A single dose of THC disrupted brain network connectivity in young adult cannabis users | Research

The takeaway

In a double-blind study of 33 occasional cannabis users, a single moderate THC dose reduced functional connectivity within corticostriatal and sensory brain networks during rest.

Neuroscience researchers, addiction medicine specialists, cannabis pharmacology researchers

Widespread connectivity reductions unrelated to subjective effects

What the researchers found

THC (7.5 mg oral) reduced within-network intrinsic connectivity in corticostriatal circuits and networks associated with sensory systems, interoceptive experiences, and spatial reasoning compared to placebo. THC also reduced between-network connectivity involving anterior cingulate cortex, dorsal insula, ventral insula, and lingual gyrus regions. Network connectivity changes during THC were not related to subjective drug effects or recent cannabis use frequency.

Why it matters

This is one of few studies examining whole-brain network effects of THC rather than focusing on individual brain regions. The widespread connectivity reductions across sensory, cognitive, and reward circuits help explain the diverse behavioral and perceptual changes people experience while intoxicated.

The numbers in context

n=33 occasional cannabis users; THC 7.5 mg oral; reduced corticostriatal connectivity; reduced sensory network connectivity; reduced between-network connectivity (ACC-dorsal insula and ventral insula-lingual gyrus); no relationship to subjective effects or use frequency

How the study worked

Within-subject, double-blind, randomized study. 33 healthy occasional cannabis users received THC (7.5 mg oral) and placebo before completing resting-state fMRI during peak intoxication. Group-information-guided independent component analysis identified whole-brain networks. Within-sample t-tests assessed connectivity differences.

What this study cannot tell us

Modest sample (n=33). Only occasional cannabis users studied; heavy users might show different patterns. Single dose examined; chronic effects unknown. Resting-state fMRI captures only spontaneous brain activity, not task-related function.

How to read the evidence

Double-blind within-subject RCT with whole-brain analysis provides moderate evidence of acute THC effects, limited by modest sample size and focus on occasional users only.

When this study was published

2025 publication

The bigger picture

Understanding how THC disrupts brain networks in casual users provides baseline data for studying whether these acute disruptions become chronic with regular use. The finding that subjective experience did not predict brain changes suggests people may not perceive the extent of neural disruption THC causes.

Questions still open

Do these network connectivity reductions persist beyond acute intoxication? Would chronic cannabis users show blunted or enhanced network effects?

Common questions

What does reduced brain connectivity mean?

Reduced functional connectivity means brain regions that normally coordinate their activity during rest showed less synchronized activity under THC. This does not mean brain regions stopped working, but rather that their coordination was disrupted.

Did people feel the connectivity changes?

Interestingly, no. The network connectivity changes were not correlated with how intoxicated participants reported feeling, suggesting THC disrupts brain function in ways that users may not consciously perceive.

Read the original research

Δ9-Tetrahydrocannabinol Alters Limbic and Frontal Functional Brain Connectomes Among Young Adult Cannabis Users.

Biological psychiatry. Cognitive neuroscience and neuroimaging

View on PubMed ↗Publisher’s paper ↗

Citation

Anderson, Zachary; Gunn, Matthew; Jones, Emily; Ajilore, Olusola; Phan, K Luan; de Wit, Harriet; Klumpp, Heide; Calhoun, Vince; Crane, Natania A. (2025). Δ9-Tetrahydrocannabinol Alters Limbic and Frontal Functional Brain Connectomes Among Young Adult Cannabis Users.. Biological psychiatry. Cognitive neuroscience and neuroimaging. https://doi.org/10.1016/j.bpsc.2025.09.005