What is the theological understanding(s) of jinns as the cause of mental illness in Islam?
My question is this:
Islam has historically shown compassion and kindness to the mentally ill (see http://en.wikipedia.org/wiki/History_of_... and also see http://en.wikipedia.org/wiki/Psychology_... in this regard). In medieval times, when the mentally ill were cruelly persecuted in Christian Europe, Muslim physicians posited that mental illness was the product of chemical imbalances etc and not personal fault. Even Mohammed (PBUH) said that three categories of people should be spared judgement, "the child, until he reaches puberty, the sleeping until he wakes, and the insane until he becomes sane."
This notwithstanding, I was watching a documentary on Al Jazeera World News this afternoon about mental illness in Pakistan, and about the immense stigma attached to it. The documentary did not touch on the issue of jinns, but, as can be expected (and as is the case in non-Muslim countries too) highlighted the fact that people were not educated about mental illness etc, which obviously lends way to greater stigma. Upon further research I found that many people believe mental illness is the result (exclusively) of possession by jinns.
What would a more educated, and soundly theological view on this issue be? Can jinns cause mental illness? Does this negate the influence of chemical imbalances etc? How do you know if someone is biologically mentally ill as opposed to possessed by a jinn? What is your view on this issue?
Thanks to all who answer.