Near-death experiences (NDEs) are conscious perceptual experiences involving self-related emotional, spiritual, and mystical feelings that can occur in close encounters with death or in non-life-threatening situations. Their origin remains unknown. Recent prospective studies confirm that NDEs represent a spectrum of highly distinctive memories associated with negative or positive emotions, influenced by the causal event, though the temporal sequence of images varies. Some drugs, particularly ketamine, can produce experiences similar or identical to NDEs. New models extend previous neural network theories and incorporate evolutionary and quantum aspects. While NDEs' factual existence is no longer doubted and their semiology is well-described, a comprehensive pathophysiological model is still lacking.
In a double-blind, placebo-controlled trial, 50 intensive care unit patients with acute disorders of consciousness after brain injury received apomorphine, methylphenidate, or placebo. Automated pupillometry measured pupillary responses to verbal commands; neither drug significantly increased these responses overall. However, 20% of patients showed improved clinical arousal at least once after drug administration, with methylphenidate linked to more arousal events than placebo. Patients with greater baseline pupillary responsiveness were more likely to show arousal, suggesting this may predict stimulant effects. No adverse events occurred. The findings need replication but may guide future trials on consciousness recovery.