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Inflammation's Link to Alzheimer's, Heart Disease and Cancer

Mounting evidence reveals the connection, but lifestyle changes may help

By Holly Lawrence

Despite its heroic intentions to protect us against foreign invaders, inflammation also plays a role in many diseases, especially those experienced by older adults. Doctors and researchers around the world and across disease categories have caught on, and they’re working on ways to tame the beast of chronic inflammation.

“More than 90 percent of all noncommunicable diseases of aging are associated with chronic inflammation,” David Furman of Stanford Medical School’s Institute for Immunity, Transplantation and Infection explained upon the release of a study on caffeine consumption and inflammation.

More than 1,000 papers have provided evidence that chronic inflammation contributes to many cancers, Alzheimer’s disease and other dementias, cardiovascular disease, osteoarthritis and even depression, Furman said in a Stanford news release.

Through his research of age-related neurologic diseases, scientist Joseph Rogers of the nonprofit research institute SRI International has shown that inflammatory responses occur in almost all major age-related brain disorders and cause substantial damage.

The Up Side of Inflammation

The targets of inflammation’s wrath include bacteria, abnormal toxins and molecules that are detected in any part of our body.

“Inflammation is always a two-headed sword,” said Rogers in HBO Documentary Films’ The Alzheimer's Project. “It destroys, and that’s beneficial. When you have foreign invaders, inflammation destroys those foreign invaders. The problem is, it can also destroy healthy tissue in the process. So, you’ve got to be very careful about that.”

Dr. Luigi Ferrucci, scientific director of the National Institute on Aging, told Next Avenue: “Unfortunately, and for reasons that we do not understand, the inflammation that is linked to aging — the mild pro-inflammatory state of aging — remains there, does not fade, and therefore, damage is accumulated in the absence of repair and maintenance.”

Alzheimer’s and Inflammation

“It is now unquestioned that inflammatory reactions occur in the Alzheimer’s disease brain,” Rogers said in an interview. “They are readily and universally detected in brain tissue from virtually all autopsied Alzheimer’s patients and, more recently, have been emphasized in genetic studies covering as many as 100,000 or more Alzheimer’s victims and normal elderly controls.”

Rogers indicated that there is some new, but still unconfirmed, evidence that a foreign pathogen may be involved. But he said that a “molecule called amyloid-beta peptide that is produced by the patient’s own brain cells is the clearest stimulus for inflammation in the Alzheimer’s brain.”

In the HBO documentary, Rogers explained, “Amyloid beta peptide is clearly abnormal — it’s almost like a splinter in your brain, and you’ve got thousands of them and so you’re going to have an inflammatory attack as the microglia, inflammatory cells in the brain, move in and try to get that out of the brain. “

Still No Treatments

Rogers said multiple anti-inflammatory drugs have been tested with little to no positive effects.

He offered these two possible explanations:

  • Dozens of different inflammatory mechanisms that are known to occur in Alzheimer’s disease  Which one should we treat? Would a single target do any good if so many others still remained intact?
  • Timing of treatment Amyloid beta deposition and inflammation are known to occur as much as a decade or more before patients start to exhibit symptoms. Some two dozen studies have suggested, in fact, that people who take significant doses of anti-inflammatory drugs are less likely to develop Alzheimer’s, but only if the drugs are taken early.

Obstacles in Preventive Clinical Studies

Clinical studies studying prevention of Alzheimer’s disease are “horribly expensive” compared with studies on treatments for those who already have the disease, Rogers said. Prevention studies involve recruiting thousands of healthy older adults and tracking them for many years in order to see who develops the disease and who doesn’t when given the drug.

For that reason, funding agencies and drug companies are reluctant to bankroll the prevention studies, he said.

Inflammation and Cancer

In a 2016 study published in Cell Reports, UCLA researchers found high numbers of a type of cell in the inflamed areas of the prostate gland. This new evidence links chronic prostate inflammation and increased risk for prostate cancer, the leading cause of cancer in men.

Last month, another UCLA-led study, published in Cancer Epidemiology, Biomarkers & Prevention, found that an unhealthy, high inflammatory diet during adolescence and early adulthood may increase a woman’s risk of breast cancer later in life.

And the National Cancer Institute website said that over time, inflammation can cause DNA to become damaged and lead to cancer. “For example, people with chronic inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, have an increased risk of colon cancer,” the institute said.

Diet is an important factor in cancer prevention, said Stephanie Maxson, senior clinical dietitian at MD Anderson’s Integrative Medicine Center, on the hospital's website. “Prolonged inflammation can damage your body’s healthy cells and tissue, and weaken your immune system,” Maxson said. This weakened state can increase your risk of diseases like cancer, the article said.


Inflammation and Heart Disease

A study published in the Journal of Psychiatric Research by researchers at the University of California, San Francisco, found a link between poor sleep quality and cardiovascular disease. They noted that inflammation levels caused by poor sleep could increase more in women who have heart disease than in men.

“Inflammation is a well-known predictor of cardiovascular health,” researcher Aric Prather said when the study was published.

Dr. Deepak L. Bhatt, executive director of Interventional Cardiovascular Programs, Brigham and Women’s Hospital Heart & Vascular Center, said in an interview: “Chronic cardiovascular inflammation is associated with a greater risk of heart attacks and strokes.”

Bhatt explained that “many conventional cardiovascular risk factors appear to trigger inflammation. For example, elevated levels of cholesterol and plaque build-up in a heart artery trigger inflammatory cells to respond, further damaging the artery and predisposing (a person) to a heart attack.”

Bhatt added, “It is a bit of a chicken and egg story. That is, cardiovascular risk factors promote chronic inflammation, which in turn can predispose to heart disease. So, heart disease can cause inflammation, but inflammation can also contribute to heart disease.”

How Can We Prevent Inflammation?

Harvard Medical School’s Harvard Health Letter described in 2006 what research showed at the time: that chronic inflammation may be the “unifying theory of disease.”

The authors described how inflammation interacts with cancer, diabetes, coronary artery disease and Alzheimer’s, and offered “commonsense health practices” for preventing inflammation.

Now almost 11 years later, evidence has mounted from studies in these and other disease areas. Suggestions for prevention — proper diet, exercise, no smoking, regular checkups — have remained unchanged.

And there's one prescription that may be easy for many to swallow: more coffee. A study by Stanford University School of Medicine showed that caffeine intake may help control chronic inflammation.

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Holly Lawrence is a freelance writer on well-being and issues affecting older adults. Connect on LinkedIn. Read More
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