The Hidden Toll of Incarceration: The Longitudinal Association between a History of Incarceration and Inflammation

Background and Purpose: The United States is a world leader in the number of incarcerated people, with nearly two million people in jail or prison. The experience of incarceration is associated with a significant increase in several mental and physical health conditions including diabetes, depression, post-traumatic stress disorder, and cardiovascular disease. Thus, the phenomenon of mass incarceration in the United States poses a major public health concern. The experience of stressful events, such as incarceration, has been found to increase inflammatory signaling in the body. The stress of being incarcerated, among other inflammatory elements of the carceral environment such as social isolation, higher microbial contact, and the consumption of highly processed foods may place incarcerated people at increased risk for inflammatory related diseases (e.g. depression, cardiovascular disease, diabetes). Only one study to date has investigated the effects of incarceration on inflammation, however the study was limited by cross-sectional design and poor use of inflammatory related controls. The present study aimed to understand how incarceration is related to inflammation prospectively with stronger use of controls.

Method: We utilized data from waves I-V of the National Longitudinal Study of Adolescent to Adult Health (Add Health, n=5,845). An OLS regression model examined the association between inflammation and incarceration. C-reactive protein (CRP), an acute phase protein commonly used as an index of inflammation, was utilized as the dependent variable at wave V. Our independent variable was a self-report history of ever being incarcerated between waves IV and V. To control the potential effects of juvenile justice involvement, individuals with a history of incarceration at wave IV were removed from the sample. We included several control variables known to affect CRP, including body mass index (BMI), anti-inflammatory medications, antidepressant medications, tobacco smoking status, recent binge drinking, racial/ethnic identity, gender, and two measures of socioeconomic status. We also included CRP levels at wave IV. Sample weights, pre-calculated by the Add Health team were applied.

Results: The sample had a mean age of 37, identified predominantly as White (79%) and female (69%). The multivariate model testing the association between incarceration and CRP was significant, F(5,832)=143.4, p<0.001. Experiences of incarceration between waves four and five was associated with a 0.241 increase in CRP levels at wave five (p<0.05). This effect was significant even after controlling common covariates, including CRP levels at wave IV (b=0.347, p<0.001).

Conclusion and Implications: The present study was able to identify an increase in inflammation associated with incarceration using a longitudinal design, elucidating the mechanisms by which incarceration impacts health. Findings provide support that current incarceration practices have serious public health implications for a large portion of the U.S. population. Social workers in criminal justice settings may benefit from this work as it highlights the potential for increased inflammatory risk during community reentry. Future research may aim to investigate how interventions currently used to target inflammation could mitigate the deleterious health effects of incarceration.