Across all measures, smaller brain structures were associated with increasing cigarette pack-years. However, the magnitudes of these correlations were moderate to small in magnitude. Similar results have been reported in prior studies using community-based samples (Chen et al. 2006; Das et al. 2012). Structural alterations are considered to be important for processing information in dynamic networks according to environmental demands. The occurrence of dynamic structural alterations has been demonstrated to mirror functional processing in order to address external demands placed on the brain and to do so relatively efficiently and consistently (May et al. 2007). Despite the neurotoxic properties of smoking (Ferrea and Winterer 2009), chronic exposure to nicotine induces neuroadaptation (Menossi et al. 2013) rather than severe dysfunction. Therefore, a measure of lifetime cigarette use, such as that captured in pack-years may be expected to have small phenotypic correlations with brain morphometry.
