Major Depressive Disorder is a complex illness influenced by biological, psychological, and sociological factors. While genetics play a role, conferring a 37% risk, environmental influences like stressful life events are also significant, accounting for 60% of risk. The biopsychosocial model views depression as arising from interactions between these factors. Early childhood experiences like abuse, neglect, or unstable attachments can increase vulnerability by affecting neurobiological and psychosocial development. Positive social relationships and support are important for preventing depression, while stress, loss, and mental/physical health issues can trigger depressive episodes along with genetic and neurobiological vulnerabilities. A holistic understanding of individual cases is needed due to heterogeneity.

1. Running head: HUMAN BEHAVIOR IN THE SOCIAL ENVIRONMENT III MIDTERM 1
Human Behavior in the Social Environment III Midterm
Amanda M. Klein
New York University

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In 2010, 13 out of 17 American adolescents between the ages of 13 and 17 met criteria
for a psychiatric disorder, Major Depressive Disorder (MDD), being one of the most common
(Kagan, 2015). Despite the high number of people who have been hit with this illness, the
question still remains of how exactly it gets there? The answer is not simple, nor is there one
answer, for every individual is different, and there is typically not solely one factor that lands a
person in a major depression. This is why it is best to look at depression from a biopsychosocial
perspective. Gabbard explains that psychodynamic approaches to understanding depression
today recognize that the disorder is strongly influenced by genetic and biological factors (2014).
Current etiology of depression shows 40% genetic influence and 60% environmental influence
(Nemeroff, 2003), and it causes impaired functioning across social, cognitive, and occupational
domains (Koehler, 2015). Depression is viewed from a biopsychosocial perspective, in order to
view and understand the patient as a unique individual, keeping in mind the idea that “one size
does not fit all.” This biopsychosocial perspective also provides insight as to how biological,
psychological, and sociological factors relate to, interact with, and affect one another in the
formation and growth of this mental illness.
Even with other influences, biological and genetic factors play a significant role in the
pathology of Major Depressive Disorder. Humans are wired to need social interaction and
support, and it is actually necessary for survival (Bowlby, 1969). Lacking positive social
relationships can contribute to development of depression, and since neuroticism appears to
alienate social support, it indirectly plays a role in this pathology (Kendler et al. 1995). Stressful
life events heavily influence the biological factors that can contribute. Findings have shown that
a functional polymorphism in the promoter region of the serotonin transporter gene (5-HTT) can
moderate how the stressful life events impact depression (Caspi et al. 2003). Similar studies have

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lead to speculation that those with two s alleles in the 5-HTTLPR are more likely to become
depressed in response to relatively common and low-threat events (Gotlib et al. 2008). Kendler
found that the impact of stressful life events were in some ways gender specific (2011),
discovering that men were more sensitive to depressogenic effects of divorce/separation and
work problems, whereas women were more sensitive to the depressogenic effects of problems
encountered with individuals in their primary network (Nemeroff, 1999). Rates of MDD in
women are also twice as high as they are in men (Fall, 2015).
Whether depression is an illness that is inherited or not has been a constant debate, and
while there is heritability, it is not overly responsible for development. The largest meta-analysis
of twin studies estimated a genetic effect of just 37% for MDD (Burmeister et al. 2008). As
Panksepp puts it in his TED Talk, “Genes set the boundaries of the possible, but it is the
environment that parses out the actual” (2014), for genetic variations typically do not cause the
illness, but are responsible for creating certain vulnerabilities that exist when the individuals are
in certain situations (2014). It is also suggested that heritability estimates may be distorted due to
high genetic and heterogeneity and epigenetic changes, which involves the expression of a gene
at one location impacting the expression of a gene at another location (2008). In addition, major
depression can infringe on one’s physical health, placing people at higher risk for serious
medical conditions, such as cardiac arrest, strokes, and cancer (2015), and is estimated as the
fourth leading cause of disability in the world (WHO, 2015).
The stress-diathesis model agrees that there are multiple factors that work together in
forming this pathology, attempting to explain behavior as a predispositional vulnerability
combined with stress from life experiences. It is described as a genetic substrate might diminish
monoamine levels in synapses or increase reactivity of the hypothalamic-pituitary-adrenal axis to

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stress (Gabbard, 2014). Monoamine is a transmitter in the brain that gets released when someone
is happy, and therefore, a depressed person needs a monoamine inhibitor. When one is stressed,
cortisol is released. Therefore, monoamine levels go down, which indicates stress, and stress
often leads to unhappiness, and depending on the degree and other present factors, depression
(Nemeroff, 1998). For example, when someone is neglected or abused, their stress response
typically activates, leading to elevated activity in corticotropin-releasing factor (CRF)-containing
neurons, which are known to be stress responsive and to be excessively active in those who are
depressed (Hammen et al. 2000). These cells can then become supersensitive, causing
individuals to react dramatically to only mild stressors (Vythilingam, et al. 2002).
Pharmacotherapy is a successful treatment method for depressed patients, however, it seems that
for it to be truly effective, it must be paired with psychotherapy (Nemeroff, 1998b). It is said that
psychodynamics may be secondary to neurochemical changes, so all available somatic treatment
modalities must be used simultaneously with psychotherapy (Lesse, 1978; Burnand et. al 2002).
Psychological factors contribute to the psychopathology of depression immensely. The
psychodynamic model is a popular way of understanding depression. Many individuals who are
depressed are self-deprecating, and within this model, Freud observed that this was often the
result of anger turned inward, conceptualizing that this internal rage was because the self was
identifying with the lost object from childhood (1917; 1963). He proposed that melancholic
patients have severe superegos due to their guilt for their aggressive behaviors toward their loved
ones (1923; 1961). Another hypothesis was that losing something that the individual felt was
essential to their self-esteem and having felt helpless in doing anything about it could contribute
to depression, emphasizing that the loss was attached to the individual’s state of well-being
(Sandler & Joffe, 1965). It becomes painfully overwhelming for the person to desire something

