Depression (major depressive disorder or clinical depression) is a common mood disorder that can cause serious consequences. Depression is defined as a medical condition that lasts for more than 2 consecutive weeks including sadness, loss of interest, changes in appetite, sleeping problems, fatigue, purposeless physical activity or slowed movements, feeling worthless or guilty, difficulty thinking and thoughts of suicide. It is distinguished from temporal fluctuations of natural emotions, or from the challenges experienced in everyday life .
Environmental, psychological, and genetic factors may all be involved in complex interactions which can result in depression . Depression is more likely to occur if there has been a recent life changing event, family history, prescribed medication, or a health problem. Individuals who take illegal drugs are more prone to depression than people who do not.
Globally, depression has been reported to have affected more than 300 million people. The World Health Organization reports that depression is the leading cause of disability as measured by years lived with disability, and the 4th leading contributor to the global burden of disease . In 2015, depression was a top cause of age-specific disability-adjusted life year (3rd in age category 15–19 years, 2nd in 20–24 years old, 4th in 25–39 years old, 5th in 40–44 years old, and 6th in 45–54 years old) .
Depression is also reported to be associated with suicide. It is believed that 50% of all suicides are related to depression , and 2% to 9% , or 15%  of people diagnosed or treated with depression will die from suicide. It is also known that depression is a contributing factor to the prognosis of chronic diseases. According to Moussavi et al , some depression had adverse effects on health scores rather than on chronic disease, and depression and chronic illness together showed a worse health outcome than any other combination of chronic diseases.
Over the last 50 years, Korea has undergone unprecedented economic growth and changes in social values. As a result, mental health problems have become a national issue. Korea has the 2nd highest suicide mortality rate (25.8 per 100,000 population) out of the country members within the Organisation for Economic Co-operation and Development . An epidemiological survey on mental health conducted every 5 years reported a gradual increase in the prevalence of depression (2001, 4.0%; 2006, 5.6%; 2011, 6.7%) [10,11]. A cluster randomized trial study conducted in Philadelphia, USA reported that the greening of vacant land showed a positive effect on the mental health of residents . This suggests that mental health may be improved by community specific policy efforts to improve the local environment. Based upon this evidence, data from national and regional surveys of mental health status will aid mental health policy design.
The current issue of Osong Public Health and Research Perspectives includes a study of “Regional differences of mental health status and associated factors: based on the community health survey “. This study  used data obtained from the 2016 Community Health Survey (CHS). CHS was performed by the Korea Centers for Disease Control and Prevention (KCDC) and contained data from 224,421 people who over 19 years of age . Lim  showed independent lifestyle and health status variables had statistically significant effects on stress or depression and found associations of several risk factors with depression in both urban and rural areas. These data are expected to be used for establishing mental health policies according to local characteristics.