Vulnerability and Stress: Why Are Some People More Vulnerable Than Others?

In this article, we will explore why some individuals are more vulnerable to stress, while others seem to cope and move on, regardless of adversity.

Consider two examples:

• Bill and Jack experience the same traumatic car accident. Bill processes the event, adapts, and moves forward. Jack, however, develops PTSD (Post-Traumatic Stress Disorder).
• Susan and Mary are sisters, both genetically predisposed to schizophrenia. However, only Mary develops the disorder after a mental breakdown following her breakup as a teenager.

To explain these differing outcomes, we need to understand a few key concepts, beginning with vulnerability.

Definition of Vulnerability

Vulnerability refers to an individual’s susceptibility to harm or difficulty when faced with adverse situations. This can involve both physical and psychological health, where some people may be more prone to illness, emotional distress, or maladaptive responses. Vulnerability stems from genetic, biological, psychological, and environmental factors. In the case of Susan and Mary, both have a genetic vulnerability. What does this mean in practice?

Genetic Vulnerability

Genetic vulnerability refers to the hereditary factors that increase the likelihood of developing certain conditions. For example, individuals with a family history of schizophrenia, depression, or cardiovascular disease may be more vulnerable to these conditions. However, whether or not the disorder manifests often depends on the interaction between genetic vulnerability and environmental stressors. In the example of Susan and Mary, while both are genetically vulnerable, the intensity of their stressors differs. Mary experienced a significant stressor—the breakup—which may have triggered her schizophrenia. Bill and Jack’s case may also be explained by their varying levels of vulnerability. Bill’s resilience allowed him to cope with the accident, while Jack’s higher vulnerability made him more likely to develop PTSD.

Definition of Stress

Stress is a physiological and psychological response to perceived threats, challenges, or demands. It can be triggered by external stressors and affects both physical and mental well-being. Stress can cause the body’s “fight-or-flight” system to activate, releasing hormones like adrenaline and cortisol. In short-term situations, this response is adaptive, preparing the body for immediate danger (like facing a predator). However, chronic stress, where stressors are persistent, can lead to harmful effects on the body and mind.

Types of Stressors

Stressors are external events or conditions that challenge an individual's ability to cope. These can include:

• Environmental stressors: Accidents, financial problems, job pressures.
• Interpersonal stressors: Relationship conflicts, social isolation.
• Internal stressors: Personality traits like neuroticism, self-criticism, or pessimism.

In Bill and Jack’s case, both experienced the same external stressor—a traffic accident. Bill was more resilient, while Jack was more vulnerable. For Mary, an interpersonal stressor (her breakup) likely triggered the onset of schizophrenia. To understand why some people develop mental disorders in response to stress while others do not, we need to look at the vulnerability-stress model.

Vulnerability-Stress Model (Zubin)

The vulnerability-stress model, developed by Zubin and Spring in the 1970s, was originally proposed to explain the onset of schizophrenia. This model posits that individuals have varying levels of inherent vulnerability to psychological disorders based on genetic, biological, or psychological factors. Vulnerability alone, however, doesn’t cause a disorder; it must interact with external stressors to trigger mental illness. Over time, this model has been extended to a wide range of psychological and physical conditions, including PTSD, depression, and cardiovascular diseases.

Levels of Vulnerability and Resilience

Individuals with high vulnerability, like Jack and Mary, require only a small amount of stress to experience symptoms, while those with lower vulnerability, like Bill, can endure higher levels of stress without harmful effects. In Susan’s case, despite her genetic predisposition to schizophrenia, the absence of significant stressors has allowed her to remain healthy. This brings us to the concept of resilience.

Resilience

Resilience is the capacity to maintain or regain psychological well-being despite adversity, stress, or trauma. Resilient individuals can experience negative events but still retain their ability to function, solve problems, and regulate emotions. Resilience is influenced by factors such as:

• Social support: A strong network of supportive relationships.
• Personality traits: Optimism, positive self-image, and emotional regulation.
• Learned coping strategies: Adaptive responses to stress developed over time.

People like Bill, who are resilient, can manage stress with ease, while others may be more sensitive and have a lower tolerance to stressors, like Jack and Mary.

The Role of Neuroticism

One factor that can explain why people respond differently to the same stressors is neuroticism, one of the Big Five personality traits. Neuroticism is characterized by a tendency toward anxiety, emotional instability, and sensitivity to stress. Individuals with high levels of neuroticism often have lower stress tolerance and are more prone to negative emotions, making them more vulnerable to mental health issues. Bill and Jack both experienced the same accident, but Jack’s higher neuroticism may have contributed to his more intense emotional reaction, leading to PTSD.

Conclusion: Why Are Some People More Vulnerable?

The vulnerability-stress model provides a framework for understanding why some people develop mental health issues in response to stress while others do not. While genetic and biological factors play a role, external stressors and individual traits, such as resilience and neuroticism, also shape how individuals react to stress. People like Bill, who are more resilient, can manage stress more effectively, while those with higher vulnerability, like Jack, Mary, and Susan, may be more prone to mental illness when exposed to stressors.

References

• Zubin, J., & Spring, B. (1977). Vulnerability—a new view of schizophrenia. Journal of Abnormal Psychology, 86(2), 103–126.
• Ingram, R. E., & Luxton, D. D. (2005). Vulnerability-stress models. In B. L. Hankin & J. R. Z. Abela (Eds.), Development of psychopathology: A vulnerability-stress perspective (pp. 32–46). Sage Publications.
• Lazarus, R. S., & Folkman, S. (1984). Stress, appraisal, and coping. Springer Publishing.
• Connor, K. M., & Davidson, J. R. T. (2003). Development of a new resilience scale: The Connor-Davidson Resilience Scale (CD-RISC). Depression and Anxiety, 18(2), 76–82.