Back in the 70s & 80s my father was a big mover and shaker withing the realm of the Watchtower. He had been recruited by the Watchtower to make a documentary on District Conventions back in the 80s. A previous project he started on his own was looking into mental illness among Jehovah's Witnesses.
My fathers findings were that there was a higher percentage of mentally ill among JWs than other Christian sects and that JWs seemed to attract the mentally ill into their ranks. He was told to bury his research.
I personally saw many mentally ill recruiting into the Witnesses. In fact, most coming in who are not born-ins tended to live in poverty, be mentally ill, or both. What was sad was how many of these who suffer from mental illness were told to stop taking their meds and seeing doctors. They were told that there mental illness was actually demons and that they needed to rely on Jehovah, not medicine, for help.