If you're in your 50s and your typical day involves sitting at a desk followed by lounging on the sofa and succumbing to late-night snacks, the long-term toll on your mind might be greater than you think.
Like dominoes, an unhealthy lifestyle can trigger inflammation throughout your body, which can then accelerate wear-and-tear on your brain, a new study suggests.
The result? Faster declines in thinking and memory for folks who don't practice healthy habits that counteract inflammation.
Long-term inflammation is most often caused by chronic health problems such as obesity, diabetes and heart disease, said lead researcher Keenan Walker. He is a postdoctoral fellow of neurology with Johns Hopkins University in Baltimore.
"We found that people in their middle adulthood who had higher levels of inflammatory markers in their blood tended to decline over the next 20 years at a quicker rate, especially on measures of memory," Walker said.
Regular exercise, a heart-healthy diet and good sleep could be important factors in staving off age-related declines in brain function, the study authors concluded.
"If someone becomes really sick, they tend to have changes in behavior," Walker explained. "Even with just a common cold, people have different behavior. They're less likely to want to do anything, they lose motivation. They become less hungry. Sometimes they experience changes in mood. Those are all examples of systemic inflammation in the body affecting how the brain functions."
Given that, it's possible that long-term chronic inflammation could have longer-lasting effects on brain health.
To test that notion, the research team gathered data on more than 12,300 people participating in a long-term study of heart health problems. The participants, with an average age of 57, were followed for about two decades.
As part of the study, researchers took blood samples and measured four different markers of inflammation. They combined the four to come up with a composite inflammation score for each person.
Participants' thinking and memory skills also were tested at the beginning and end of the study, according to the report.
The group of people with the highest inflammation scores had an 8 percent steeper decline in thinking and memory skills over the course of the study, compared with those who had the lowest inflammation, the findings showed.
Walker called the influence of chronic inflammation on thinking and memory skills "modest," but added that it was more powerful than the effect found in previous studies of middle-aged high blood pressure on brain function later in life.
This could be happening either because chronic inflammation is directly harming neurons, or because it is exacerbating other brain conditions that contribute to Alzheimer's disease or dementia, Walker said.
However, people shouldn't start taking anti-inflammatory meds like aspirin or ibuprofen on the assumption that the drugs will protect their brain health, warned Walker and Mary Sano, director of the Alzheimer's Disease Research Center at the Icahn School of Medicine at Mount Sinai in New York City.
Sano said, "There have been many studies examining anti-inflammatory agents in cognitive [thinking] diseases over the years, and the results have been modest to unimpressive."
Rather, it shows the potential lifelong importance of reducing inflammation in your body by staying on top of chronic health conditions and living a healthy lifestyle, Walker and Sano said.
"One of my common comments to people is to treat your treatable conditions," Sano said. "If you reduce the inflammatory effects broadly, you may also reduce their effects on cognition."
Neither Sano nor Walker felt that any age would be too late to start eating right, exercising and controlling chronic disease.
"I think earlier typically is better," Walker said, "but I'm aware of studies that have shown improved diet and exercise can positively impact cognitive health even among older adults."
The findings were published online Feb. 13 in the journal Neurology.
Johns Hopkins has more about chronic inflammation.