Well, you are right that depression is not an attitude. It's a disease, a malfunction. But like any other disease, it can happen from or be aggravated by extern

Well, you are right that depression is not an attitude. It's a disease, a malfunction. But like any other disease, it can happen from or be aggravated by external factors. If you are, to some degree, predisposed to depression, you are more likely to aggravate or trigger it by living in an hostile environment than if you are living your dream life. It's like being predisposed to cardiovascular diseases : even if you are predisposed, you are more likely to not have any issue if you never encounter stress, eat healthy and have an active life. Saying depression can be contagious by no means implies that depression is an attitude and not a disease.