Lucidity in Dementia

Abstract: The phenomenon of “lucidity” in disorders leading to dementia, which has been occasionally reported in Alzheimers disease (AD), is an intriguing one. It is relevant to the degree to which information encoding personal identity in these disorders is “lost” as opposed to “hiding,” and could also be relevant to treatment. But to what degree is it true? First Published: 3/23/14. Last Major Update: 3/23/14.

Breaking Lucidity Down 

From the various reports I’ve read on forums and in articles, “lucidity” seems to be colloquially composed of:

  • a) demonstrations of personality (e.g., a witty remark)
  • b) demonstrations of memory (e.g., remembering someone’s name)
  • c) demonstrations of energy and/or activity (e.g., talkativeness)
  • d) demonstrations of awareness of one’s condition (this can often lead to fear and anxiety or occasional thankfulness to caregivers)

The personality and memory components are more central to the notion of personal identity.

Promoting Lucidity

Some reports indicate that lucidity in patients with dementia can be promoted in various ways:

  • Playing music (e.g., an RCT vs recreational therapy here, though see here for an RCT with no effect on cognition)
  • Exercise (e.g., see case report here, though see here for an RCT with no effect on cognition)
  • Being near to death (i.e. “terminal lucidity”; e.g., see review of case studies here)

Behavior Underestimates

One key point to make is that any moments of lucidity demonstrating personal identity are almost certainly a lower bound on what is actually retained. That is, there are a variety of ways that people with dementia could have more knowledge and retention of personal identity than others notice that they do. For example, patients could have speech problems, or could lack small but crucial “pieces of the puzzle” while retaining most of the other details.

Here’s an interesting article of a pianist with Alzheimer’s disease who had retained episodic memory for music.

Relevant Brain Networks 

First of all, why do we care about the brain regions? Because it offers us a way to potentially measure the presence or absence of lucidity without the behavior via brain imaging.

With that out of the way, here are some candidates:

  • Brain regions that are upregulated during lucid dreaming (e.g., the precuneus, see here)
  • Brain regions that are involved in the lateral and medial parietal and hippocampus (see here and here for a nice summary)