Factors Contributing to Cognitive Decline Remain a Mystery to Scientists

Researchers examined common risk factors associated with cognitive decline and found that they may not be as influential on cognitive functioning as previously thought. However, some factors, such as education level, were linked to better cognitive function.

Current estimates indicate that more than 55 million people live with dementia worldwide. Moreover, almost 10 million people are diagnosed with the condition every year.

Despite volumes of research investigating the potential factors associated with cognitive impairment, scientists still don’t know what contributes to declines in cognitive functioning and the development of neurodegenerative diseases such as dementia or Alzheimer’s.

For example, a study published on February 8 in the journal PLOS ONE found that factors typically associated with cognitive decline didn’t explain the variations in cognitive function among middle-aged and older adults.

The study, conducted by researchers from Ohio State University and the University of Michigan, used data from 7,068 participants in the 1996 to 2016 Health and Retirement Study. The researchers assessed common risk factors and obtained the participant’s cognitive functioning measurements at age 54 and then observed how it declined until they reached age 85.

After analyzing the data, the scientists found the following:

• Better socioeconomic status in adulthood, including education, occupation, income, and wealth, was associated with better cognitive functioning at age 54 and a slower decline in cognitive functioning later. However, the most significant predictor of cognitive functioning at age 54 was education level.
• Years of education were not significantly associated with variations in cognitive functioning, but participants with a college degree had a slower cognitive decline than those without a degree.
• Obesity and smoking were linked to lower cognitive functioning. In addition, diabetes, heart disease, and psychiatric conditions were also associated with cognitive decline.

Still, all the individual factors examined explained only 38% of the variation in cognitive decline among the participants — leaving no clear answers about what factors contribute to dementia.

The scientists note that the most interesting finding is how those with a college degree experienced less cognitive decline.

"College may provide an especially rich environment for cognitive development beyond pre-college education. College education also increases one’s life expectations and incentives to engage in healthier behaviors, leads to occupations with more mental stimulations, and is very consequential for one’s income and higher quality of social connections," the authors wrote.

In the end, the scientists say that more research is urgently needed to discover the determining factors of cognitive decline to slow down the progression of cognitive impairment and dementia.