Does Income Affect Health? Evidence from a Randomized Controlled Trial of a Guaranteed Income

This paper provides new evidence on the causal relationship between income and health by studying a randomized experiment in which 1,000 low-income adults in the United States received $1,000 per month for three years, with 2,000 control participants receiving $50 over that same period. The cash transfer resulted in large but short-lived improvements in stress and food security, greater use of hospital and emergency department care, and increased medical spending of about $20 per month in the treatment relative to the control group. Our results also suggest that the use of other office-based care—particularly dental care—may have increased as a result of the transfer. However, we find no effect of the transfer across several measures of physical health as captured by multiple well-validated survey measures and biomarkers derived from blood draws. We can rule out even very small improvements in physical health and the effect that would be implied by the cross-sectional correlation between income and health lies well outside our confidence intervals. We also find that the transfer did not improve mental health after the first year and by year 2 we can again reject very small improvements. We also find precise null effects on self-reported access to health care, physical activity, sleep, and several other measures related to preventive care and health behaviors. Our results imply that more targeted interventions may be more effective at reducing health inequality between high- and low-income individuals, at least for the population and time frame that we study.