LSD produces marked changes in brain activity that correlate with its psychological effects. Increased blood flow in the visual cortex, decreased alpha power there, and an expanded functional connectivity profile of the primary visual cortex strongly correlated with visual hallucinations, suggesting that intrinsic brain activity influences visual processing more during the psychedelic state. Decreased connectivity between the parahippocampus and retrosplenial cortex correlated strongly with ego-dissolution and altered meaning, indicating this circuit's role in maintaining the self and processing meaning. Different imaging metrics showed strong relationships, allowing firmer inferences about their functional significance.
A group retreat model of psilocybin therapy for people with metastatic cancer and anxiety or depression was safe and well tolerated. Fifty-two participants attended a 3-day retreat with 25 mg psilocybin, supported by virtual and in-person sessions. No episodes of unattended distress occurred during the psilocybin sessions. Anxiety and depression symptoms, measured by the Hospital Anxiety and Depression Scale, decreased by an average of 7.3 points from baseline to 28 days after the retreat, a statistically significant reduction. The findings suggest that a group configuration of eight participants with four core facilitators can be safe for future studies in people with serious medical illness.
Lysergic acid diethylamide (LSD) in microgram doses produces profound, sometimes life-changing experiences and is a uniquely powerful psychoactive substance. In the first modern neuroimaging study of LSD, marked changes in brain blood flow, electrical activity, and network communication patterns were observed. These changes correlated strongly with the drug's hallucinatory and consciousness-altering properties. The findings have implications for understanding the neurobiology of consciousness and for potential applications of LSD in psychological research.