Helen M. Farrell talks about depression and what it is:

Depression is the leading cause of disability in the world. In the US, close to 10% of adults suffer from this. But, since it is a mental illness, it can be harder to understand say compared to high blood pressure. A big source of confusion is difficulty differentiating depression from and feeling sad. Almost everyone feels down from time to time. Getting a bad grade, losing a job, having an argument, even a rainy day can bring on feelings of sadness. Sometimes there is no trigger at all and it shows up out of the blue. Then circumstances change and the sad feelings disappear.

Clinical depression on the other hand, is a medical disorder. It won’t go away because you want it to and it lingers for at least two weeks. In some cases even years. It interferes with daily life, such as one’s ability to work, play, or love. Depression can have a variety symptoms which include a low mood, loss of interest, appetite changes, feeling worthless or overly guilty, sleeping too much or too little, poor concentration, restlessness or slowness, loss of energy, eating too much or too little, or recurrent thoughts of suicide. If you have at least 5 of these symptoms, according to psychiatric guidelines, you qualify for a diagnosis of depression.

It goes beyond behavioral symptoms. There are physical manifestations within the brain. These changes can be seen with the naked eye and medical imaging. Volumes of the frontal lobes and hippocampus are actually smaller. Microscopically, there is the abnormal transmission or deficiency of certain neurotransmitters (especially serotonin, norepinephrine, and dopamine), changes in the circadian rhythm (especially in REM with depressed individuals spending too much time in REM and changes in the slow-wave parts of the sleep cycle), and endocrine changes (such as high cortisol and dysregulation of thyroid function). However, still much work is to be done to get a complete picture of the causes of depression. It seems to be quite a complex interaction between genetic predisposition and the environment.

Don’t wait any longer to look for help. According to the National Institute of Mental Illness, it takes the average person with mental illness 10 years to ask for help. But there are effective treatments. Medication and therapy work synergistically to enhance one’s neurochemistry. In more stubborn cases, electroconvulsive therapy, which generates a controlled seizure under anesthesia is highly effective and well tolerated. In addition, TMS is also a great outpatient treatment offered. If you know someone who struggles with depression, show your support and gently encourage them to look for the care they deserve. You can even offer to help with specific tasks and looking for providers in the area or setting up an appointment. To someone with depression, those first steps can seem insurmountable. If they feel guilty or ashamed, reassure them that this is a medical condition. If you have not experienced depression yourself, avoid comparing it to times that you felt down. This can make someone feel guilty for struggling. Even talking about depression openly can help. For example, asking someone about suicidal thoughts can actually reduce suicide risk as evidenced by the literature. The open discussion can erode stigma and make it easier to seek help.