One of the sociocultural explanations of Major Depressive Disorder is the vulnerability model of mental illness.  This model argues that depression is the result of having more risk factors in one’s environment than protective factors. The sociocultural approach is able to explain class and gender differences in the prevalence of depression – as well as explaining how prevalence levels can change over time.  However, the sociocultural approach has difficulties establishing a cause and effect relationship between sociocultural factors and the onset of depression.

One study that looked at how environmental risk factors play a role in depression was carried out by Brown and Harris. The sample was made up of 500 women in London. The women filled out questionnaires about stressful life events, biographical information, and their mental health.  They found that 8% of the women had been diagnosed as depressed. 90% of those women had experienced adverse life experiences in the past year. This was compared to only 30% of women who were not depressed.  The researchers argued that risk factors – such as the loss of a spouse, more than three children at home, and unemployment – were all risk factors for depression that make a person more vulnerable to the disorder.  Protective factors – such as being a member of a community or having family support – were seen as protection against depression.

This research was one of the first to argue that the reason that women have a higher prevalence of depression than men may be because they are exposed to more risk factors.  However, there are some limitations of the study.  First, it was done in an individualistic society where extended family support is not common. There is also an expectation in individualistic societies that people be self-sufficient. This means that there may be a cultural bias with the research.  In addition, there is little attention in the study to cognitive factors.  How we process information is a mediating factor in how we cope with stress.  This is not accounted for in the study.   Finally, there is the question of how stress was measured.  The test used focused on major life events that are seen as stressful, but it may be that smaller stressors may also have a significant effect on a person’s health.  

The most significant problem with the study - and the theory itself -  is that it does not actually explain how these risk factors lead to depression – it simply draws a correlation between certain factors and depression. The study was done before the human genome project so genetics are not considered.  Today we use a more interactionist approach to understanding disorders.  It is possible that the environmental stressors lead to a chronic HPA axis response which then results in gene expression and depression. Research today shows that environmental stressors – such as adverse childhood experiences – have an effect on one’s long-term mental and physical health.  This would support Brown and Harris’s findings, but not limited to a sociocultural approach.

Hays, Turner & Coates also argue that a lack of social support may lead to depression and have an effect on one’s health.  The researchers found that gay men diagnosed with HIV were more likely to develop depression if they are rejected by family members. Once again, this is a correlation, so it may not be specifically the lack of family support that leads to depression. It is not possible to control for other variables and draw a conclusion about cause and effect.

The greatest limitation of this approach is that we cannot isolate either social or biological factors.  Coan et al carried out a study to see if having their husbands hold their hand would lower their level of stress during a threatening experience.  The women were threatened with an electrical shock.  When they saw certain images, this was a warning that they were going to be shocked.  The women would either hold their husband's hand, the hand of an anonymous male experimenter or no hand while they were in an fMRI. The results were that the brain's "threat response" was lowest when holding their husband's hand and strongest when no hand was held. In addition, by there was a negative correlation between their marital satisfaction and the threat response. Although one could argue that the presence of social support is a social factor, it is also linked to physiological responses in the brain which may play a role in preventing depression. It could be that the neurotransmitters and hormones that are released as a result of human touch act as a protective factor against depression.

Vulnerability models are unable to explain why some people develop depression when exposed to environmental stressors, but they do potentially help us to potentially prevent the disorder by providing more protective factors for individuals who may be at risk for the disorder. The idea that risk and protective factors may change over time helps to explain changes in prevalence rates. This is something that the biological approach alone cannot easily explain. In spite of this, it is difficult to argue how social stressors cause depression. It is only with the interaction of biological factors that the stressors appear to lead to the disorder. Our modern understanding of the gene-environment interaction shows the value of studying these vulnerability factors.

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