No one knows exactly what causes it, but it can occur for a variety of reasons. Some people experience depression during a serious medical illness. A loss of interest in activities or feeling sad and down are symptoms that characterize this condition. A person with depression cannot simply snap out of itit is a medical condition that affects your quality of life. Depression can also lead to suicide, particularly if left untreated, and you are more likely to develop a physical illness if you have depression. The good news is that, in most cases, depression is treatable in older adults. The causes and risk factors for depression in adults are complex and not fully understood. Researchers suggest that an adults vulnerability to depression arises out of both genetic and environmental factors. When depression occurs in men, it may be masked by unhealthy coping behavior. For a number of reasons, male depression often goes undiagnosed and can have devastating consequences when it goes untreated. American psychiatric association practice guideline for the treatment of patients with major depression, 2000. It is a common but serious mood disorder that needs treatment. It causes severe symptoms that affect how you feel, think, and handle daily activities, such as sleeping, eating, and working.