Cannabis, cigarettes, and their co-occurring use: disentangling differences in default mode network functional connectivity
Reagan R Wetherill, Zhuo Fang, Kanchana Jagannathan, A. Childress, H. Rao, Teresa R Franklin
Drug and Alcohol Dependence June 10, 2015 DOI: 10.1016/j.drugalcdep.2015.05.046 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Cross-sectional observational study Peer reviewed |
|---|---|
| Sample size | 87 |
| Population | Adults aged 20–57 with cannabis dependence, nicotine dependence, or neither |
| Topics | Cannabis Default mode network |
| Key findings | All substance-using groups showed lower default-mode network connectivity than healthy controls, with unique connectivity differences between the posterior cingulate cortex and specific brain regions across groups. |
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.
Comparable studies
Other cross-sectional and survey studies on default mode network, most cited first.
Citations in the library
Cited by 18
- Cannabis-induced altered states of consciousness are associated with specific dynamic brain connectivity states Journal of Psychopharmacology June 3, 2019
- Treating Addiction: Perspectives from EEG and Imaging Studies on Psychedelics. International review of neurobiology 2016
- Associations between regular cannabis use and brain resting-state functional connectivity in adolescents and adults Journal of Psychopharmacology July 29, 2023
- Psychedelics and substance use disorder treatment. International review of neurobiology 2025
- How adolescent cannabis use reshapes the developing brain — a systematic review Frontiers in Psychiatry April 27, 2026
and 13 more in the library
Cites 10
- A default mode of brain function Proceedings of the National Academy of Sciences January 16, 2001
- The default mode network and social understanding of others: what do brain connectivity studies tell us Frontiers in Human Neuroscience 2014
- Evidence for involvement of the insula in the psychotropic effects of THC in humans: a double-blind, randomized pharmacological MRI study The International Journal of Neuropsychopharmacology April 14, 2011
- Cannabis, Cigarettes, and Their Co-Occurring Use: Disentangling Differences in Gray Matter Volume. The International Journal of Neuropsychopharmacology June 4, 2015
- Functional connectivity alterations in brain networks relevant to self-awareness in chronic cannabis users. Journal of Psychiatric Research April 2014
and 5 more in the library