Inflammation and memory

Chronic inflammation in middle age can lead to cognitive problems in old age

Lina Medvedeva, XX2 century

Inflammation is divided into acute and chronic. Acute inflammation occurs when the body develops an immune response to fight infection or injury. Acute inflammation is localized, short-lived and is a sign of a healthy immune system. Chronic inflammation cannot be considered healthy. This is a mild inflammation that lasts for months or even years. It can be caused by an autoimmune disease, such as rheumatoid arthritis or multiple sclerosis, as well as physical stress. Symptoms of chronic inflammation include joint pain, digestive problems, and fatigue.

Ways to reduce chronic inflammation are regular physical exercise, an anti-inflammatory diet for the heart, sufficient sleep.

"Chronic inflammation affects the body and can damage joints, internal organs, tissues and cells," says first author of the study Keenan A. Walker, Ph.D. at Johns Hopkins University. – It can also lead to diseases of the cardiovascular system, strokes and cancers. Similar studies have dealt with chronic inflammation and its effect on the brain in elderly people, but we turned to an extensive study of chronic inflammation in middle age and showed that it can affect cognitive decline several decades later, in old age."

The study of this problem was part of the study of the risk of atherosclerosis in various communities (Atherosclerosis Risk in Communities, ARIC), scientists for 20 years followed 12336 people whose average age was 57 years. The researchers took blood samples from the subjects at the beginning of the study and measured 4 biomarkers of inflammation: fibrinogen, leukocyte levels in the blood, von Willebrand factor and blood clotting factor. A summary scale of inflammation with four biomarkers was created. Three years later, the researchers measured C-reactive protein, another blood biomarker of inflammation. Participants were divided into four groups based on summary data on inflammation and C-reactive protein levels.

Participants' memory and thinking skills were tested at the beginning of the study, then after a period of six to nine years and at the end of the study.

The researchers identified the group with the highest rates of inflammation biomarkers, where there was a sharp 8% deterioration in memory and thinking skills throughout the study, in contrast to the group with the lowest level of inflammation biomarkers. The group with the highest C-reactive protein had a 12% more pronounced drop in the level of these skills than the group with the lowest. These results were adjusted for other factors affecting memory and thinking skills, such as education level, heart failure and high blood pressure. Further analysis revealed that the weakening of thinking associated with inflammatory processes was most noticeable in memory when compared with other aspects of thinking, such as language and executive functions.

Article Systemic inflammation during midlife and cognitive change over 20 years The ARIC Study published on the website of the journal Neurology.

"Thus, the additional change in thinking and memory skills associated with chronic inflammation was unnoticeable, but it turned out to be stronger than previously attributed to high blood pressure in middle age," says Walker. – Most of the processes that lead to deterioration of memory and thinking skills occur in middle age, and it is in middle age that they may be most susceptible to intervention.  Our results show that chronic inflammation can be a serious reason for intervention. However, it is possible that chronic inflammation is not the cause, but a marker, or even a reaction to neurodegenerative brain diseases that lead to cognitive changes."

The limitation of the study lies in the fact that participants with a higher level of chronic inflammation at the beginning of the study were more likely to leave it or die before the final control visit, so the survival rate of participants may not be representative of the general population.

Future research may include more frequent examinations of memory and thinking skills. They should also study more markers of inflammation in the blood.

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