July 10, 2024
Increasingly, doctors recognize that persistent, body-wide inflammation plays a role in many diseases of aging, including heart disease, diabetes, arthritis and Alzheimer’s disease. But chronic inflammation isn’t just a condition afflicting people over 50. A new study found that people in their 20s and 30s can also have high levels of persistent, low-grade inflammation, setting the stage for deficits in memory and thinking skills in middle age and an increased risk of dementia later in life.
Chronic inflammation isn’t something you necessarily see or feel. It is a kind of simmering, low-grade irritant that can slowly and silently damage organs throughout the body, the result of a poorly regulated immune system. As we grow older, levels of body-wide inflammation tend to rise and can take a toll on virtually all parts of the body, including the brain.
“Late-life inflammation has been linked to dementia risk and the earliest signs of cognitive decline, but less is known about inflammation in young adults,” said study author Dr. Kristine Yaffe of the University of California, San Francisco. “Our study found that having consistently higher or moderate inflammation starting in early adulthood may negatively affect a person’s ability to plan, focus and manage multiple tasks as well as how quickly they can process information in middle age.” The findings were published in Neurology, the medical journal of the American Academy of Neurology.
For the study, Dr. Yaffe and her colleagues followed 2,364 men and women aged 24 to 58 over more than two decades. All were part of a long-running study called the Coronary Artery Risk Development in Young Adults study.
To assess inflammation levels, researchers measured blood levels of a substance called C-reactive protein, or CRP. C-reactive protein is produced by the liver, and rising levels indicate higher levels of inflammation. Researchers measured CRP levels at the start of the study period, and again three more times over the next 18 years.
Five years after the last CRP measurement, study volunteers completed tests of memory and thinking skills. Participants who were initially in their 20s or early 30s at the start of the study were now in their 40s or 50s.
The researchers found that compared to those who had low inflammation levels as young adults, those with moderate or high inflammation levels in their 20s or 30s tended to perform worse on cognitive tests in middle age. They tended to have slower brain processing speeds and did worse on tests of executive function. Executive function allows people to focus on tasks, remember names and numbers, and behave accordingly to the situation at hand. It becomes increasingly impaired as Alzheimer’s disease progresses.
“Inflammation is important for cognitive aging and may begin much earlier than previously known,” said Dr. Yaffe. “Although current prevention efforts mainly focus on late life, our study provides evidence for the need to also target brain health in middle age.”
The finding showed only a correlation between inflammation and brain aging and does not prove cause and effect. But numerous large studies in older men and women have shown similar links between high levels of inflammation and an increased risk of Alzheimer’s disease and other diseases of older age.
Fortunately, there are steps you can take to minimize, and possibly even reverse, the progression of chronic inflammation. All these measures have been linked to a lower risk of Alzheimer’s disease as well.
- Eat a heart-healthy diet. The Mediterranean diet, rich in fruits, vegetables, healthy fats like olive oil, fish and whole grains, contains nutrients that fight inflammation. Coffee and tea may also have anti-inflammatory effects. Ultra-processed foods high in refined carbohydrates and added sugars, on the other hand, tend to promote inflammation.
- Get regular exercise. Both aerobic exercise and weight training can lower levels of inflammatory compounds over the long term.
- Minimize stress. Chronic stress also contributes to inflammation. Meditation, yoga, tai chi and other practices can help to lower stress levels and bring down levels of inflammatory proteins.
- Prioritize sound sleep. People who are sleep deprived or have irregular sleep schedules are more likely to have higher levels of inflammation. Scientists believe that sleep has cleansing properties that rid the brain of toxic proteins, including those that build up in people with Alzheimer’s disease.
Reactions from our Researchers:
“This study clearly shows a link between systemic inflammation and the risk of developing neurodegenerative diseases like Alzheimer’s. However, important questions remain: First, whether inflammation plays a role to initiate, accelerate or amplify neurodegeneration. Second, mechanisms by which systemic inflammation induces neurodegeneration remains to be fully understood and if it may act directly through the activation of microglia or other cells, which in turn might release factors that induce toxicity of neurons. Understanding these questions may shed light on new therapeutic approaches to prevent or slow down the progression of Alzheimer’s. Meanwhile, we should try, as much as possible, to avoid risk factors that are presented here by enjoying a healthy life which may benefit the entire population beyond Alzheimer’s disease.”
Dr. Olivier Hermine, MD, PhD
Laboratory Director at Imagine Institute, Paris, France
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Amber L. Bahorik, PhD; Tina D. Hoang, MSPH; David R. Jacobs, PhD; Kristine Yaffe, MD: “Association of Changes in C-Reactive Protein Level Trajectories Through Early Adulthood With Cognitive Function at Midlife: The CARDIA Study.” Neurology, July 3, 2024
Eleanor L.S. Conole, PhD: “Chronic Inflammation and Brain Health: The Case for Early Monitoring (editorial).” Neurology, July 3, 2024
