Not all cases of depression are due to "chemical imbalances" are they? Some depression can be environmantal, in other words a result of situations and circumstances you are contending with on a day-to-day basis.
In either case, what causes or brings on the depression is not as clear as the effect of the depression.
My wife, after the birth of our second child, began experiencing more intense depression. For years we had viewed each other as being one of us pessimistic (her) and the other optimistic (me) and that this was why we dealt with situations differently. We even considered it Jehovah's "blessing" that we were this way and were together so we could balance each other. Looking back on this now makes me embarrassed that I ever thought this way. In any case my approach to my wife was as follows (and IMO identifies a root problem in the common approach to depression by many)
I would note that my wife was apathetic, unproductive, irritable, and lacked motivation. So I would be "sensitive" and ask her "What's wrong?"
My wife would reply, "I don't know." I would then, in my infinite wisdom, begin a long, drawn out conversation breaking down everything that's been going on and agonizingly drag her thru each event over the last several days thinking at some point I would be able to isolate a specific thing and be able to proclaim "Aha! that's what it is" bada-bing bada-boom, your fixed!
Of course this didn't work, it only served to create more tension and add to the already gloomy situation.
The problem really is that a person, when depressed (whether clinical or environmental) cannot think straight. They don't have the ability to pause, rewind, isolate, and solve. To ask them to do so is ridiculous. They lack energy, drive, stamina, motivation, and joy. They simply cannot bring themselves to do things like read the Bible, go to meetings, pray, exercise, etc. They may have moments where they feel better and are able to do some of these things, but by and large, they simply can't sustain it. They need help to be able to regain perspective, focus, and in many cases this help can only come in the form of presribed drugs/meds, combined with QUALIFIED assistance from a TRAINED PROFESSIONAL.
A person that hasn't experienced depression beyond momentary "down" feelings of disappointment, cannot comprehend what a depressed person is going through. It's not momentary for them. It's not disappointment for them. It is real and it is debillitating mentally and physically. I learned this through experience and effort to never forget it. No amaount of mental effort on the part of the depressed person can "solve" it. They may never "solve" it. Thhey may learn to live with it, but usually it is only because of getting the proper assistance from "QUALIFIED" resources.
Something that helped me to understand it better was thinking of the "depressing" of a brake pedal. To depress the brakes, one applies pressure to the pedal and forces it down and maintains the pressure until coming to a stop. The pedal is "depressed". The pedal has no say over it, it only receives the pressure and goes down and stays down. A depressed person is pressed down by pressure from an outside source (whether environmental or chemical) beyond their control and they have little to no say over the source of pressure of the effect. They simply must cave under it and must wit for the pressure to subside (due to qualified assistance).
I truly feel the WTS and their cronies try to equate disappointment to depression and that is a fundamental flaw in their approach and their presribed solution. Reading the Bible, praying, meeting attendance may very well help a JW experiencing disappointment, but it has little to do with assisting a depressed soul.