ASAP Science has a new explainer on depression.
Noting that the true causes of depression have yet to be pinned down precisely, the video explains the biological basis for depression and how the growth and connections of brain cells play a large roll.
It also considers the hereditary nature of depression and bipolar disorder - studies have shown that if one identical twin has bipolar disorder the other twin has a 60 to 80 percent chance of developing it too.
The video concludes with an introduction to depression in other species.
Watch, AFTER THE JUMP...
You can also read David Mixner's recent piece on his struggles with depression here.