Higher education may reduce risk of dementia

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A study in Japan found a link between higher education and reduced risk of dementia. Helen Cortez/EyeEm/Getty Images
  • Researchers investigated how rates of dementia and frailty in Japan will change over time. 
  • They found that educational attainment may predict dementia risk. 
  • The researchers concluded that public health policy should address sex and educational disparities in comorbid dementia and frailty to prepare for population aging. 

Japan has the oldest population in the world. In 2021, around 29.2% of its population, about 36 million people, were over 65, and an estimated 3.5 million have dementia. In 2012, 3 million were estimated to have frailty.

By 2050, 16% of the global population will be over 65 years old, compared to just 8% in 2010. As the population ages, researchers expect corresponding increases in dementia and frailty. 

Foreseeing how disease burden may increase alongside population aging could help policymakers improve healthcare for the elderly. 

Recently, researchers created a microsimulation to predict how dementia, frailty, and life expectancy rates will change in Japan by 2043. 

Scott Kaiser, MD, Director of Geriatric Cognitive Health for the Pacific Neuroscience Institute, CA, not involved in the study, told Medical News Today

“The simulation highlighted that […] drastic increases in dementia need not be an inevitable byproduct of an aging population.” 

“The simulation also highlighted deep inequities that must be addressed to prepare for an aging population,” he added. 

The study was published in the Lancet

Microsimulation

For the study, the researchers used a newly-developed microsimulation model to predict rates of frailty and dementia among the elderly by 2043. 

They built their model from nationwide cross-sectional surveys, death records, and existing cohort studies.

Their data included age, sex, educational attainment, and health indicators, including: 

  • Incidence of 11 chronic diseases, including heart disease, diabetes, and cancer
  • Incidence of depression
  • Function in day-to-day life
  • Self-reported health

The researchers noted that life expectancy might increase from 23.7 years in 2016 to 24.9 years in 2043 after age 65 for women and 18.7 years to 19.9 years for men. 

Over the same period, years spent with dementia are expected to decrease from 4.7 to 3.9 years in women and 2.2 to 1.4 years in men. 

This change, they say, may be explained as the model predicted mild cognitive impairment to begin later in life than at present. 

However, they also found that rates of frailty will increase from 3.7 years to 4 years among women and 1.9 to 2.1 years for men across all educational groups. 

They also found that age, gender, and education affect rates of frailty and dementia. 

They found that by 2043 28.7% of women over 75 years old who do not have a high school education will have both frailty and dementia and thus require complex care. 

Meanwhile, only 6.5% of women aged 75 and above with a college education or higher are expected to have frailty. 

Less dementia 

To understand why dementia rates may decrease over time in Japan, MNT spoke with Dr. Hideki Hashimoto, DPH, a professor at the Department of Health and Social Behavior at the University of Tokyo, and a co-author of the study.

Dr. Hashimoto said that increasing educational attainment might be an important factor in explaining reduced dementia rates overall. He noted that, by 2035, over 60% of men would be college graduates. Meanwhile, in 2016, just 43% of men ages 55- 64 were college-educated. 

He added that an Organization for Economic Co-operation and Development (OECD) Adult Skills Survey published in 2013 found that those with high school diplomas in Japan have more work-relevant skills than college graduates in Europe and the US. 

Dr. Hashimoto thus concludes that the ‘unique educational background change’ is likely a major contributor to his model’s results. 

Preventing dementia

When asked how these results could inform other countries concerning dementia in an aging population, Dr. Kaiser told MNT that the findings highlight public health planning efforts to address modifiable risk factors across the lifespan.

“Experts believe that something on the order of 1 out of 3 cases of dementia could be prevented through addressing twelve “modifiable risk factors” for dementia (low education, hypertension, hearing impairment, smoking, midlife obesity, depression, physical inactivity, diabetes, social isolation, excessive alcohol consumption, head injury, and air pollution),” he explained. 

“Likewise, along with population-level efforts to prevent dementia, a focus on early detection for earlier intervention could significantly mitigate the impact and extend healthy years. One of the greatest myths about Alzheimer’s disease (or other types of dementia) is that there’s “nothing we can do. [But there’s] nothing could be further from the truth,” he said. 

“The wide range of modifiable risk factors noted, and even our relationships or levels of loneliness, can be addressed as part of a multimodal strategy in people with early cognitive changes that may delay the onset or severity of dementia symptoms,” he added. 

The researchers concluded that public health policy should address sex and educational disparities in comorbid dementia and frailty to prepare for population aging. 

When asked about the study’s limitations, Dr. Hashimoto said that their model could not account for behavioral risk factors such as smoking, exercise, and dietary habits, which have a major impact on health and aging. 

He added that their findings could not explain why and how education levels affect dementia prevalence. 

Dr. Kaiser added that the model could not account for the possibility of continued innovation and efforts to prevent, treat or even cure dementia in the future.