According to The Diagnostic and Statistical Manual of Mental Disorders (4th edition—DSM-IV), Major Depressive Disorder (MDD) is characterized by a depressed mood for a large portion of the day, and occurs almost every day. There is a noticeably decreased interest or pleasure in more or less all activities (anhedonia). Some of the symptoms vary from person to person. For example, patients may experience a dramatic increase or decrease in weight and appetite may either increase or decrease. In addition, there can be a lack of sleep (insomnia) or over-sleeping (hypersomnia), and psychomotor retardation or agitation. Persons suffering from MDD are usually very lacking in energy, feel worthless and are unable to focus. They are also …show more content…
The diagnosis of major depressive disorder requires a distinct change of mood, characterized by sadness or irritability and accompanied by at least several psychophysiological changes, such as disturbances in sleep, appetite, or sexual desire; constipation; loss of the ability to experience pleasure in work or with friends; crying; suicidal thoughts; and slowing of speech and action.” For MDD to be diagnosed, these symptoms should persist for over 2 weeks and must also have a major negative effect on regular activities, including work and family …show more content…
Another hypothesis of the biochemical theory postulates the involvement of noradrenaline, dopamine and serotonin based on discoveries that both tricyclic antidepressants and monoamine oxidase inhibitors led to an increase in the monoamine neurotransmitters and specific sites in the brain (Pratt, 2011). Studies have also shown that reserpine which is utilized as an antihypertensive agent, was able to decrease the monoamine neurotransmitters as well as induce major depressive