How does CBD affect brain activity?

A new systematic review published in Frontiers in Neuroimaging (Rutledge et al., 2026) evaluated how brain-scanning research measures the effects of CBD on human brain activity.  The review synthesises existing data to inform ongoing discussions surrounding CBD’s therapeutic potential.

What is CBD?

• Screened thousands of published papers, isolating 12 qualifying studies with a total of 146 participants
• Reviewed functional neuroimaging (fMRI and SPECT) comparing brain activity after CBD administration versus a placebo
• Analysed data across both healthy individuals and participants with clinical anxiety symptoms

What the researchers did

• Screened thousands of published papers, isolating 12 qualifying studies with a total of 146 participants
• Reviewed functional neuroimaging (fMRI and SPECT) comparing brain activity after CBD administration versus a placebo
• Analysed data across both healthy individuals and participants with clinical anxiety symptoms
• The overall quality of evidence was rated low to very low

Study limitations

• Methods, dosage levels, and study groups varied widely, limiting direct comparisons
• Sample sizes were small, and several studies evaluated overlapping participant groups
• Participant demographics lacked diversity (predominantly white males), limiting broader applicability.

Key takeaways

While CBD clearly influences brain activity, existing data is insufficient to conclude that it reliably reduces stress or anxiety. The authors emphasise the need for larger, highly standardised clinical trials. Until then, medical and scientific consensus remains cautious regarding CBD’s efficacy for mood disorders.