as “young adults”, 40–59 as “middle-aged adults” and 60–90 years of age as “older adults”. In studies where the participants do not conform to the above defined age groups, specific age ranges are provided. For reviews on the effects of chronic smoking on brain neurobiology and function in alcohol and substance use disorders see [13–15]. Please refer to [16–20] for thorough reviews on the acute effects of nicotine administration and nicotine withdrawal on brain neurobiology and neurocognition (although not the focus of this review, these topics are briefly addressed in Section 4). For inclusive reviews on functional MRI and nuclear imaging findings in chronic smokers see [21,22].
