2012年7月22日 星期日

Depression (Major Depressive Disorder)


Depression affects millions of people worldwide and is characterized by feelings of sad mood, hopelessness, irritability, fatigue and loss of interest in once pleasurable activities. Depression symptoms vary from person to person, but many people who are feeling down for more than several weeks, may be clinically depressed.

What are the symptoms of depression?


Persistent low or sad mood
Feelings of anxiety
Lack of energy / fatigue
Feelings of guilt, hopelessness
Loss of interest in activities that were once enjoyable
Irritable mood
Changes in appetite
Changes in sleep: either insomnia or over-sleeping
Difficulty concentrating or remembering things
Aches or pains, digestive problems, persistent headaches
Thoughts of suicide

Depression occurs more frequently in women than in men, perhaps because of biological factors unique to women may be linked to a higher depression rate in women. Women also tend to complain of depression symptoms differently than men.

The majority of depressed patients never seek help, although depression is highly treatable. Many depressed patients share the mistaken belief that other people will think less of them if they go to a doctor for depression. Many blame the symptoms on other diseases and never seek help. Some people with depression have suicidal thoughts in the belief that their feelings will never change.

Depression can be caused by a combination of factors, including genetics, environmental factors, trauma and stress. Whatever the cause, more precisely an imbalance of neurotransmitters that carry signals between nerves.

The monoamine hypothesis

Most antidepressants on the market today treat depression by increasing the availability of monoamine neurotransmitters, nor-epinephrine and serotonin. Some antidepressants may also increase another monoamine, dopamine. Although the monoamine hypothesis has been the focus of much antidepressant research, it has also received a share of criticism. Some antidepressant drugs work well in depressed patients despite the fact that they do not work through the monoamine pathway. Also, experiments in which monoamines were depleted in patients did not seem to cause depression in healthy people and did not make depression worse in depressed patients.

Modern antidepressant drugs work by blocking the re-uptake of monoamines from the synapse (gaps between nerve endings). This causes the monoamines to stay in the synapse longer, prolonging the signal transfer between nerve cells.

In the past, depression was often treated with tricyclic compounds or with monoamine oxidase (enzymes that break down monoamines) inhibitors. Monoamine oxidase inhibitors are not used very often anymore, since they require the patient to follow a strict low histamine and low tyramine diet to prevent a potential hypertensive crisis.




The author is senior editor for reverta.com. Visit Reverta's website to learn more about depression or read more about alternative depression treatments.





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