Could an inability to read increase the chances of dementia? A new study published in the journal Neurology found that older people who could not read or write were between two and three times more likely to develop dementia than those who are fully literate.
Jennifier Manly, professor of neuropsychology at Columbia University College of Physicians and Surgeons, New York and lead researcher of the study said: "Our findings provide strong evidence of a link between illiteracy and the risk of dementia.”
Characteristics of dementia include issues with problem-solving, slowed thinking, focus and organisational skills, along with chronic or persistent memory loss. This condition is more common in older people, but it is not just an older person’s disease. According to research from Alzheimer’s Society, UK, there were 42,325 people diagnosed with early-onset dementia (on set before the age of 65) living in the UK in 2013.
For the purpose of the study, researchers focused on around 1,000 men and women over the age of 65. The average age of participants was 77. Most had been born and raised in rural areas of the Dominican Republic before moving to northern Manhattan, USA. None of the participating volunteers, including those who could read or write, had attended school for more than four years.
Experts followed the participants in three separate groups for an average of four years. The first group was created in 1992, the second in 1999, and the third in 2009, involving a total of 983 people. Each group member was medically examined every 18 to 24 months, as well as given memory tests to complete, along with language and other skills-based tests.
Why it is important to know how to read
Among the participants who were classified as illiterate, more than one-third (35%) already had dementia when the longitudinal study commenced. By comparison, only 18% of literate participants had dementia at that time.
After taking into account variable factors such as age, income, and genetic history of heart disease, the team concluded that illiterate people were three times more likely to have developed dementia at the start of the research project than their literate counterparts.
Researchers found, by the end of the research period almost half (48%) of people classified as illiterate had developed dementia. Whereas among the literate participants, only 27% developed dementia like symptoms and problems linked to memory loss.
The researchers concluded that, under equal conditions, and after taking into account age, socio-economic status, and risks relating to heart disease, being illiterate almost tripled the chances of developing dementia.
Research Jennifer Manly said: "Even if people only have access to a few years of education, people who learn to read and write may have lifelong advantages over people who never learn these skills."
What is it about reading and writing that seems to protect us from dementia?
Manley explained: "Being able to read and write allows people to engage more often in what we could call 'cognitively enriching' activities.
"In other words, activities that 'exercise' the brain, like reading newspapers and books, helping children and grandchildren with their homework, or getting a job that requires literacy. Learning to read and write allows a person to participate in these activities all throughout their lifetime."
This study is not definitive proof that being illiterate actively increases the risk of dementia, but does suggest a strong correlation between reading and writing ability with dementia symptoms. There are some extenuating circumstances, such as why a person has never learned to read or write, which can influence the long-term risk of dementia.
One limitation of the study was that the researchers did not ask how or when the literate study participants learned to read and write.
The scientists say the next step would be to investigate whether tackling illiteracy might be a way to reduce dementia risk.
Exploring ways to lower the risk of dementia are vital. Statistics from the World Health Organisation (WHO) state that there are at least 10 million new cases of dementia across the world, every year - with numbers likely to rise.
Reference: 'Illiteracy, dementia risk, and cognitive trajectories among older adults with low education', American Academy of Neurology, 2019.