These results should be evaluated in light of the following limitations. First, this is a relatively homogeneous, middle age, all-male sample. Therefore, associations identified in this study may not be generalized to other populations or for earlier periods of development (Jernigan et al. 2001; Giedd et al. 1999; Sowell et al. 2004; Jernigan and Gamst 2005). However, few studies have been able to assess this relationship at the beginning of middle age and later through aging. A prior study reported current smoking to be a significant predictor of lower total cerebral brain volume in men but not women (Seshadri et al. 2004). Subsequently, these results provide necessary baseline information to understand changes in brain structure specific to smoking-related diseases and aging.
