Dementia is caused by a range of medical conditions (the best-known being Alzheimer’s) that eat holes in the short-term memory of sufferers and degrade their capacity to process new information. Memory becomes like a flickering signal from a faraway shortwave radio station: people can do and say things, then promptly forget them, and then do and say them again. They can no longer read obvious social cues. They become easily distressed as a thickening fog descends upon them, causing them to lose track of everything. As the disease progresses, only fleeting glimpses of the once capable person can be seen; for the rest of the time, everyone is stuck with an uninvited guest. Eventually, the sufferer fails to recognise even loved ones.
Dementia raises deeply troubling issues about our obligations to care for people whose identity might have changed in the most disturbing ways. In turn, those changes challenge us to confront our philosophical and ethical assumptions about what makes up that identity in the first place. Everyone touched by the disease goes through a crash-course in the philosophy of mind.
Philosophy is not of much practical use with most illnesses but in the case of dementia it provides insights about selfhood and identity that can help us make sense of the condition and our own reactions to it. Broadly speaking, there are two accounts of how personal identity is formed and sustained. Each has different implications for how we understand dementia and so seek to care for people with it.
Our commonsense understanding of the self has been dominated by an individualistic idea that goes back to René Descartes and John Locke in the 17th century. Descartes found certainty within himself – ‘I think, therefore I am.’ The inner, mental life of the self was also grounds for knowing our experience to be real, and that we were not dreaming. Locke, for his part, identified the self with the ordered flow of sense experiences that the mind recorded. That tradition, more recently updated by the British philosopher Derek Parfit in books such asReasons and Persons (1984), argues that identity and memory come from the same place: a psychological connectedness and continuity maintained inside our heads. Selfhood hinges on our ability to order memory, and connect a set of experiences to form a coherent autobiography of who we were and how we became the person we are now. The theory has implications for dementia, because dementia destroys the temporal binding that sustains our identity.
Picture: Sanki King (File:RM-1.jpg) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons