- A new study links inflammation to the development of Alzheimer’s disease and dementia.
- Alzheimer’s Disease and other forms of dementia affect millions of Americans.
- Biomarkers for inflammation were linked to higher risk of dementia.
The medical community has increasingly identified the role of inflammation in the development of Alzheimer’s Disease and dementia — now a new study from the UK further establishes that link.
Despite the prevalence of dementia among the elderly and its burden on the healthcare system (costing hundreds of billions of dollars each year), researchers have yet to determine a clear cause of the disease. The greatest known risk factor for Alzheimer’s disease is aging, but there is also a cluster of other risk factors identified as potential causes, including genetic predisposition, inflammation, cardiovascular health, and brain chemistry (plaques and tangles). Isolating a single or predominant cause of the disease has proved difficult; finding a cure has proved even more elusive.
Biomarkers show inflammation’s effect on dementia risk
A new study from the UK, published July 19 in the journal PLOS ONE, sheds light on the link between inflammation, cognition, and dementia. Utilizing health data from over 500,000 individuals, obtained through the large, population-based study, the UK Biobank (UKB), researchers were able to take large amounts of data and compare them with cognitive outcomes and dementia risk. Specifically, researchers looked at certain blood biomarkers indicative of inflammation and how these correlated with various cognitive tasks. They found a small, but statistically significant, association between higher levels of these biomarkers, worse cognitive performance, and higher risk of dementia later in life.
“Elevated levels of blood inflammatory markers are often found in elderly individuals and this condition is termed ‘inflammageing.’ Inflammageing carries a high susceptibility to chronic diseases and premature death. We found associations between elevated systemic inflammation biomarker levels, concurrent and later cognitive performance, and future dementia risk,” Dr. Krisztina Mekli, lead author of the study and a genetic researcher at the University of Manchester, told Healthline.
For the UKB, more than a half-million participants willingly consented to have their health information used for scientific and research purposes. The cohort included both men and women, recruited between 2006-2010, and were between 40-69 years old at the time. Participants in the UKB were also included as part of a longitudinal study that followed them over the course of years to capture any subsequent health events.
Mekli and her team sifted through massive amounts of data to look at one specific question: does the presence of certain inflammatory biomarkers affect cognitive ability and dementia risk.
They found that the answer was yes.
Dr. Paul Newhouse, Director of the Center for Cognitive Medicine in the Department of Psychiatry at Vanderbilt University Medical Center, who was not affiliated with the study, told Healthline, “What this work suggests is that even in a very large study, they can show a small but measurable effect of chronic low-level inflammatory markers in the body.”
Highest inflammatory markers linked to 35% increased dementia risk
Members of the UKB cohort were asked to take part in a series of cognitive tests, designed to test different forms of brain function: things like memory and reaction time.
To measure different aspects of cognitive functioning, researchers employed a series of different kinds of tests. For reaction time, individuals were told to press a button as soon as they saw two matching cards appear on a screen. For memory, they were asked to remember the location of matching pairs of cards; they were also given strings of numbers, beginning with two digits and progressing up to twelve digits, and asked to input those strings of numbers. Logic and reasoning questions were employed to test “fluid intelligence.”
“Literature indicates that tests of specific domains, such as episodic memory, executive function, verbal fluency, and processing speed are predictors of dementia. The cognitive tests in UKB were designed to be brief and to tap into cognitive domains that are sensitive to ageing and/or pathological processes,” Dr. Mekli told Healthline.
With the exception of the “pair matching” exercise, individuals with higher levels of inflammation biomarkers exhibited “increasingly worse” performance in each of the cognitive exercises. Even more startling, those with the highest levels of biomarkers were found to have a 35% increased risk of dementia diagnosis compared to those with the lowest levels of biomarkers.
Is all inflammation bad?
Not exactly. Inflammation is actually a good thing; it is an integral part of the body’s immune system response. “Inflammation is necessary to get rid of an infection or acute injury. If you get a cut on your hand, you’ll get inflammatory cells that come there, but you don’t want them to stay there,” said Newhouse. But that’s often what happens in the aging process: inflammation just kind of hangs around, as a chronic low-grade inflammation in the body.
The term “inflammageing” was coined to refer to the, “age-related increase in the levels of pro-inflammatory markers in blood and tissues.” When inflammation doesn’t go away, like it does when it is done fighting an infection, and instead becomes chronic, it plays a role in the development of a host of diseases from cancer and osteoporosis, to heart problems and dementia.
There’s no simple cure for inflammation and, by extension, dementia either, but both Mekli and Newhouse suggest that lifestyle changes like eating healthier and exercising more often are a good place to start.
“There is data emerging that certain dietary and physical activity efforts can have a positive effect on inflammation,” said Newhouse, “We do believe that regular physical exercise actually can tamp down inflammation in a systemic way.”
A new study finds that people with biomarkers that signal higher levels of inflammation had a higher risk of dementia.