What is the cause of the spread of psychological diseases in the developed world?

Possibilities: Some point to the breakdown of nuclear & extended families in the developed world, as compared to more underdeveloped nations. Early native americans had psychotic people -- and extended family + tribe took care of them. Healthy development requires consistent parenting, which often fails here. Toxic environmental issues, & turning to substance abuse might bring more illness in developed world too.

Developed world: Having experience overseas, my guess is that in underdeveloped countries when a person shows symptoms of mental illness, he/she are taken by family to isolation or they are labeled insane & end up roaming the streets. Anything less is treated thru nature/nurture, with proper medical/psychological interventions being reserved for the rich or fortunate few.