Academic Publication

Relationships Between Poverty and Pscyhopathology: A Natural Experiment

E. Jane Costello, Scott N. Compton, Gordon Keeler
JAMA Network
Publication Year:
  • SDG 1 - No Poverty
  • SDG 3 - Good Health and Well-Being
  • SDG 10 - Reduced Inequalities

This psychological study tracked the influx of money provided to a community when a Casino opened nearby. The study found that as families moved out of poverty, children with behavioral disorders became asymptomatic. This study demonstrates the repercussions of poverty and its relationship with mental health and wellness.

Article Abstract: 

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 period.

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.

The association between poverty and mental illness has been described throughout the world and throughout history.1-9 Clinicians and researchers have noted the difficulty of untangling the effects of "social causation, . . . adversity and stress associated with low social statuses" from those of "social selection, [which] posits that genetically predisposed persons drift down to or fail to rise out of" poverty.10

Recent research has emphasized the role played by genetics in an individual's vulnerability to a wide range of psychiatric disorders. Social selection is an example of a theory consistent with gene-environment correlation, in that affected individuals, and often their family members with them, drift down into poverty (and thus into environments that in themselves increase risk for mental illness), while social causation theories reflect a gene-environment interaction in which genetic risk remains latent unless individuals are exposed to the stress of poverty, often by situations beyond their control. The distinction can be important in suggesting different strategies for prevention or treatment.11

Disentangling the effects of social causation and social selection ideally requires an experimental design that manipulates poverty levels and studies the effects on mental illness.11 Income experiments, such as this, have occasionally been done; for example, the New Jersey Negative Income Tax experiment of the 1960s,12,13 and its replications.14-16 However, none of these studies investigated the effects of relief from poverty on mental health. Researchers have had to take advantage of retrospective recall,17 nonexperimental prospective studies,18or at best quasi-experimental situations such as the depression of the 1930s,19 the farm crisis of the 1980s,20-22 or the immigration of European and North African Jews to Israel.10 The extent to which the association between poverty and mental illness reflects social causation or social selection is difficult to test using such natural experiments, because of the difficulty of disentangling movement into or out of poverty from other characteristics that might have caused the change in income. Problems of interpretation are compounded if the quasi-experimental manipulation was unexpected, and if measures before and after change are not available. A truly experimental manipulation of income that showed an improvement in children's behavioral symptoms is the Minnesota Family Investment Program,23 but this study was restricted to single-parent families who were long-term recipients of welfare.

In the middle of an 8-year, community-based study of the development of mental illness in children, we were confronted with a natural experiment in which income levels in an entire community were raised. We used this conjunction of longitudinal evaluation and natural experiment to test the effect of social causation on the trajectory of child and adolescent psychopathology. We examined the mental health of children whose families moved out of poverty, compared with children whose families remained poor despite the intervention and with those who were never poor. If family poverty caused specific emotional and behavioral problems in children,1,4,24 then after poverty was removed these psychiatric symptoms should improve or disappear.


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