Despite lots of advancements in the psychology world, many aspects of depression remain mysterious, to mental health professionals and their patients alike. The video below, one of the latest from TEDEd , suggests that this is due to the condition's intangibility — depression isn't a cold or some other illness with physical symptoms that are clear and consistent. However, the video, created by Helen M. Farrell, MD , provides some insight into what depression is, and what signs to look for (in yourself and your loved ones).It's vital to understand the difference between feeling depressed and having depression. Just about all people deal with feelings of sadness, but they pass or are eventually (at times, even easily) resolved. Depression, on the other hand, lasts much longer, following those who suffer from it to the point that they may lose hope of finding a solution. Clinical depression, as explained in this video, can cause sufferers to avoid activities or people that used to excite and engage them, exacerbating the sense of guilt and worthlessness that also accompanies the condition. A lack of energy, appetite, and concentration commonly occurs as well. Most alarmingly, people with depression may deal with recurring thoughts of suicide.With such extreme side effects, one would hope that the 10% of American adults with depression would make solid efforts to seek help. Sadly, though, the video states that "according to the National Institute of Mental Health, it takes the average person suffering with a mental illness over 10 years to ask for help." (Turns out, asking for help is not that easy to do.) This poses a challenge to mental health professionals; after all, they're working hard to explore new options for depression treatment, but when simply finding and choosing the right resources can be so overwhelming, many sufferers won't even get access to innovative treatments that are established.Above all, the video concludes, depression is an illness that calls for treatment, and people shouldn't feel ashamed or afraid of seeking that out. True, depression isn't as visible as other health problems are, but it's just as serious — and the more people view it in this light, the more the stigma around getting help will fade away.Watch the video in full here: