The study describes the treatment and persistence of mental illness, often manifesting itself in behavioral disorders that can lead to criminal behavior but don't always or even mostly do so. After looking up the abstract -- I'll have to go to another library to get a hard copy of the study -- I see subject headings for:

OUTCOME assessment (Medical care)
INCOME
INDIAN children -- North America
POOR children
CHILD psychiatry
CHILD psychopathology
POVERTY
MENTAL illness

but no CRIME, CRIMINALITY or SOCIOPATHOLOGY.

Just sad children who act out.

Why the immediate jump to crime? Is this only a serious issue if it's a criminal threat? Do we immediately assume that defiant children are automatically vandals, thieves and muggers? Mostly, they make poor life choices that affect themselves badly rather than mount an attack on "society". Things like drug habits (mostly nicotine and alcohol, but others too), dropping out of school, or too-early parenthood.

I need to read the full report of the study before I can comment further, but just so we're plain here: the discussion is about the relationship between illness and economic insecurity, not about predatory behavior among the young.

Regards--
Mary Anne