Depression is a normal reaction to grievous loss. However, some people have a tendency to suffer depression out of proportion to what could be expected. Clinical depression refers to a profound and persistent state of sadness or despair and / or a loss of interest, often accompanied by disturbances of sleep, energy, appetite, concentration and libido. Depression may arise following stressful life events (reactive depression), however, most often it arises without detectable external influences (endogenous depression).
There are two main types of depression. The first is major depressive disorder, which is a moderate to severe episode of depression lasting two or more weeks. In children this may appear more as irritability. The second, dysthymic disorder, is an ongoing, chronic depression that lasts two or more years (one or more years in children), and has an average duration of 16 years. This depression is mild to moderate, has a gradual onset, and may rise and fall in intensity. Patients with this disorder may experience up to 2 months normal mood at various times.
What causes depression?
WHO has estimated that in this new century major depression will be one of the most important causes of ill health overall. Whereas the cause of depression is still obscure, it is becoming clear that a number of diverse factors are likely to be implicated, both genetic and environmental.
Studies have shown that depression is more likely in individuals who have a biological relative, that is depressed. Evidence that depression is a biological disorder, is supported by the fact that, there are bodily symptoms and that certain illnesses can cause depression.
Research indicates that low levels of neurotransmitter (chemicals which carry signals from one nerve cell to another) activity, particularly norepinephrine and serotonin in the brain, are the biological cause of the disorder. These neurotransmitters are involved in the functioning of the hypothalamus, which helps to regulate sleep, appetite, sexuality and physical movement. Conversely, psychodynamic theorists identify unconscious processes as important psychological mechanisms in depression. Freud proposed that depression is anger directed against the self.
Reinforcement theories attribute depression to low levels of reward in an individual’s environment, and according to the theory of learned helplessness, depression could be a person’s inevitable reaction to uncontrollable events. Finally, cognitive theory states that depression is less a disorder of mood than of thought: depressed people think about themselves, the world and the future in very negative terms, these then create a negative mood. However, critics of this theory suggest that negative cognition is the result of depression, not the cause of it.
Symptoms of depression
There are a number of signs and symptoms of depression, and the more that are present, the more severe the disorder. Some examples are given below:
- Emotional – depressed mood.
- Motivational – loss of interest or pleasure in activities.
- Physiological – weight loss or gain, sleep disturbances, constipation, backache, anorexia, fatigue or loss of energy
- Behavioral – restlessness or sluggishness.
- Cognitive – feelings of worthlessness, excessive guilt, decreased ability to concentrate, recurrent thoughts of death.
Less overt physiological symptoms of depression involve its effect on the immune system. Depression is associated with its poor functioning. Biochemical evidence for this longstanding observation has come from research that has shown that depression often results in increased secretion of the hormone cortisol from the adrenal glands, which may mediate impaired immunological functioning.