Research conducted by scientists from UC San Francisco has shown that young people with higher levels of inflammation, which are associated with obesity, physical inactivity, chronic diseases, stress, and smoking, may experience a decline in cognitive function in middle age.

Scientists have previously linked higher levels of inflammation in older adults with dementia, but this is one of the first studies to connect early adulthood inflammation with lower cognitive abilities in middle age.

The Importance of Long-Term Health Habits
Amber Bahorik, Ph.D., from the Department of Psychiatry and Behavioral Sciences and the Weill Institute for Neurosciences at UCSF, stated: “We know from long-term studies that changes in the brain leading to Alzheimer’s disease and other dementias can last for decades. We wanted to investigate whether health and lifestyle habits in early adulthood affect cognitive skills in middle age, which could influence the likelihood of dementia later in life.”

The research, published in the journal Neurology on July 3rd, showed that only 10% of those with low levels of inflammation performed poorly on speed and memory tests, compared to 21% and 19% of those with moderate or high levels of inflammation.

Research Findings
When the scientists adjusted the results for factors such as age, physical activity, and total cholesterol, differences in processing speed remained; differences in executive functions, which include working memory, problem-solving, and impulse control, were also observed.

The study followed 2364 adults as part of the CARDIA study, which aims to identify factors in early adulthood that lead to cardiovascular disease two to three decades later.

Participants were between 18 and 30 years old when they entered the study and were tested four times over 18 years for the inflammation marker C-reactive protein (CRP). Cognitive tests were conducted five years after their last CRP measurement, by which time most participants were in their forties and fifties.

About half of the participants were female; slightly less than half were African American, and the rest were white. Around 45% had lower stable levels of inflammation, while 16% had moderate or rising levels of inflammation; 39% had higher levels.

The Link Between Inflammation and Health Risks
Scientists also linked higher levels of inflammation with physical inactivity, higher body mass index (BMI), and current smoking.

“Inflammation plays a significant role in brain aging and can begin as early as early adulthood,” said lead author Kristine Yaffe, M.D., a professor of psychiatry and behavioral sciences, neurology, and epidemiology and biostatistics at UCSF. “There is likely a direct and indirect effect of inflammation on cognition.”

Yaffe is a member of the first team of experts to determine that 30% of the risk for dementia can be prevented. Her recent research examined the association between fragmented sleep and lower cognition in middle age and the effects of personalized health and lifestyle changes in preventing memory loss in older adults at higher risk.

“Fortunately, there are ways to reduce inflammation – such as increasing physical activity and quitting smoking – that could be promising pathways for prevention,” Yaffe said.

Source: University of California