I've been doing some research this afternoon and come up with some interesting info. Well I think it's interesting because I've not read it before but if these links have been posted before please forgive me.
Here's an interesting abstract:
The mental health of Jehovah's Witnesses
J Spencer
The function of religion in human society is complex. The part played by religion in psychiatric disorders is even more obscure. Previous literature and theories are divided into two groups: one school believes that intense religiosity is a symptom-complex indicative of psychiatric disorder, while the opposing view is that religious belief in some way acts as a defence mechanism protecting the individual and his psyche. The present study of 50 Jehovah's Witnesses admitted to the Mental Health Service facilities of Western Australia suggests that members of this section of the community are more likely to be admitted to a psychiatric hospital than the general population. Furthermore, followers of the sect are three times more likely to be diagnosed as suffering from schizophrenia and nearly four times more likely from paranoid schizophrenia than the rest of the population at risk. These findings suggest that being a member of the Jehovah's Witnesses faith may be a risk factor predisposing to a schizophrenic illness. Further studies would be interesting in investigating whether pre-psychotic people are more likely to join the sect than normal people and what part (if any) membership has in bringing about such a breakdown.
More: http://bjp.rcpsych.org/cgi/content/abstract/126/6/556
Summary
It is a common observation among mental health personnel, supported by all published studies, that the mental illness rate among JW's far surpasses that of the population as a whole. Many factors are found to contribute to this - JW's tend to recruit individuals with emotional problems; there is a great deal of pressure to conform within the congregation, and there is a belief structure which clearly causes emotional turmoil. The fact that JW's are recruited from the lower socio-economic statuses of society and tend to seriously alienate and often force out of the movement the more intelligent and better educated members is also highly instruments in contribution to the mental illness rate. Once a JW develops emotional problems he is actively encouraged to avoid accepting "worldly advice" either from secular books or secular mental health personnel. The psychiatric profession as a whole is severely criticized, and Witnesses are encouraged to consult only their Elders, most of whom are poorly equipped to deal with most normal interpersonal relation frictions let alone what be termed neurotic and psychotic maladjustment. In dealing with members, Elders tend to offer poor advice and rely on punitive criticism or threats ("If you do not….you will not survive Armageddon…") to change behavior. This approach typically elicits increased guilt and/or a high level of aggression in the Witnesses. This factor is probably influential in the high rate of aggression crimes found among Witnesses.
More: http://www.rickross.com/reference/jw/jw73.html
Cultic Studies Journal Psychological Manipulation and Society Vol. 14, No. 1, 1997
Wifely Subjection: Mental Health Issues in Jehovah’s Witness Women
From: http://www.csj.org/pub_csj/csj_vol14_no1_97/abs_wifely.htm
I'll add more if I find them.