Depressive disorders are common mental disorders that impair individual’s normal life. They are characterized by persistent feeling of sadness, loss of interest or enjoyment, loss of self-worth or guilty feeling, sleep or eating disorders, fatigue, inattention or concentration problem.
Major Depression Disorder (MDD)
Major depression disorder (MDD) or depressive episode is a subcategory of depressive disorders that also called as unipolar depression or clinical depression or simply depression. Major Depression Disorder is categorized as mild, moderate or severe.
These symptoms should persist for at least two weeks, disrupt the daily life including social, occupational and educational activities, not following a medication or physical illness, and cannot be attributed to the mourning of a loss of a loved one. The diagnosis is based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), with a minimum one major depressive episode without a history of mania or hypomanic or mixed episodes.
Manic episode is an emotional state for a period of at least one week characterized by high mood and energy associated with increased activity decreased need for sleep and speech pressure. The hypomanic episode is the same as the manic with a shorter period (for minimum 4 days and less than a week). The mixed episode is the simultaneous presence of symptoms of depression and mania at the same time. The prevalence of mental disorders is predicted to increase by aging world population.
On the other hand, the response rate to classic psychiatric treatment is insufficient. Clinical, pharmacological, pharmacokinetics and pharmacodynamics factors may involve in resistance to psychotherapeutic drugs. In addition to these factors, recent animal findings suggest that abnormal microbiome can possibly change the behaviors and drug metabolism of the host, which may explain the ineffectiveness and other side effects of psychiatric drugs. Modern lifestyle, such as antimicrobial medication, vaccination, widely used disinfectant cleaning and dietary changes, have deep and lasting effects on the human microbiome.
Epidemiology of Major Depression Disorder in the World
MDD affects one in four to six people during some point of life and can start almost at any age but often in youth. It may occur once or reoccur in a person’s life while the rate of relapse is high. Major depression in 20% of the patients tends to become chronic which defines as lasting for minimum two years. The more episodes a patient experiences, the shorter the time between relapses and the more severe the depression is.
WHO for 20th anniversary of “World Mental Health Day” occasion on October 10, to draw attention of governments and society to address depression as a global and also treatable illness, prepared a report as “Depression: A Global Crisis” as the theme for the year 2012–2013. In this report depression was listed as the third leading cause of the GBD in 2004 and will be the first by 2030.
Lifetime prevalence estimates were between 3-16 %, while Japan had the lowest rates; USA was at the top of the list. It was also stated that 20% of the mental disorder comorbidities in Europe are caused by depression and this rate is as high as 26% in some other countries. Major Depression Disorder is the most commonly seen mental disorder in Europe and 11% of EU citizens have depression in some points of their life. Prevalence of MDD in 2015 has been reported to be 4.4% which means 350 million people in the world have depression.
MDD is more prevalent in women (5.1%) than men (3.6%). According to the GBD report of World Health Organization, Major Depression Disorder has been listed as the fourth leading cause of disability in 2000, however in the latest update report, it has moved up in the ranking to third place in the world and first place in middle- and high-income countries. The annual incidence of MDD was estimated to be 3.2% in men and 4.9% in women.