Relationships Between Iron Status, Cognitive Performance, and Smoking Cessation
Abstract Objectives Smoking cessation research suggests that women are more likely than men to respond to financial incentives to quit smoking, despite having lower rates of smoking cessation overall. Animal models suggest that iron deficiency, which is more prevalent in women, may alter dopaminergic pathways involved in both reward processing and addiction. The present study examines the extent to which iron status impacts ability to quit smoking and performance on a battery of cognitive tasks, including tasks assessing learning and decision-making which depend on the integrity of the dopaminergic pathways. Methods Participants were recruited from a local smoking cessation clinic and followed for 6 months as they received counseling to quit smoking. Visits included a baseline appointment, as well as 1- and 6-month follow up visits. At each appointment, participants performed cognitive tests, including the serial reaction time task (SRT) and probabilistic selection task (PST), with concurrent EEG, then gave a small sample of blood. Smoking behavior was examined using time to relapse (TTR), which was the week (1–26) in which the participant relapsed, if relapse occurred. Iron status variables of interest were hemoglobin (Hb) and percentile of the NHANES III age- and race-adjusted distributions of serum ferritin (sFtP). Correlations examined the associations between iron status variables and reaction times (RTs) on the SRT and PST, choice behavior on PST, and TTR. Results TTR was positively related to sFtP (r = 0.79, P < .005). Regarding the cognitive measures, there was a nonlinear relationship between sFtP and RT for the SRT task: participants with sFtP at or below the 45th percentile had a negative relationship with RT, while those with sFtP above the 55th percentile had a positive one. Hb was negatively correlated with learning from negative consequences in the PST. In addition, RTs for high-conflict choices and correct responses had a nonlinear relationship with sFtP like that found with the SRT. Conclusions Variations in iron affect smoking cessation as well as cognitive performance. Being low in iron may represent an additional burden to a woman who attempts to quit smoking. Funding Sources TSET Health Promotion Research Center - Oklahoma Tobacco Settlement Endowment Trust (TSET; Grant # r21–02) and NCI Support Grant P30CA225520.