Near-death experiences (NDEs) are episodes of disconnected consciousness with prototypical mystical features, often occurring during actual or perceived physical threat. Various explanatory theories have been proposed, but integration has been limited. Converging evidence from neuroscience—including non-human studies, psychedelic-induced mystical experiences, and research on the dying brain—now offers a comprehensive explanation. This Review discusses psychological and neurophysiological processes underlying NDEs, including cellular and electrophysiological brain network changes and neurotransmitter alterations. The authors propose a model encompassing a cascade of concomitant processes within an evolutionary framework and consider how NDE research informs debates on consciousness emergence near brain death.
Psychosis in Parkinson disease (PDP) includes illusions, hallucinations, and delusions that can appear even early in the disease. While once thought to be solely a side effect of dopaminergic drugs, evidence now shows PDP results from the disease's own brain changes combined with medication. Dysfunction in attentional control, sensory processing, limbic structures, the default mode network, and thalamocortical connections leads to incorrect categorization of stimuli and false percepts. This review covers recent clinical, neuroimaging, and neurochemical findings that may help identify psychotic phenomena early and guide new treatments.