Stress Induced Depression, The New Kid on the Block?

Major depression is a very heterogeneous diagnosis. Subtypes of depression such as melancholic, psychotic or atypical depression may differ not only in etiology and clinical picture, but also in clinical response to medical treatments. Do we need another subtype of depression, what do you think, let me know?

The last decades the working mechanisms of antidepressants haven’t changed very much, hence the name “me too drugs”. Moreover, current antidepressants are based on serendipitous discoveries rather than on bench-to-bedside, targeted drug discovery although clinically efficient antidepressant drugs do exist, the situation is in many cases far from ideal. Existing antidepressants have many shortcomings:

• Low remission and/or high treatment-resistance rates
• Slow onset of action
• Side effects and drug–drug interactions

Wouldn’t it be nice if we had neurological, biological, and genetic data in future DSM classifications of Major Depression?

The current diagnostic criteria in the DSM classification systems represent clusters of symptoms and characteristics of clinical courses that do not necessarily describe homogeneous disorders and may rather reflect common final pathways of different pathological processes.

Arguments that stress plays an important role in the development of depression

• Increasing evidences report gene environment effect in Major Depression, with stress often representing the key environmental trigger of MD onset in vulnerable individuals
• Hypothalamo–pituitary–adrenocortical (HPA)-axis dysregulation due to chronic stress is confirmed to be an important parameter for treatment outcome in MD but it is neither a necessary nor a sufficient determinant for acute treatment response
• Stress exposure conceivably plays a causal role in the etiology of MD and depression-like disorders. Neurotransmitters and neuropeptides, as well as conceptually novel immune and inflammatory mediators, are likely intermediate links between stress exposure, depressive symptoms, and MD
• Animal models involving a chronic (i.e., continuous exposure to a threatening stimulus for a significant amount of time, usually weeks) or intermittent (i.e., daily short exposure to a threat for subsequent days) exposure to negative stressful events can be considered the most effective in modeling MD-associated behavioral and physiological disturbances. Also animal models in which the threatening stimulus is social in nature or models in which exposure to stressful stimuli occurs in the early postnatal or juvenile age are effective models for MD behavior in animals
• Recently identification of genes overexpressed or downregulated in selected brain regions after chronic stress exposure are linked to major depression.

Stress Induced Depression is an entity developed by Swedish researchers.

A dramatic increase in the number of workers on longterm sick leave was observed between the years 1997 and 2003 (Statistics Sweden, 2004 ). Studies of consecutive cases with psychiatric diagnoses culled from the databases of two large Swedish insurance companies showed that about 80% of patients met DSM-IV criteria for MD

Characteristics of Stress Induced Depression:

• The depression episodes were mild to moderate, and accompanied by significant working memory impairment.
• It tended to have a prolonged course, and that the patients often remained in a state of exhaustion after the depressive symptoms had remitted. the remaining clinical picture was one of deep mental and physical fatigue, disturbed and non-restorative sleep, irritability, perceptual hypersensitivity, emotional liability, and pronounced cognitive disturbances (mainly memory and concentration problems).
• The majority was clearly induced by psychosocial stress, either at the workplace or often in combination with stress factors in the family.
• In contrast to other kind of depression the HPA-axis hypo-reactivity was found in STRID patients.

This is one article of a special issue of PLoS ONE about Stress-Induced Depression and Comorbidities: From Bench to Bedside

Other related posts on this blog:

Neurobiology of psychosocial stress and depression

How can Genes and Stress cause depression?

Recurrence of depression with less stress than the first episode

Alessandro Bartolomucci, Rosario Leopardi (2009). Stress and Depression: Preclinical Research and Clinical Implications PLoS ONE, 4 (1) DOI: 10.1371/journal.pone.0004265