There's a wealth of information on solitary confinement in the US, including a few excellent articles like this one. This makes me think that the problem is on the way to being solved. A lot still needs to be done, but solitary confinement is now declining.

This site has a huge amount of information, this is probably also the place to look if you want to help: http://solitarywatch.com/

If you want to know more, a good place to start is this national geographic documentary http://documentarystorm.com/solitary-confinement/

and these two excellent articles https://www.byliner.com/susan-greene/stories/the-gray-box-an... http://www.newyorker.com/reporting/2009/03/30/090330fa_fact_...