive relationships that help one manage the mental health disorder and maintain sobriety


Focus on Integrated Treatment:
This webinar provides an overview of FIT and explains its role in providing the tools and training needed to become certified to treat clients with co-occurring disorders.
Professional Development

Hazelden offers many courses to help you expand your knowledge about alcohol and drug addiction and mental health disorders, including:

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