Context Social causation (adversity and stress) vs social selection (downward
mobility from familial liability to mental illness) are competing theories
about the origins of mental illness.
Objective To test the role of social selection vs social causation of childhood
psychopathology using a natural experiment.
Design Quasi-experimental, longitudinal study.
Population and Setting A representative population sample of 1420 rural children aged 9 to
13 years at intake were given annual psychiatric assessments for 8 years (1993-2000).
One quarter of the sample were American Indian, and the remaining were predominantly
white. Halfway through the study, a casino opening on the Indian reservation
gave every American Indian an income supplement that increased annually. This
increase moved 14% of study families out of poverty, while 53% remained poor,
and 32% were never poor. Incomes of non-Indian families were unaffected.
Main Outcome Measures Levels of Diagnostic and Statistical Manual of Mental
Disorders, Fourth Edition, psychiatric symptoms in the never-poor,
persistently poor, and ex-poor children were compared for the 4 years before
and after the casino opened.
Results Before the casino opened, the persistently poor and ex-poor children
had more psychiatric symptoms (4.38 and 4.28, respectively) than the never-poor
children (2.75), but after the opening levels among the ex-poor fell to those
of the never-poor children, while levels among those who were persistently
poor remained high (odds ratio, 1.50; 95% confidence interval, 1.08-2.09;
and odds ratio, 0.91; 95% confidence interval, 0.77-1.07, respectively). The
effect was specific to symptoms of conduct and oppositional defiant disorders.
Anxiety and depression symptoms were unaffected. Similar results were found
in non-Indian children whose families moved out of poverty during the same
Conclusions An income intervention that moved families out of poverty for reasons
that cannot be ascribed to family characteristics had a major effect on some
types of children's psychiatric disorders, but not on others. Results support
a social causation explanation for conduct and oppositional disorder, but
not for anxiety or depression.