A Systematic Review of the Association between Toxic Stress and Poverty

Background and Purpose

Poverty is a major national issue, with 40.6 million people living in poverty in the United States and 18% of children living below the poverty line. Research is clear that living in poverty leads to detrimental health and well-being outcomes for individuals and families. Recently, toxic stress has been identified as a key mechanism by which poverty impacts health. Toxic stress is the detrimental biological response to living with prolonged and unmediated stress that can occur when someone lives in persistent poverty or in a high poverty neighborhood with limited resources and increased exposure to negative environmental conditions. This manuscript provides a systematic review of the literature to assess the relationship between toxic stress and poverty. Poverty is defined using three constructs: 1) income poverty; 2) socioeconomic status; and 3) neighborhood poverty.

Methods

In developing and conducting this systematic review, we adopted the guidelines outlined in the PRISMA statement. A total of 56 articles met the inclusion criteria from our search and were retained for analysis. Subsequent to the full-text review, relevant data from the 56 articles were extracted into an analysis framework. Three poverty constructs are included in the study. The first is a measure of income poverty operationalized as annual income. Second, is a measure of SES and includes the Hollingshead Four Factor Index of Social Status. The third poverty construct captures neighborhood poverty. The reviewed articles explored the effects of the above poverty constructs on both individual measures of physical stress outcomes as well as measures cumulative biological stress.

Results

Twenty-four (72.7%) of the 33 studies examining the relationships between an individual biomarker and poverty construct were either positive or mixed. Fifteen (45.5%) used a measure of income poverty as a predictor. Eleven (73.3%) were either positive or mixed. A measure of SES was used as a predictor in eleven (33.3%) of the 33 studies. Six (54.5%) of the 11 were either positive or mixed. Seven (21.2%) of the 33 used a measure of neighborhood poverty to predict an individual biomarker outcome. All (100%) of the relationships were either positive or mixed.

Of the 30 analyzed studies between a cumulative biomarker and poverty construct, 29 (96.7%) were positive or mixed. Income poverty was the predictor in nine (30.0%) of the 30 relationships. All (100%) were either positive or mixed. Ten (33.3%) of the studies used SES. Of these, nine (90.0%) were positive or mixed. Neighborhood poverty was the predictor in 11 (36.7%) of the studies. All (100%) were positive or mixed.

Conclusions

To our knowledge, this is the first systematic review to describe the relationship between poverty and physical stress outcomes. Findings demonstrate substantial evidence of the relationship between poverty and toxic stress with the strongest evidence showing a relationship between neighborhood poverty and toxic stress. Social work practitioners need to be aware of the biological response individuals face when they experience all types of poverty and interventions must be developed to address the physical responses produced from living in poverty.