Introduction

The Food and Drug Administration has the authority to regulate tobacco product constituents, including nicotine, to promote public health. Reducing the nicotine content in cigarettes may lead to lower levels of addiction. Smokers however may compensate by smoking more cigarettes and/or smoking more intensely. The objective of this study was to test whether individual differences in the level of nicotine dependence (as measured by the Fagerstrom Test of Cigarette Dependence [FTCD]) and/or the rate of nicotine metabolism influence smoking behavior and exposure to tobacco toxicants when smokers are switched to reduced nicotine content cigarettes (RNC).

Methods

Data from 51 participants from a previously published clinical trial of RNC were analyzed. Nicotine content of cigarettes was progressively reduced over 6 months and measures of smoking behavior, as well as nicotine metabolites and tobacco smoke toxicant exposure, CYP2A6 and nicotinic CHRNA5-A3-B4 (rs1051730) genotype were measured.

Results

Higher baseline FTCD predicted smoking more cigarettes per day (CPD), higher cotinine and smoke toxicant levels while smoking RNC throughout the study, with no interaction by RNC level. Time to first cigarette (TFC) was associated with differences in compensation. TFC within 10 min was associated with a greater increase in CPD compared to TFC greater than 10 min. Neither rate of nicotine metabolism, nor CYP2A6 or nicotinic receptor genotype, had an effect on the outcome variables of interest.

Conclusions

FTCD is associated with overall exposure to nicotine and other constituents of tobacco smoke, while a short TFC is associated with an increased compensatory response after switching to RNC.

Background

The Environmental Affordances Model (EAM) proposes that the effects of chronic stress on depression are moderated by unhealthy behaviors and race/ethnicity. The unique social structures and contexts of Hispanics/Latinos in the U.S. may influence such relationships. This study evaluated whether unhealthy behaviors weakened the relationship between allostatic load, a measure of chronic stress, and future elevated depressive symptoms among Hispanic Community Health Study/Study of Latinos participants.

Methods

Longitudinal data (2008-2011 and 2014-2017) from 11,623 participants were analyzed. The exposure was allostatic load, an index of twelve established biomarkers categorized using clinically relevant cut points, at Visit 1. Elevated depressive symptoms were operationalized as a score of ≥10 (out of 30) on the CES-D 10 at Visit 2. An index of unhealthy behaviors, with one point each for cigarette smoking, excessive/binge drinking, sedentary behavior, and poor diet quality at Visit 1, was examined as an effect modifier. Multivariable logistic regression, in the overall sample and among Mexicans specifically and adjusted for demographic characteristics and elevated depressive symptoms at Visit 1, was used to model allostatic load, unhealthy behavior index (range: 0-4), and their interaction in relation to elevated depressive symptoms at Visit 2.

Results

Overall, greater allostatic load was associated with higher odds of elevated depressive symptoms after at least 6 years (aOR = 1.06, 95% CI = 1.01, 1.10). Overall, individuals with greater allostatic load and an unhealthy behavior index = 1, compared to those with an unhealthy behavior index = 0, had lower odds of elevated depressive symptoms at follow-up (aβ = -0.065, 95% CI = -0.12, -0.007).

Conclusions

The relationship between chronic stress and depression was partially moderated among Hispanics/Latinos who engaged in unhealthy behavior, which may have reduced their risk of elevated depressive symptoms given more chronic stress.