"Paradoxical Lucidity" -- dying patients with severe dementia suddenly regain lucidity and communications

The idea that someone with severe dementia would suddenly regain both lucidity and speech just before death seems terribly strange and challenges our understanding of how the brain functions when afflicted by disease.  There has been no systematic study of this phenomenon, but examples have been widely reported anecdotally.  An article in this weeks issue of Alzheimer's and Dementia the Journal of the Alzheimer's Association provided a survey of reports of such events and discussed their significance.  The article was "Paradoxical lucidity: A potential paradigm shift for the neurobiology and treatment of severe dementias." 

The article took the reports seriously and considered them likely related to near-death experiences.  It also considered that studying the phenomenon may find that AD is not completely irreversible.  

The article did not attempt to discern any new understanding about the phenomenon, but it discussed how a serious investigation should be conducted.  It also discussed insights that such an investigation might provide with respect to how the brain functions and what AD actually does to it.

This reminded me of something I'd seen recently regarding "functional MRIs" of the brain.  These produce the images you see of brains with colors denoting the level of neuronal activity in various regions.  However, what the MRI is actually measuring is blood flow and also oxygen content of the hemoglobin.  When neurons are "firing" they need extra energy and so need more glucose from blood.  Blood flow is increased in areas of neuronal activity.  It's like a microprocessor in your computer that needs more electrical energy when it works harder, and you can hear the cooling fan speed up as the computer works harder.  Increased blood flow is then a proxy for neuronal activity.  The computer can help us visualize what's going on with the neurons by adding color to areas with varying blood flow.

What I saw recently was work with people whose brains had no electrical activity -- they were "brain dead."  However, a functional MRI would still detect changes in blood flow within the brain when complete, meaningful sentences were spoken to the person.  But blood flow would not change when the same words were spoken to the person in a nonsensical sequence.  The assumption is that the parts of the brain that take in audio signals and interpret them no longer function, but somehow the brain is still trying to do that.  To some this suggests that, while the mind is intimately interconnected with the brain and is involved in brain activity, it nevertheless has a separate existence from the brain.  Is that what it means?  I'm not sure what to make of it.