Smoking and the developing brain: Altered white matter microstructure in attention‐deficit/hyperactivity disorder and healthy controls

Abstract

Brain white matter (WM) tracts, playing a vital role in the communication between brain regions, undergo important maturational changes during adolescence and young adulthood, a critical period for the development of nicotine dependence. Attention-deficit/hyperactivity disorder (ADHD) is associated with increased smoking and widespread WM abnormalities, suggesting that the developing ADHD brain might be especially vulnerable to effects of smoking. This study aims to investigate the effect of smoking on (WM) microstructure in adolescents and young adults with and without ADHD. Diffusion tensor imaging was performed in an extensively phenotyped sample of nonsmokers (n = 95, 50.5% ADHD), irregular smokers (n = 41, 58.5% ADHD), and regular smokers (n = 50, 82.5% ADHD), aged 14-24 years. A whole-brain voxelwise approach investigated associations of smoking, ADHD and their interaction, with WM microstructure as measured by fractional anisotropy (FA) and mean diffusivity (MD). Widespread alterations in FA and MD were found for regular smokers compared to irregular and nonsmokers, mainly located in the corpus callosum and WM tracts surrounding the basal ganglia. Several regions overlapped with regions of altered FA for ADHD versus controls, albeit in different directions. Irregular and nonsmokers did not differ, and ADHD and smoking did not interact. Results implicate that smoking and ADHD have independent effects on WM microstructure, and possibly do not share underlying mechanisms. Two mechanisms may play a role in the current results. First, smoking may cause alterations in WM microstructure in the maturing brain. Second, pre-existing WM microstructure differences possibly reflect a risk factor for development of a smoking addiction.

White matter development and tobacco smoking in young adults: A systematic review with recommendations for future research

“…All identified studies reported increases in FA among adolescent/young adult smokers in comparison to control participants, and these were most frequently reported in regions of the corpus callosum (genu, body and splenium), internal capsules and superior longitudinal fasciculus (Jacobsen et al, 2007; Liao et al, 2011; van Ewijk et al, 2015; Yu et al, 2015). Taken together, these data suggest that tobacco smoking among adolescents and young adults is associated with increases in white-matter fiber coherence or ‘integrity’, insofar as these may be inferred from FA values.…”

Thinner Medial Temporal Cortex in Adolescents With Attention-Deficit/Hyperactivity Disorder and the Effects of Stimulants

“…The current study adds to the previous volumetric findings of our group with ADHD being associated with global rather than local volume reductions 6 . Other neuroimaging studies based on the same sample investigated volumetric features, 24-26 structural connectivity, [27][28][29] or functional MRI. [30][31][32][33] To the best of our knowledge, CT has not previously been studied in an ADHD sample of this size.…”

Circuitry of self-control and its role in reducing addiction

“…Support for this network comes from many fMRI studies of activation of these areas during tasks involving the resolution of conflict [9] and control of thoughts and feelings [10]. A recent developmental study highlighted reduced white matter in these same networks in vulnerability to smoking addiction [11].…”

“…Support for this network comes from many fMRI studies of activation of these areas during tasks involving the resolution of conflict [9] and control of thoughts and feelings [10]. A recent developmental study highlighted reduced white matter in these same networks in vulnerability to smoking addiction [11].The relation of control networks to the instantiation of goals is supported by the finding that lesions of the frontal lobes are associated with a tendency to neglect goals during task performance [12]. Goals often involve a complex hierarchy of subgoals, which must be implemented in a Opinion Glossary Cortisol: a steroid hormone, more specifically a glucocorticoid, is produced by the adrenal cortex.…”