As the flame of consciousness flickers and fades during the final hours of a person’s life, their brain continues to process sound in the same way as that of a younger person who is still full of beans, according to a new study in the journal Scientific Reports. This finding suggests that words spoken to an unresponsive loved one as they lie on their deathbed may not fall on deaf ears, and could help to comfort them as they slip away.
The study authors used electroencephalography (EEG) to monitor activity in the brains of unconscious patients in the final hours of their life at a hospice in Vancouver, and compared this to EEG readings from other hospice patients who were still conscious, as well as a healthy control group.
Each group was played a series of tones in a recurring pattern, but with occasional notes that didn’t follow the general trend. The researchers were looking for particular brain signals – known as the MMN, P3a and P3b signals – that are known to occur in the brain when it notices anomalous sounds.
Reporting their findings, the researchers note that “most unresponsive patients showed evidence of MMN responses to tone changes, and some showed a P3a or P3b response to either tone or pattern changes. Thus, their auditory systems were responding similarly to those of young, healthy controls just hours from end of life.”
However, while the brains of these dying individuals may still have been able to recognize certain sounds in the moments before death, it is not clear whether a person in this state can consciously register words or meanings. In a statement, study author Elizabeth Blundon explained that participants’ “brains responded to the auditory stimuli, but we can’t possibly know if they’re remembering, identifying voices, or understanding language.”
In spite of this, co-author Romayne Gallagher insists that “this research gives credence to the fact that hospice nurses and physicians noticed that the sounds of loved ones helped comfort people when they were dying.
“And to me, it adds significant meaning to the last days and hours of life and shows that being present, in person or by phone, is meaningful. It is a comfort to be able to say goodbye and express love.”