Biological Causes (Problems in the Brain Structure)
Depression is a medical condition that negatively impacts a person's feelings, thoughts and ability to function day-to-day. While a person suffering from depression typically exhibits abnormal brain chemistry and function, scientists are very cautious in saying whether the depression is caused by or stems from these changes. Those diagnosed with severe illness are far more likely to be depressed than those in otherwise good health, but the depression can be attributed to stress from the diagnosis, rather than biology. This article will list some of the biological causes of depression.
Neurotransmitters.
Brain cells communicate with one another via neurotransmitters, which are chemicals that are emitted whenever we feel an emotion, think or act. The human body is normally very effective in controlling the release of neurotransmitters. About thirty have been positively identified, and clinical depression is associated with a lack of dopamine, norepinephrine, and serotonin. These work in areas of the bran where emotions, stress, sleep, sexuality and appetite are dealt with. Symptoms of depression can include gain/loss of weight, changes in sleep patterns, and loss of interest in socializing or sexual contact.
Medications.
Medicines given for treatment of depression may help to restore the balance of neurotransmitters. For instance, many depressed individuals suffer from low norepinephrine levels; certain antidepressants raise the levels of this neurotransmitter. However, this type of treatment does not work for every depressive episode; some depressed individuals have high levels of certain neurotransmitters.
Stress hormones.
A hormone known as cortisol, the "stress hormone" is emitted by the adrenal glands in response to times of high stress. Cortisol is also referred to as the "fight or flight" hormone, as it tends to increase respiratory rate, heart rate and alertness. In a person with depression, cortisol levels may continue to rise even though they are already high. Cortisol is believed to be linked to depression because in most cases, when it is no longer being secreted, its levels return to normal.
Organ issues.
Because depression is so closely linked to hormone levels, organ diseases can exacerbate the condition. For instance, Cushing's Syndrome is caused by high cortisol levels over a long period of time, and can be initiated via an adrenal tumor. Another condition, Addison's Disease, is caused by adrenal damage (where the glands cannot produce sufficient cortisol). Certain thyroid problems can also cause depressive episodes.