Near-death experiences may occur in more than one-third of patients who survive cardiac arrest, according to a scoping review of 11 prospective studies from various countries. The incidence ranged from 6.3% to 39.3%, varying between in-hospital (6.3–39.3%) and out-of-hospital (18.9–21.2%) cardiac arrest. Reported content of these experiences often reflected the language of the questionnaires used rather than participants' own words. Three studies that conducted follow-up all suggested a positive life attitude change, but one found significantly higher 30-day all-cause mortality in patients with near-death experiences versus those without, in non-controlled analysis. Lasting effects may be confounded by clinical characteristics.
Adenosine signaling is the common mechanism underlying rapid-acting antidepressant therapies, including ketamine, electroconvulsive therapy (ECT), and acute intermittent hypoxia. Using genetically encoded sensors and mechanistic experiments, the study shows that all three treatments induce adenosine surges in mood-regulatory circuits via A1 and A2A receptor activation. Ketamine's mechanism primarily involves modulation of mitochondrial metabolism rather than NMDA receptor antagonism, suggesting potential for improved derivatives with better therapeutic indices. These findings provide a framework for evaluating therapeutic benefit in depression and raise questions about caffeine consumption in treatment-resistant depression—whether chronic use protects against or acute use impedes treatment response.