The management of depression involves a number of different pharmacological, behavioral, and medical device-based therapies. Major depressive disorder, often referred to simply as "depression", is diagnosed more frequently in developed countries, where up to 20% of the population is affected at some stage of their lives. According to WHO (World Health Organization), depression is currently fourth among the top 10 leading causes of the global burden of disease; it is predicted that by the year 2020, depression will be ranked second.