The level and chronicity of smoking, as reflected in the number of cigarettes smoked per day, duration of smoking over lifetime, and/or dose-duration (i.e., pack-years) were inversely related to various domains of neurocognition in adults across a wide age range [25,30,32,45,52,55,56]. Several reports indicate chronic smoking is associated with increased risk for various forms of dementia, in particular Alzheimer’s Disease and vascular dementia [57–61]. This risk may be modulated through the apolipoprotein E ɛ4 (ApoE4) genotype, a known genetic risk for the development of Alzheimer’s Disease [52,54]. Interestingly, some studies have reported that risk for development of Alzheimer’s Disease was greater in smokers who were not ApoE4 carriers [52,54,58,59].
