Association between Stress and Depression

| June 30, 2012

The relationship between stress and depression is bidirectional. Stress contributes to the development of depression and depression facilitates interpreting life events as stressful. There are certain attributes in the stressful event that determine the development and severity of depression. The intensity and the frequency of the unpleasant event affect the likelihood of depression. The first three to six months, particularly the first four weeks, are the most vulnerable period for the development of a depressive episode. The content of the event mostly involves some kind of loss, for example interpersonal loss (death of a loved one or break- up of a relationship) or loss of self-esteem. An adversity that was influenced by the individual might lead to a more severe form of depression than an occurrence in which the individual did not have any role.
Some researchers argue that there is a difference between the effect of stressful life events on the first and on the subsequent depressive episodes .They propose that stress plays a more significant role in giving rise to the first episode rather than the following episodes. Thus, the subsequent episodes can occur spontaneously or without any apparent stressful precursor. This idea is reflected in the kindling theory, which suggests that the individual becomes so sensitized to depression that even minor events can cause depression.
Despite the above proposed correlations between stress and depression, the exact mechanisms mediating these associations are to be investigated. There is some evidence suggesting that biological processes associated with stressful events such as increased cortisol levels, may cause changes in the brain structures and lead to depression. Some authors propose that encountering stressful situations in childhood may predispose the individual to adulthood depression. Others blame negative interpretation of stressful events for the genesis of depression, whereas some researchers emphasize the role of gender (more depression in females due to such factors as sexual abuse and poor income) in the development of depression. In sum, an eclectic approach that takes into account several causative influences might be more justifiable.
Reciprocally, depression can foster exposure to stressful life events. The term stress generation is used to indicate that depressed people have more prone to encounter undesirable events, which may be due to troublesome family environments, their tendency to trigger relationship difficulties or attributing negative reappraisals to life events.
It should be noted, however, that depression is not the only sequel of stressful life events. There are multiple adverse consequences that result from stress. Among them are acute stress disorder (ASD), post traumatic stress disorder (PTSD) and adjustment disorder. Acute stress disorder refers to the reaction of the individual to a traumatic event within the first month. This reaction lasts from two days to four weeks and includes re-experiencing the event (in the form of intrusive thoughts or images, dreams, flashback episodes), hyper arousal (nervousness, vigilance, exaggerated startle response, difficulty falling asleep, concentration problem) and avoidance of the event (avoiding mentioning the event in conversations and avoiding people or places that remind the event) and numbing of emotions (inability to love, forgetting certain aspects of the event). In addition the symptoms cause significant distress and impairment in social and academic functioning. PTSD has a similar symptom profile, however, it is distinguished from ASD by its duration which is more than one month. In addition, the nature of the event is important in the above two disorders, such that the event should involve threatened or actual death or serious injury. In adjustment disorder, the individual suffers from emotional (depression, anxiety) or behavioral (conduct disorder) problems within three months following a stressful event.
In conclusion, stress predisposes the individual to depression (as well as multiple other disorders including ASD, PTSD and adjustment disorder) and depression gives rise to more stressful life events. Given the pervasive nature of adverse events in everyday life, employment of adaptive coping mechanisms may help to prevent the genesis of a disequilibrium and development of psycho-pathologies.

Source
American Psychiatric Association (2000). Diagnostic and statistical manual of mental
disorders (4th ed., text rev.). Washington, DC: Author.
Kessler, R.C.(1997.The effects of stressful life events on depression. Annual Rev
Psychol,48, 191–214.