Functional brain connectomes reflect acute and chronic cannabis use
Johannes G. Ramaekers, Natasha L. Mason, Stefan W. Toennes, Eef L. Theunissen, Enrico Amico
Scientific Reports February 14, 2022 DOI: 10.1038/s41598-022-06509-9 via OpenAlex
Summary
Acute cannabis intoxication and chronic cannabis use produce distinct patterns of altered connectivity across the whole brain, not just in isolated regions. Using ultra-high field (7T) resting state fMRI scans of 26 cannabis users under placebo and after vaporizing cannabis, two data-driven methods revealed that chronic users showed broad hyperconnectivity across major brain networks compared to occasional users, suggesting adaptive network reorganization from prolonged exposure. A separate spatial pattern—hypoconnectivity in dorsal attention, limbic, subcortical, and cerebellum networks combined with hyperconnectivity between the default mode and ventral attention network—was linked to the subjective feeling of being high during acute intoxication. These whole-brain approaches distinguish short- from long-term cannabis effects and may help probe the transition from occasional to chronic use.
Study at a glance
| Characteristics | Within-subjects, placebo-controlled, crossover study Peer reviewed |
|---|---|
| Sample size | 26 |
| Population | Cannabis users (chronic and occasional) |
| Topics | Cannabis Default mode network |
| Keywords | Neuroscience Resting State FMRI Delta-9-tetrahydrocannabinol Nerve net |
| Citations | 26 |
| Key finding | Chronic cannabis users exhibited broad hyperconnectivity across major brain networks compared to occasional users, while acute intoxication produced a distinct pattern of hypoconnectivity in some networks and hyperconnectivity between default mode and ventral attention networks linked to subjective high. |
Abstract
Resting state fMRI has been employed to identify alterations in functional connectivity within or between brain regions following acute and chronic exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive component in cannabis. Most studies focused a priori on a limited number of local brain areas or circuits, without considering the impact of cannabis on whole-brain network organization. The present study attempted to identify changes in the whole-brain human functional connectome as assessed with ultra-high field (7T) resting state scans of cannabis users (N = 26) during placebo and following vaporization of cannabis. Two distinct data-driven methodologies, i.e. network-based statistics (NBS) and connICA, were used to identify changes in functional connectomes associated with acute cannabis intoxication and history of cannabis use. Both methodologies revealed a broad state of hyperconnectivity within the entire range of major brain networks in chronic cannabis users compared to occasional cannabis users, which might be reflective of an adaptive network reorganization following prolonged cannabis exposure. The connICA methodology also extracted a distinct spatial connectivity pattern of hypoconnectivity involving the dorsal attention, limbic, subcortical and cerebellum networks and of hyperconnectivity between the default mode and ventral attention network, that was associated with the feeling of subjective high during THC intoxication. Whole-brain network approaches identified spatial patterns in functional brain connectomes that distinguished acute from chronic cannabis use, and offer an important utility for probing the interplay between short and long-term alterations in functional brain dynamics when progressing from occasional to chronic use of cannabis.