Dementia is a progressive and irreversible disease that may affect 75 million people by 2030. Patients with dementia lose their memory, ability for self-care, and their independence. However, for many years, there have been reports of terminally ill patients with severe end-stage dementia who have experienced an unexpected return of mental lucidity for a short period of time, especially near the end of life. This has been observed in other terminally ill patients who have also lost their cognitive functions. These episodes of lucidity are called paradoxical lucidity.

During these episodes, people who were unable to recognize loved ones, recall memories from their past, or lose the ability to effectively communicate with others for many months or years, may suddenly and unexpectedly regain signs of lucid behaviors. These include the ability to speak full sentences, appropriately respond to yes or no questions, regain the ability to walk, recognize family members, or describe seeing someone from their past. For instance, “A woman aged 92 who had been diagnosed with Alzheimer’s disease for 9 years and did not recognize close family members, including her son, recognized them again 24 hours before she died. Moreover, she knew how old she was and where she was, which she had not known for many years.” (Grosso, 2004)

Although very little is known about these episodes, the ability to regain previously lost behaviors or mental clarity, for even a short period of time, suggests there may be some aspects of dementia that are reversible. Because this information could potentially provide future treatment options, researchers in the Parnia Lab are conducting a five-year study to better understand why these events occur.

This study will help build a scientific definition and measurement tool for future research. The purpose of this study is to describe and understand periods of mental clarity in people with severe dementia near the end of life. We hope to better understand why and how these episodes of mental clarity occur and learn more about whether dementia is truly an irreversible disease.