Cannabis, cigarettes, and their co-occurring use: Disentangling differences in default mode network functional connectivity. (1st August 2015)

• Record Type: Journal Article
• Authors: Wetherill, Reagan R.; Fang, Zhuo; Jagannathan, Kanchana; Childress, Anna Rose; Rao, Hengyi; Franklin, Teresa R.
• Is Part Of: Drug and alcohol dependence. Volume 153(2015)
• Page Start: 116
• Page End: 123
• Publication Date: 2015-08-01
• Subjects: Cannabis -- Dependence -- Resting state functional connectivity -- Nicotine; Drug abuse -- Periodicals; Alcoholism -- Periodicals; 616.86
• DOI: 10.1016/j.drugalcdep.2015.05.046
• Languages: English
• ISSNs: 0376-8716

Abstract

Highlights: We examine resting state functional connectivity of the default mode network. We compare connectivity strength differences. All of the smoking groups show lower connectivity strengths than controls. Default mode network-insula connectivity strength correlates with cannabis use. Abstract: Background: Resting-state functional connectivity is a noninvasive, neuroimaging method for assessing neural network function. Altered functional connectivity among regions of the default-mode network have been associated with both nicotine and cannabis use; however, less is known about co-occurring cannabis and tobacco use. Methods: We used posterior cingulate cortex (PCC) seed-based resting-state functional connectivity analyses to examine default mode network (DMN) connectivity strength differences between four groups: (1) individuals diagnosed with cannabis dependence who do not smoke tobacco ( n = 19; ages 20–50), (2) cannabis-dependent individuals who smoke tobacco ( n = 23, ages 21–52), (3) cannabis-naïve, nicotine-dependent individuals who smoke tobacco ( n = 24, ages 21–57), and (4) cannabis- and tobacco-naïve healthy controls ( n = 21, ages 21–50), controlling for age, sex, and alcohol use. We also explored associations between connectivity strength and measures of cannabis and tobacco use. Results: PCC seed-based analyses identified the core nodes of the DMN (i.e., PCC, medial prefrontal cortex, inferior parietal cortex, and temporal cortex). In general, the cannabis-dependent, nicotine-dependent, and co-occurring use groups showed lower DMN connectivity strengths than controls, with unique group differences in connectivity strength between the PCC and the cerebellum, medial prefrontal cortex, parahippocampus, and anterior insula. In cannabis-dependent individuals, PCC–right anterior insula connectivity strength correlated with duration of cannabis use. Conclusions: This study extends previous research that independently examined the differences in resting-state functional connectivity among individuals who smoke cannabis and tobacco by including an examination of co-occurring cannabis and tobacco use and provides further evidence that cannabis and tobacco exposure is associated with alterations in DMN connectivity.