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.
To test the role of social selection vs social causation of childhood psychopathology
using a natural experiment.
Quasi-experimental, longitudinal study.
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.
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.
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 period.
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.