NEW YORK, Nov. 22, 2016 /PRNewswire/ -- Major depressive disorder (MDD), also known as clinical depression or major depression, is widely recognized as a mood disorder that may lead to a variety of emotional and physical problems. MDD is characterized by persistent feelings of sadness, anger, irritability or frustration, loss of interest in activities, and overeating or loss of appetite that can last from days to months, and alternates with episodes of wellness. Little is known about the etiology of MDD; however, research suggests that there may be combinations of genetic, biological, environmental, and psychological factors that potentially increase the risk of MDD. Epidemiologists forecast that the 12-month total prevalent cases of MDD in the 7MM will increase from 37,157,683 12-month total prevalent cases in 2015 to 38,142,749 12-month total prevalent cases in 2025, at an Annual Growth Rate (AGR) of 0.27%. The US will have the highest number of 12-month total prevalent cases of MDD among the 7MM throughout the forecast period, while Japan will have the least number of 12-month total prevalent cases of MDD. As GlobalData epidemiologists used steady prevalence proportions of MDD over the forecast period, the growth in 12-month total prevalent cases in each market can be attributed to the change in population demographics. GlobalData epidemiologists utilized country-specific and nationally representative peer-reviewed publications to forecast the 12-month total prevalent cases of MDD. The use of consistent methodology across the 7MM allows for a meaningful comparison of the forecast of 12-month total prevalent cases of MDD in these markets. Additionally, the 12-month total prevalent cases of MDD in each of the 7MM are segmented by severity, which can be of importance for predicting the prognosis and course of treatment. Lastly, the 12-month total prevalent cases of MDD in each of the 7MM are further segmented by age and sex in order to provide a more detailed analysis of the patient population.