An overview of depression-related content on Genes to Cognition Online.

A major depressive episode includes an extended low mood most of the day or loss of interest/pleasure, which may be accompanied by symptoms such as weight loss, fatigue, sleep disturbance, and suicide ideation. There is strong evidence that depression is a genetic disorder, with BDNF and the serotonin transporter gene some of the candidate genes. A seminal study by Caspi and colleagues (2003) shows how the serotonin transporter gene can interact with the environment to cause depression. Serotonin is associated with suicide, aggression, and impulsivity and selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat depression. On the cellular level, glial cells called oligodendrocytes have been found to be decreased in individuals with depression and bipolar disorder. A network of brain areas, including the cingulated gyrus, hypothalamus, brainstem, and amygdala, has been associated with depression. Deep-brain stimulation can dramatically reduce the symptoms of depression. GENES Advances in genomic technology have added considerable power to the search for candidate genes for depression. Ironically, this has led to an increasingly complex picture, which is due to different forms of the disorder and environmental interactions. A study by Caspi and colleagues indicate an intriguing dynamic between serotonin transporters and the environment. Use the chromosome Map of Disorders and Processes to explore this and other candidate genes. BIOCHEMICALS People who commit suicidal acts and people who commit aggressive acts and people who commit impulsive acts have been shown to have elevated levels of serotonin, irrespective of their mood state. Selective serotonin reuptake inhibitors (SSRIs) were developed to increase serotonin levels to treat depression and self harm, and are discussed by Professor James Potash in a series of illuminating interviews. Other biochemicals associated with depression include glutamate and norepinephrine (noradrenalin). CELLS Post-mortem studies of depression have commonly shown has been that glial cells called oligodendrocytes are decreased. Glial cells have vital roles in brain function, which include supporting a network across brain systems. This may interfere with a brain circuit involved in maintaining the balance between the normal responses to stressful or anxiety-provoking events. Professor Wayne Drevets discusses this hypothesis in Brain Cells and Depression/Bipolar Disorder. BRAIN In the Neuropathology of Depression, Professor Helen Mayberg discusses brain correlates of depression in the cingulate area, the hypothalamus, the brainstem and the amygdale. Professor Mayberg has pioneered a technique called Deep Brain Stimulation, which has been remarkably affective in treating depression. In a series of video clips, Doctor Jon Lieberman discusses his experiences as a patient who has received Deep Brain Stimulation. COGNITION The Dana review text article, Background to Depression, provides a comprehensive overview of the key statistics relevant to depression, including causes, treatments. Approximately 5 to 7% of the adult population of the United States will suffer from a form of depression during any year, and the lifetime risk may exceed 15 percent. In Experiencing Depression, Doctor Jon Lieberman describes his personal how depression has affected his life as an overwhelming sense of apathy, incompetence and severe, intense anxiety. ENVIRONMENT In Stressors and the Environment Cause, Professor Wayne Drevets discusses how the early onset form of depression has been associated with stressful situations. These can include both social stressors like physical or sexual abuse, or physiological stressors like medical illness or it can include stressful situations arising with just repetitive stress like bullying or perhaps even family stress or job stress. In Gene-Environment Interactions, Professor Helen Mayberg discusses how the serotonin transporter gene has been shown to interact with a stressful/abusive environment to produce depression.

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