Sometimes referred to as: low mood, dysthymia, postpartum depression, premenstrual dysphoric disorder, seasonal affective disorder, manic depression, clinical depression

Interview between:

  • Andrew Cunningham, MD

  • Nora Lansen, MD

Depression is a mental health disorder that manifests as extended periods of low mood and other symptoms that interfere with daily activities.

Cases Per Year (US)

17 million

General Frequency

7% of adults


Depression can happen to anyone, but certain factors elevate risk, such as family history of depression, a significant life event, late age, poor social support, low socioeconomic status, insomnia, and certain medications.


Symptoms & Causes

What are some symptoms of depression?

Depression can take various forms. It can be obvious–with symptoms such as sadness, irritability, crying easily, and feeling incapable of joy–or it can be more vague, with features like change in appetite, lack of focus, fatigue, headache, and abdominal pain. Sometimes all of these symptoms occur together, but at other times they happen in isolation. It can take time to identify depression, particularly when there’s not an obvious cause or when the symptoms are strictly physical.

What causes depression? Is it genetic?

Depression is often triggered by a life event. When this happens, it is referred to as situational depression (also called adjustment disorder). If a person experiences a life event that impacts them in a negative way, a period of grief is to be expected. Symptoms of grief are much like symptoms of depression. But if grieving extends beyond a reasonable period of time or if the symptoms are out-of-proportion to what would be expected, that pattern is more consistent with situational depression. 

For example, it’s normal to grieve after a break-up, but if a person can’t leave home and isn’t engaging in day-to-day activities two years after the end of the relationship, then we would consider that person to be situationally depressed.

Sometimes, symptoms of depression occur without any obvious triggering event, and research does seem to suggest that there is a biological component to this sort of depression. There is still much to be learned about the genetic transmission of mental health disorders, but what we do know is that depression appears to have some heritability. In other words, if you have relatives who are depressed, your chances of experiencing depression are higher. 

Of course, just because someone doesn’t seem to have an obvious trigger for depression doesn’t mean that there isn’t an underlying cause (repressed childhood trauma is an example). It’s usually a combination of environment and genetics that contributes to the development of depression, but sometimes one entity plays a more significant role than the other. It’s also important to note that some medical conditions can cause symptoms of depression–hypothyroidism and Parkinson’s disease are two examples.


Types of Depression







Connect with our physicians

Andrew Cunningham, MD and Nora Lansen, MD are both members of the Galileo Clinical Team. Connect with one of our physicians about Depression or any of the many other conditions we treat.

Join Today