In a natural, expected death, people often enter a period of unresponsiveness for hours. It has always been unclear whether the brain was essentially deceased and the heart was still going for a few hours or if unresponsive dying people were aware of their surroundings. A first-of-its-kind study out of the University of British Columbia sheds new light on this question. Their results support an important recommendation in palliative care.1
Is Hearing the Last Sense One Loses When Dying?
Many hospice nurses believe that unresponsive, dying patients can still hear. Nurses report anecdotes of patients groaning or making small facial movements in response to hearing a familiar voice.2 This, perhaps combined with research involving people in a vegetative state, has led to the common belief that “hearing is the last sense to go.” The current study examines the persistence of hearing during death, but does not compare it to other senses. The researchers state that it is likely that different regions of the brain shut down at different times. However, there is actually no conclusive evidence that other senses such as touch and smell fade before hearing.
EEG Proves Hearing in Dying Patients
In the current study, Elizabeth Blundon and colleagues performed EEG (electroencephalography) studies of healthy controls, hospice patients, and those same hospice patients while they were dying. They established the brain patterns caused in response to certain tones and sound patterns. The research team found that unresponsive, dying patients showed brain patterns indicative of hearing while they were unresponsive. While their number of participants was small, there is now persuasive evidence that patients can hear within hours of death.
Are Unresponsive, Dying Patients Aware of Their Surroundings?
The function of hearing, however, does not in itself assure consciousness or awareness. The authors state that it is unknown how much cortical and sub-cortical functioning is required to support awareness. On the other hand, the similar EEG patterns between healthy controls and dying patients, even in response to subtle changes in sound patterns, suggest that dying patients do have some awareness of what they are hearing. When researchers played odd patterns, both healthy controls and dying patients showed a particular global brain activity pattern (specifically the P3b) which is normally associated with conscious detection of odd sounds. While the data is far from conclusive, it is supportive of the conclusion that unresponsive, dying patients are cognizant of sound.
Advice for End-of-Life Care
The study results support the long-standing advice to keep comforting loved ones as long as possible. One can try both touch and sound to provide comfort. It is likely that dying loved ones can hear you, even when they cannot respond.
Blundon EG, Gallagher RE, Ward LM. Electrophysiological evidence of preserved hearing at the end of life. Scientific Reports. 2020 Jun 25;10(1):1-3.
Villaneuva NE. Experiences of critical care nurses caring for unresponsive patients. Journal of Neuroscience Nursing. 1999 Aug 1;31(4):216.
Bekinschtein TA, Dehaene S, Rohaut B, Tadel F, Cohen L, Naccache L. Neural signature of the conscious processing of auditory regularities. Proceedings of the National Academy of Sciences. 2009 Feb 3;106(5):1672-7.