¶ … Depression is a state of sadness and gloom where one feels dull and overwhelmed by the challenges of life. People tend to say that they are "depressed' any time they feel very unhappy. More likely than not, it could just be a mere response to fatigue, sad thoughts or events. This improper use of this term causes confusion between an ordinary mood swing and a medical condition. While it is normal for all human beings to experience dejection every now and then, a few people may experience unipolar depression. Ordinary dejection is rarely serious enough to significantly affect a person's day to day activities and does not persist for long. Mood downcasts can even have some benefits. Time spent contemplating can help an individual explore their inner self, values and way of life. They often come out of it feeling stronger, resolved and with a greater sense of clarity. Unlike normal dejection, clinical depression does not have any characteristics of redemption. It causes severe and persistent psychological pain that can get worse with time. The victims may find that they have no will to do simple activities in life; the will to live is lost in some cases (Comer, 2013).

Behaviors Associated with Depression

Different people may have different forms of depression. Most of the victims feel dejected and melancholic. They describe how they feel with words such as "empty", "humiliated" or "miserable". The sense of humor is often lost, depressed persons rarely get pleasure from any activity, and in some cases, they display the inability to feel pleasure (anhedonia). Several of them experience anger, agitation or anxiety. This immense misery may cause crying spells (Comer, 2013).

People suffering from depression tend to lose the desire to engage in their normal activities. A majority of them report to have lost their drive, spontaneity and initiative. They may find that they have to push themselves to work, obey meals, have sex or even chat with friends. This is a state known as "paralysis of will". Victims of depression are not usually very active or productive. They spend more time with no company and may be in bed for extended periods. They hold very negative opinions about themselves. They tend to consider themselves inferior, undesirable, inadequate and even evil. They also lay the blame for almost all unfortunate events on themselves even when they are not responsible in any way and seldom take credit for their positive achievements.

Pessimism is another cognitive sign of depression. Victims tend to be convinced that things can never get better and feel like they cannot change anything in their lives. Since they expect a negative outcome, they are more likely to fall into procrastination. They are vulnerable to suicidal thoughts due to the sense of helplessness and lack of hope (Wilson & Deane, 2010).

Depressed people tend to claim that they have poor intellectual abilities. They lack focus, feel confused, have poor memory and lack the ability to solve some basic problems. In studies carried out in laboratories, people with depression perform poorly on tasks requiring reasoning, attention and memory as compared...

However, it is possible that these challenges are not a reflection of cognitive problems but those related to motivation (Hammar et al., 2011).
Depressed persons frequently suffer from physical illnesses such as indigestion, headache, dizziness, general pain and constipation. As a matter of fact, numerous depressions are at first misdiagnosed as a medical problem. Sleep and appetite problems are particularly common. A majority of depressed people report feeling more fatigued, and eating and sleeping less than they did before. However, there are some who sleep and eat excessively.

Biological Influences on Depression

According to studies conducted on biochemical, anatomical, genetic and immune systems, it is evident that biological factors have an influence on depression. Four different researches -- molecular biology gene studies, adoption, twin and family pedigree -- suggest that there are people who have an inherited depression predisposition (Elder &Mosack, 2011). Family pedigree studies pick individuals who are depressed as probands (people who are the main focus in a genetic study), conduct examinations on their relatives and find out whether there are other family members who suffer from depression. If the unipolar depression predisposition is hereditary, the relatives of a proband have a higher chance of getting depression than the general public. According to researchers, up to 20% of the victim's relatives have depression as compared to only 10% of the population. If a monozygotic twin becomes depressed, the other twin has a 46% chance of having depression. Contrary to this, when a dizygotic (fraternal) twin has depression, there is only a 20% chance of the other twin developing depression (Comer, 2013).

Adoption studies also imply that there are genetic factors involved, at least in severe depression cases. A study in Denmark examined families with adopted children who had been hospitalized because of depression. It turned out that the adoptees' biological parents have a higher chance of developing severe (but not mild) depression than the biological parents of adoptees who are not depressed. These findings are interpreted by some theorists to mean that genetic factors are more likely to cause severe depression than mild depression.

There is a strong connection between depression and the low activity of serotonin and norepinephrine (neurotransmitter chemicals). It was believed that the low activity of any of these two chemicals could lead to depression for many years, but investigators have found that there is a more complicated relationship (Goldstein, Potter, Ciraulo, & Shader, 2010). According to research, the interaction between the activity norepinephrine and serotonin or between these neurotransmitters and other neurotransmitters present in the brain may be responsible for unipolar depression as opposed to the operation of one neurotransmitter alone. For instance, some studies suggest that there is an imbalance in dopamine, serotonin, acetylcholine and norepinephrine neurotransmitter activity in people who have depression. Some researchers, in this theory's variation,…