RadioLab discusses how the final novels of Agatha Christie subtly reflected the early stages of dementia as her written vocabulary and her ability to use the nuances of language slowly began to diminish.
The discussion is based on a linguistic analysis of her books by English professor Ian Lancashire who found in his study [pdf] that the range of vocabulary in her final works markedly declined and her use of indefinite words (like ‘something’ or ‘anything’) greatly increased, indicating that her striking ability to manipulate the English language was fading as she began to develop dementia.
This is not the first analysis that has looked at the literary output of a great author as she declined. A 2005 study analysed the text of three Iris Murdoch books, who famously lost her literary abilities as Alzheimer’s disease began to take hold, and found a similar pattern in her later writing.
In the case of Murdoch, and probably in the case of Christie, both of these analyses were on books completed before the authors were diagnosed with the condition (although we don’t know if Christie was ever formally diagnosed owing to the secrecy of her family).
In fact, we know that this is a common pattern, in that years before people get diagnosed with Alzheimer’s disease there is a slow but steady decline of mental function that is a little beyond what we would expect from normal ageing but not so severe that it is clear the person has the condition.
The RadioLab programme also discusses the well-known ‘Nun Study‘ project which has studied the relationship between biological and life-style factors and the risk of getting Alzheimer’s disease in a group of nuns.
In one of the studies from the project, the researchers found a link between getting Alzheimer’s and the linguistic skills of the nuns that they demonstrated in an essay they wrote when they first entered the convent as young women – those who wrote the more complex essays were less likely to develop the dementia later in life.
This reflects an idea in dementia research known as the ‘cognitive reserve‘ which suggests that your mental ability is a bit like a fuel tank and when wear-and-tear on the brain drags your ability below a critical point in later life, you start going into the rapid decline of dementia.
Those with more mental ability are therefore more resistant (although not immune) to dementia. While level of education has been consistently linked to protection against dementia, it could just be that those who have more natural mental capacity study more, but there is some recent research that suggests education may help ‘top up’ the cognitive reserve fuel tank to help protect against the disease.
Link to RadioLab piece ‘Vanishing Words’.