Depression can occur at any time, but on average, it first appears during the late teens to mid-20s. Women are more likely than men to experience depression. Some studies show that one-third of women will experience a major depressive episode in their lifetime. There is a high degree of heritability (approximately 40%) when first-degree relatives (parents/children/siblings) have depression.
Depression (major depressive disorder) is a common and serious medical illness that negatively affects how you feel, think, and act. Fortunately, it is also treatable. Depression causes sadness and a loss of interest in activities you once enjoyed. It can lead to various emotional and physical problems and decrease your ability to function at work and home. Depression is among the most treatable mental
disorders. Between 80% and 90% of people with depression eventually respond well to treatment. Almost all patients gain some relief from their symptoms.
If you've been treated for depression, but your symptoms haven't improved, you may have treatment-resistant depression. Taking an antidepressant or going to psychological counseling (psychotherapy) eases depression symptoms for most people. But with treatment-resistant depression, standard treatments aren't enough. They may not help much at all, or your symptoms may improve only to return. Treatment-resistant depression symptoms can range from mild to severe and may require several approaches to identify what helps.