older adult smokers, poorer performance in smokers was reported for auditory-verbal learning and/or memory [30–34], working memory [26,35,36], executive functions [33,37,38], general intellectual abilities [39], visual search speed [40], processing speed and cognitive flexibility [30–32,38,41,42] and global cognitive function (e.g., brief mental status examinations such as the MMSE) [41]. In a middle-aged cohort of combined current and former smokers, any history of smoking was associated with increased risk for abnormal auditory-verbal memory [43]. Some studies observed the performance of former smokers fell between that of current smokers and NSC in young [25], middle-aged and older adults [31,35,39]. Other studies found no differences between former smokers and NSC [25,30]. The inconsistencies among these studies may be related to the substantial variety of measures used across studies to evaluate the domain of functioning in question as well as inconsistency in the magnitude of neurocognitive dysfunction in the smoking study cohort.
