Ketamine and psychedelics can alter markers of synaptic density, which may relate to their abuse liability and potential therapeutic effects in substance use disorders. A scoping review of 84 studies found mixed results for ketamine: single or repeated doses under basal conditions produced inconsistent synaptic changes in the hippocampus and prefrontal cortex, but a single dose counteracted stress-related reductions in these markers, and repeated dosing also reversed stress effects. Psychedelics generally increased synaptic markers, though results varied by agent. The heterogeneity likely stems from differences in methods, drugs, sex, and marker types.
Music mindfulness—combining music listening with mindfulness activities—acutely increases heart rate variability and alters brain activity in frontotemporal regions, as measured by wearable electrocardiography and electroencephalography in people with moderate anxiety and depression. Both live and virtual sessions reduce stress and shift state of consciousness, but only live sessions enhance social connection. Effects on physiology and psychology differ by self-reported sex. The findings suggest music mindfulness engages autonomic and neural mechanisms that may help treat anxiety and depression symptoms.