And worse yet, the cause is wildly misunderstood. One person's debilitating depressing might be resolved spectacularly via light therapy, another via a single medication, another yet only moderated by a constellation of medications, and others who have undergone a variety of treatments for a decade with little improvement.

Compare that to, say, a broken leg, which is much easier to understand.

There's a huge stigma attached to certain cancers, too, like lung cancer not caused by smoking.