Depression Research at NIMH - Stress and Depression

Written by NIMH

Stress and Depression

Psychosocial and environmental stressors are known risk factors for depression. NIMH research has shown that stress in the form of loss, especially death of close family members or friends, can trigger depression in vulnerable individuals. Genetics research indicates that environmental stressors interact with depression vulnerability genes to increase the risk of developing depressive illness. Stressful life events may contribute to recurrent episodes of depression in some individuals, while in others depression recurrences may develop without identifiable triggers.

Other NIMH research indicates that stressors in the form of social isolation or early-life deprivation may lead to permanent changes in brain function that increase susceptibility to depressive symptoms.

Brain Imaging

Recent advances in brain imaging technologies are allowing scientists to examine the brain in living people with more clarity than ever before. Functional magnetic resonance imaging (fMRI), a safe, noninvasive method for viewing brain structure and function simultaneously, is one new technique that NIMH researchers are using to study the brains of individuals with and without mental disorders. This technique will enable scientists to evaluate the effects of a variety of treatments on the brain and to associate these effects with clinical outcome.

Brain imaging findings may help direct the search for microscopic abnormalities in brain structure and function responsible for mental disorders. Ultimately, imaging technologies may serve as tools for early diagnosis and subtyping of depression and other mental disorders, thus advancing the development of new treatments and evaluation of their effects.

Hormonal Abnormalities

The hormonal system that regulates the body's response to stress, the hypothalamic-pituitary-adrenal (HPA) axis, is overactive in many patients with depression, and NIMH researchers are investigating whether this phenomenon contributes to the development of the illness.

The hypothalamus, the brain region responsible for managing hormone release from glands throughout the body, increases production of a substance called corticotropin releasing factor (CRF) when a threat to physical or psychological well-being is detected. Elevated levels and effects of CRF lead to increased hormone secretion by the pituitary and adrenal glands which prepares the body for defensive action. The body's responses include reduced appetite, decreased sex drive, and heightened alertness. NIMH research suggests that persistent overactivation of this hormonal system may lay the groundwork for depression. The elevated CRF levels detectable in depressed patients are reduced by treatment with antidepressant drugs or ECT, and this reduction corresponds to improvement in depressive symptoms.

NIMH scientists are investigating how and whether the hormonal research findings fit together with the discoveries from genetics research and monoamine studies.

Co-occurrence of Depression and Anxiety Disorders

NIMH research has revealed that depression often co-exists with anxiety disorders (panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, or generalized anxiety disorder). In such cases, it is important that depression and each co-occurring illness be diagnosed and treated.

everal studies have shown an increased risk of suicide attempts in people with co-occurring depression and panic disorder - the anxiety disorder characterized by unexpected and repeated episodes of intense fear and physical symptoms, including chest pain, dizziness, and shortness of breath.

Rates of depression are especially high in people with post-traumatic stress disorder (PTSD), a debilitating condition that can occur after exposure to a terrifying event or ordeal in which grave physical harm occurred or was threatened. In one study supported by NIMH, more than 40 percent of patients with PTSD had depression when evaluated both at one month and four months following the traumatic event.

Co-occurrence of Depression and Other Illnesses

Depression frequently co-occurs with a variety of other physical illnesses, including heart disease, stroke, cancer, and diabetes, and also can increase the risk for subsequent physical illness, disability, and premature death. Depression in the context of physical illness, however, is often unrecognized and untreated. Furthermore, depression can impair the ability to seek and stay on treatment for other medical illnesses. NIMH research suggests that early diagnosis and treatment of depression in patients with other physical illnesses may help improve overall health outcome.