Cannabis, cigarettes, and their co-occurring use: Disentangling differences in default mode network functional...

Area of Science:

• Neuroimaging
• Neuroscience
• Addiction Research

Background:

• Resting-state functional connectivity (rsFC) assesses neural network function noninvasively.
• Altered default mode network (DMN) connectivity is linked to nicotine and cannabis use.
• Limited research exists on the impact of co-occurring cannabis and tobacco use on DMN connectivity.

Purpose of the Study:

• To investigate DMN functional connectivity differences in individuals with co-occurring cannabis and tobacco use.
• To compare DMN connectivity in four groups: cannabis-dependent (no tobacco), co-occurring users, nicotine-dependent (no cannabis), and healthy controls.
• To explore associations between DMN connectivity strength and substance use duration/intensity.

Main Methods:

• Posterior cingulate cortex (PCC) seed-based rsFC analyses were employed.
• Four participant groups were analyzed: cannabis-dependent (n=19), co-occurring users (n=23), nicotine-dependent (n=24), and controls (n=21).
• Analyses controlled for age, sex, and alcohol use; associations with use measures were explored.

Main Results:

• PCC seed-based analysis identified core DMN nodes.
• Cannabis-dependent, nicotine-dependent, and co-occurring use groups exhibited reduced DMN connectivity compared to controls.
• Specific group differences were observed in PCC connectivity with the cerebellum, medial prefrontal cortex, parahippocampus, and anterior insula; cannabis use duration correlated with PCC-right anterior insula connectivity.

Conclusions:

• This study provides evidence of altered DMN connectivity associated with cannabis and tobacco exposure.
• Co-occurring cannabis and tobacco use is linked to distinct patterns of DMN functional connectivity.
• Findings contribute to understanding the neurobiological effects of combined substance use.