Unexpected cognitive lucidity and communication in patients with severe dementias, especially around the time of death, have been observed and reported anecdotally. Here, we review what is known about this phenomenon, related phenomena that provide insight into potential mechanisms, ethical implications, and methodologic considerations for systematic investigation. We conclude that paradoxical lucidity, if systematically confirmed, challenges current assumptions and highlights the possibility of network‐level return of cognitive function in cases of severe dementias, which can provide insight into both underlying neurobiology and future therapeutic possibilities.

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The aim of this research was to study paradoxical lucidity-the unexpected return of cognition and communication in patients with diagnosed dementia-systematically in a contemporary sample. We conducted a survey of caregivers who had witnessed at least one case of paradoxical lucidity in the year prior to survey completion. We assessed diagnosis and degree of preexisting cognitive impairment, cognitive state during the lucid episode, and temporal proximity of the lucid episode to death. Detailed case reports of 124 dementia patients who experienced an episode of paradoxical lucidity were received. In more than 80% of these cases, complete remission with return of memory, orientation, and responsive verbal ability was reported by observers of the lucid episode. The majority of patients died within hours to days after the episode. Further prospective study is warranted, as paradoxical lucidity suggests that there may exist a reversible and functional aspect of pathophysiology in severe dementia.

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