“…), cigarette smoke (CS) contains considerably higher levels of several behaviorally active non-nicotine constituents including monoamine oxidase (MAO) inhibitors (e.g., the β-carbolines harmane and norharmane, also called harman and norharman), minor tobacco alkaloids (e.g., nornicotine, anabasine), and volatile organic compounds (VOCs) (e.g., acetaldehyde, toluene) (e.g., Margham et al, 2016 ; National Academies of Sciences, Engineering, and Medicine, 2018 ; Belushkin et al, 2020 ). These compounds can mimic or enhance nicotine’s addiction-related effects in preclinical models, or may have abuse liability themselves (for review, see Hoffman and Evans, 2013 ; LeSage et al, 2018 ). The greater abuse liability of cigarettes versus ANDs may therefore reflect the higher levels of MAO inhibitors and other behaviorally active non-nicotine constituents in CS.…”