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so unattainable. It has also been proposed that depressed patients often live for someone else
rather than for themselves, and when they feel like it is not working out, yet they cannot change
it, they may feel as though life is worthless (Arieti, 1977).
As previously mentioned, relationships are an essential part of life, and Bowlby’s
attachment theory stresses the how important the child’s attachment to the mother is (1969). He
explains that when attachment is disrupted due to parental loss or unstable attachment to the
parent, the child views him or herself as unlovable and feels abandoned by their caregiver
(1969). This is why many children in their adult lives become depressed during an experience of
loss, for it brings these childhood feelings back. The Psychodynamic Theory emphasizes
narcissistic vulnerability and fragile self-esteem in those who are depressed. In addition, it
emphasizes the seeking of a perfectionistic caretaking figure despite being sure that it will not be
found, and idealizing the self or significant other to compensate, leading to disappointment
which then triggers depression and self-devaluation and self-directed anger (Busch et al. 2004).
It has also been found that depression is often present with high comorbidity of other psychiatric
symptoms (Koehler 2015), such as anxiety; for example, too much panic can directly lead to
depression (Panksepp, 2014).
Sociological factors are equally as important to factor in, especially considering that
recent studies show a higher influence of environmental factors than genetic factors (Nemeroff,
2013). In a study done by Kendler and his colleagues, findings showed that the occurrence of
recent stressful events was the highest predictor of a depressive episode, with the influences of
interpersonal relations and temperament characterized by neuroticism trailing closely behind
(1993). In Kendler’s 1995 study, he and his colleagues found that individuals with the highest
genetic risk had a 1.1% probability of becoming majorly depressed, but when exposed to a life

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stressor, the risk increased automatically to 14.6%. Another unique finding was that 1/3 of the
association between life stressors and depression was noncausal because those who were
predisposed to depression actually put themselves into high-risk environments (Kendler et al.
1999). For example, people who have a neurotic temperament may alienate others, which could
cause a break-up (1999). The Psychodynamic Theory holds the belief that stressful life
experiences in childhood such as early losses, abuse, or neglect, lead to a vulnerability to
depression later in life (1999). These negative experiences create a neurobiological sensitivity
that puts individuals at risk to respond to stressors in their adult lives with a depressive episode
(1999). This along with having experienced maternal or paternal separation during their younger
years is one of the strongest risk factors for developing Major Depressive Disorder (Kendler,
1992). One is 10 times more likely to develop this depression in adulthood as a result of negative
relationships and low self-esteem from past abuse or neglect (Bifulco et al. 1998). The
contemporary psychodynamic model of depression also recognizes that these early traumas
cause the child to develop problematic self and object representations (Gabbard, 2014). If
someone were physically or sexually abused, the individual may internalize a bad self, deserving
of this treatment (2000). Klein also credits the desire for triumph as leading to guilt and
depression (1940; 1975).
Adult relational problems are often the result of having grown up around problematic
relationships at a time when the personality was developing (Gabbard, 2014). The adult then has
a hard time forming and maintaining relationships, on top of being especially vulnerable to loss
and narcissistic injury (2014). It is now especially feasible to see why having positive
relationships is so crucial. Along similar lines, a child needs to be raised in a nurturing
environment, in which the caretaker properly “licks and grooms” the child (Fall, 2015). The

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immediate psychosocial environment leads to epigenetic alterations that dictate the child’s ability
to handle stress at the time and as an adult (2015).
Current psychosocial treatments for depression are: Behavior Therapy, Cognitive
Behavioral Therapy, Interpersonal Psychotherapy (EdwardCraighead, Sheets, Brosse, & Ilardi,
2007), and in Jaak Panksepp’s TED Talk he discusses the ideas of deep brain stimulation to
restore enthusiasm for life, (though it cannot yet be easily done in America), as well as the
genetic analysis of PLAY, suggesting that social joy in the brain has yielded a new medicine to
reduce depression by promoting positive feelings (2014). Major Depressive Disorder is clearly
not a one-dimensional mental illness. Biological factors, psychological factors, and sociological
factors all play powerful roles in this pathology, and each individual case is unique. These
factors all relate to one another, and these interactions in and of themselves have strong
influences on the development of MDD. Though a complex disease, it seems that great effort in
research on Major Depressive Disorder continues, and we are lucky that there are many ways to
help a person who is struggling with such a difficult disorder.

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References
Gabbard, G. O. (2014). Psychodynamic psychiatry in clinical practice-fifth edition. Washington
DC: American Psychiatric Publishing.
Koehler, B. (2015). Kagan on Mental Illness. Class notes, NYU, MSW Program.
Koehler, B. (2015, October 2). Neurobiology in mental disorders. Lecture presented at New
York University, New York.
Koehler, B. (2015). Summaries on the effects of childhood maltreatment (e.g., sexual, physical
and emotional abuse and neglect) on the brain and the neurobiological correlates of
resilience.
Nemeroff, C. B. (1998). The neurobiology of depression. SCIENTIFIC AMERICAN-AMERICAN
EDITION-, 278, 42-49.
Panksepp, J. (2014, January 13). The science of emotions: Jaak Panksepp at TEDxRainer [Video
file]. Retrieved from https://www.youtube.com/watch?v=65e2qScV_K8