Yes and yes.
First, people with mental health issues (and I prefer that term to "mentally ill," though I can't explain why) are more likely to be attracted to an organization that says (a) their problems are the fault of the Devil and an evil system of things, and (b) that a magic imaginary friend in the sky is going to fix those problems--someday, real soon, any time now.
This attaction is even more deep for those who have struggled for years with depression and other mental health problems, because they're being offered a fool-proof solution that they only have to wait for, rather than one that requires a lot of personal effort (as well as some medications that can have nasty side-effects and are expensive) with no promise of full recovery.
Second, those people then raise their children in "da Troof." The kids, whether they are genetically pre-disposed to depression, mood disorders or other mental/emotional difficulties or not, internalize all the negative ways of thinking about themselves and the world that set up a powerless, hopeless world view. Note that I said hopeless; that's because the "hope" that JWs offer is always delayed--there's no immediate payoff or relief, just endless work for no improved mental/emotional state in the here and now.
That kind of mental conditioning (and I've heard JWs refer to what they do as "mental regulating") has the consequence, unintended or not, of altering brain chemistry. I think, from observation and from what I've learned about mood disorders, that JWs actually induce depression and low self-esteem in their children through their child-rearing methods. Their "rod" is useful only for getting the meds down from the shelf.
Kids raised as JWs suffer more than most kids raised by American standards (and there's a lot of suffering for kids in general in this country): the childrens' own observations and feelings are discounted or denied, which causes them to not trust themselves; punishment is arbitrary and "for their own good" (and we all know about the unrealistic expectations of children the JWs have and the brutal way those expectations are enforced); the threat of destruction hangs over their little heads in the most graphic way possible, and they're discouraged from forming close emotional attachments or developing personal interests and strengths (heck, even pets were discouraged as taking time away from Jehovah in my congregation); and finally, no amount of work is enough--always, more is asked. What better way to develop anxiety, low self-esteem, attachment disorder, alcohol/drug abuse and depression? Get 'em while they're young, and they'll spend a fortune on therapy.
The good news (and I mean "good" in the sense of "good," not in the JW sense of "keep doing more and getting less") is that treatment of mental and emotional problems has advanced so much in the past few years that many who seek it get relief far beyond what they would find even a decade ago. For all their problems, anti-depressants do offer some a platform from which to do the serious behavioral and emotional work required to combat depression, and some of the newer approaches to post-traumatic stress disorder (PTSD, which as far as I can tell, everyone raised a JW has to some degree or other) are incredibly effective (I'm thinking here of EMDR and some of the new drug therapies).
There is hope. Just not the "imaginary friend is gonna make me better" kind.
Jankyn (sober 21 years and hasn't been suicidal in 20 years)