terminal lucidity

There are various neurological conditions which are thought to be non-reversible, conditions such as dementia and Alzheimer’s.  But there is anecdotal evidence dating from the late 1800s of patients who experience a reversal of their symptoms so that they can suddenly remember people, speak clearly, and display lucid thinking.  For some patients this period of lucidity, in some cases a matter of hours, in others lasting up to a week, is followed by death.  In some cases a patient has a moment of lucidity and then lapses back into the previous state, in which case the name given to it is paradoxical lucidity, paradoxical because such a reversal is not meant to be possible.

There are obvious difficulties in studying terminal lucidity so that there is no understanding of what the condition is, who may be subject to it and who may not, and how it could possibly happen.  Added to this is the complication of medication which can obscure such moments of lucidity. There are also legal implications.  Can instructions given when the patient was clearly of sound mind be overridden by instructions given in this moment of apparent lucidity? And there is the effect on the family who may see this moment of lucidity as a possible restoration of health rather than as a harbinger of death.