Stress of incarceration: Unexpected findings from the CARDIA study

Background: Individuals with a history of incarceration have greater morbidity and mortality from chronic diseases compared to the general population. Increased stress or dysregulated stress response are a plausible mechanisms for these differences, though no study has directly explored the association of incarceration with stress responses. Methods: We examined the association between history of incarceration and responses to stress using the Coronary Artery Risk Development In Young Adults (CARDIA) study-a cohort of young adults aged 18-30 years at enrollment in 1985-86 (year 0), balanced by sex, race (black and white), and education (high school education versus less). We have previously reported higher incidence of hypertension for previously incarcerated CARDIA participants. Here we examined the association of incarceration history with (1) vascular reactivity in response to stressful activities-- star-tracing task and videogame; (2) allostatic load, a cumulative measure of body ”wear and tear” that combines cardiometabolic, inflammatory, pulmonary, and renal dysfunction markers, and (3) stress endocrine response (cortisol, norepinephrine and epinephrine levels). Results: Of 5113 participants, 351 (7%) reported previous incarceration at years 0 or 2. At year 2, individuals with a history of incarceration had less vascular reactivity in response to a star tracing (D systolic blood pressure (SBP) 8.3±6.9 mmHg vs. 9.7±7.9 mmHg, p=0.003) and videogame tasks (D SBP 8.3±7.9 vs. 9.7±6.9, p=0.003), even after adjustment for SBP and sociodemographics. Former inmates had lower mean allostatic loads at year 15-20 compared to those without prior incarceration (1.7 ± 1.7 vs. 2.0 ± 1.7, p=0.04), with lower plasma levels of inflammatory markers but higher levels of cardiometabolic factors. We detected no differences in year 15 cortisol, norepinephrine, and epinephrine levels between those with and without a history of incarceration. Adjustment with demographics, income, education, and drug use only strengthened the observed association. Inverse probability weighting to account for lower follow-up rates among former inmates did not change these findings. Conclusion: Individuals with a history of incarceration have lower cardiovascular response to stress, lower allostatic loads, and similar endocrine response to stress compared to those without this history. Increased stress or excessive allostatic load may not explain increased rates of disease in this population.