High-functioning depression is a real thing, and it can have serious consequences if not addressed and treated. The diagnosis for high-functioning depression is officially called persistent depressive disorder, or PDD. Someone struggling with PDD experiences many of the symptoms of depression, but less severely. This allows the person to be able to function mostly normally, going to work or school, performing well, keeping up with responsibilities at home, and engaging in most social activities.
This type of depression can be difficult to detect in oneself, but especially in others. To the outside world, a person with PDD seems fine. Internally that person is struggling. High-functioning depression may not seem as serious as major depression, but it should be diagnosed and treated. Living with PDD can be a struggle and lowers quality of life, but treatment and self-management can help.