Moments of sudden, clear communication in someone with progressive neurodegenerative disease are episodes of what researchers call “paradoxical lucidity.”

“A person seems to be lost to their disease, but then there’s this unexpected and fleeting spark of clarity,” says Andrew Peterson, a philosopher for the Penn Program on Precision Medicine for the Brain (P3MB) who studies paradoxical lucidity. “It could transform the way we think about dementia.” 

Paradoxical lucidity seems to be, as its name suggests, a paradox. How can a person living with advanced dementia abruptly communicate in a clear manner? Many wonder what mechanism underlies this phenomenon and if it might be a key to mitigating—or even reversing—neurodegeneration. It’s also a mystery whether people who exhibit these episodes are aware when they happen, and how that might affect dementia care.

Peterson says these pressing questions cannot be accurately addressed by scientists until a definition is established—a main point of Peterson and his P3MB colleagues’ recent article “What is paradoxical lucidity? The answer begins with its definition,” published in Alzheimer’s & Dementia. Peterson explains that the paper establishes a framework for future research.

“It’s not as simple as putting someone in a brain scanner or video recording someone having a moment of paradoxical lucidity. Researchers still haven’t come to a consensus as to what the behavior looks like.” says Peterson. “We need a good clinical characterization of the behavior before we can examine what’s happening in the brain.”

Because paradoxical lucidity is a relatively new area of research, scientists do not have a precise estimate of how frequently it occurs in persons living with dementia. Penn Memory Center co-director Jason Karlawish, who leads P3MB, said he suspects episodes of paradoxical lucidity are fairly common.

“Most, if not all, clinicians have heard stories of events of paradoxical lucidity,” says Karlawish.

Karlawish and Peterson are currently leading an NIA-funded study to better understand paradoxical lucidity’s clinical characterization. They want to discover how witnessing an episode of paradoxical lucidity impacts family caregivers.

“The experience of caregivers of persons living with dementia who witness paradox lucidity is similar to families of unconscious brain injury patients” says Peterson. “In both cases, families are struggling with uncertainty. An unexpected change in a patient’s behavior can lead families to think their loved one is still ‘in there’. That can impact the grieving process and change how they understand the disease.”

As a philosopher, Peterson says forging the frontier of research on paradoxical lucidity is “one of those critical instances” where philosophy and science can work hand in hand.

This story is by Cait Kearney. Read more at Penn Memory Center.