For a long time psychiatrists and psychologists have lumped such triggers together under rather vague umbrella terms, including “severe psychosocial stressors” and “stressful life events.” In recent years, however, a few researchers have looked more carefully at the different kinds of events that provoke a depressive episode. The evidence they have collected so far argues for a more nuanced understanding of how stress interacts with individual susceptibility to depression, how quickly depression follows different types of stress, and how best to treat depression in these various situations.
An event that catalyzes a depressive episode does not have to be catastrophic—sometimes what seems like mild stress or a minor loss to most people is enough to plunge someone into murky misery that refuses to fade. It all depends on an individual’s vulnerability to depression, which is determined by a complex interaction of many different factors, including: sources of stress in one’s life; family history of mental illness; cognitive style—that is, the patterns of thought unique to an individual; and psychosocial factors, such as adversity in early childhood and the presence or absence of caring relatives and friends. Someone with low vulnerability and no previous depressive episodes may survive a devastating hurricane or emerge from a period of grief following the death of a sibling having never experienced true depression. In contrast, someone at high risk of depression with little social support might fall into the depths of despair for months on end after a budding romance wilts and withers.
[P]eople who lose important relationships early on—through the death of a parent, for example—may become especially sensitive to even small losses in the future, especially interpersonal losses.
[T]he deliberate rejection of one person by another—a form of interpersonal loss known as “targeted rejection”—is a particularly powerful catalyst of depression.
When a patient shows symptoms of depression soon after a loss—whether the death of a spouse or a failed romance—clinicians face a dilemma: They must determine whether the patient is heading toward or has already developed true depression or, instead, whether the patient is passing through a phase of typical grief. Weighing factors such as changes in self-esteem and family history of mental illness can help clinicians make an informed evaluation in many cases, but some situations are more ambiguous. Psychiatry has no universal litmus test for depression.
More effective treatments will likely require a much clearer understanding of exactly what happens in the brain and body during depression. […] “At the end of the day, it’s not stressful events alone that result in depression,” Slavich says. “It’s about the differences in how our brains construe those types of events. All the stress we experience gets translated into the types of biological and cognitive processes that precipitate depression. Some people ruminate about them and others don’t. Some people may never develop depression, no matter how badly they are rejected. That’s the silver lining—although we can’t always control whether someone dies or whether our girlfriend breaks up with us, we can try to control how we think about it and deal with it.”