Delta-9-tetrahydrocannabinol, the active compound in cannabis, temporarily alters how brain regions communicate with each other. In 19 occasional cannabis users who underwent two resting-state fMRI scans—one shortly after smoking a cannabis cigarette and one after at least a week without cannabis—a transient connectivity state appeared only during intoxication. This state showed high connectivity within and between auditory and somato-motor cortices, along with anti-correlation with subcortical structures and the cerebellum. Subjective perceptual changes and THC plasma levels were linked to this state, suggesting a neural biomarker of cannabis intoxication.
Intranasal esketamine substantially reduced depression severity in 210 patients with treatment-resistant depression treated in routine clinical practice. Depression scores improved markedly over three months, and men showed a modest advantage over women by the end of treatment, with lower depression ratings and higher rates of response and remission. Among patients under 65 years, sex differences were small and not statistically significant; among those 65 and older, men appeared to benefit more numerically, but this difference did not hold up after statistical correction and remains uncertain. Discontinuation rates and safety outcomes were similar between sexes. The authors call for future studies to examine hormonal, vascular, inflammatory, and other factors that might explain the observed sex differences.