As we age, our brains become more prone to inflammation, even without a specific underlying issue. This ongoing, low-level inflammation is linked to memory loss and brain diseases.
Inflammation is a natural process in a healthy brain serving as a defense mechanism to protect against injury or infection, controlled by small immune cells called microglia. When microglia are at rest, they clean up waste, maintain balance, and monitor the brain. However, when there is an injury, infection, or disease, microglia shift their focus from cleaning to addressing the more immediate problem. They cause and regulate inflammation. Proper cleaning can wait until after the "war"—when the disease is over. But, like every war, even this one has collateral damage, such as harm to neuronal cells. Activated microglia release pro-inflammatory molecules that can trigger a cascade of immune responses, potentially leading to neuronal damage (1). Temporary brain fog and slower processing, due to the buildup of debris in the brain, can occur as a result. This is a small, temporary price to pay, as once the problem is resolved, microglia return to their cleaning duties and quickly catch up on overdue work. Everything returns to normal—this is a healthy response ensuring long-term stability.
However, with age or prolonged stress, microglia become less effective (2). When stress and age combine, significant problems are inevitable. Microglia become primed for activation, which causes a sharp inflammatory response even in the absence of an actual problem. This leads to ongoing inflammation, which can start a chain of immune responses that harm the brain. If there is no "enemy" and no real problem, whom do your microglia fight? Your brain! Microglia, like people, can only focus on one thing at a time—either maintaining a healthy brain or fighting a "war." While inflammation is a healthy response, chronic low-level inflammation is disastrous. This persistent, low-grade inflammation, often termed "inflammaging," is responsible for cognitive decline and neurodegenerative disorders (3).
With lifestyle interventions, such as paying attention to our diet, we can influence the level of inflammation in our brains (4). Certain nutrients, including omega-3 fatty acids found in fish oil, are known to have anti-inflammatory properties, leading to improved cognitive function (5, 6). Curcuminoids, found in turmeric (Curcuma longa), are also known to effectively reduce inflammation. However, when it comes to the brain, they do not naturally cross the blood-brain barrier (BBB), the brain's gateway and part of its protection system (similar to borders with customs control). Curcuminoids need scientific assistance to disperse and be absorbed effectively. Similarly, polyphenols like quercetin, fisetin, and other antioxidants like vitamin C, found in fruits and vegetables, can reduce the levels of free radicals in cells and, consequently, lower brain inflammation (7).
In summary, understanding how microglia cause brain inflammation and how this changes with age is key to maintaining brain health. A diet rich in anti-inflammatory nutrients can help reduce harmful inflammation and support long-term brain health
Koellhoffer EC, McCullough LD, Ritzel RM. Old Maids: Aging and Its Impact on Microglia Function. Int J Mol Sci. 2017 Apr 5;18(4):769. doi: 10.3390/ijms18040769. PMID: 28379162; PMCID: PMC5412353.
Kunnumakkara AB, Hegde M, Parama D, Girisa S, Kumar A, Daimary UD, Garodia P, Yenisetti SC, Oommen OV, Aggarwal BB. Role of Turmeric and Curcumin in Prevention and Treatment of Chronic Diseases: Lessons Learned from Clinical Trials. ACS Pharmacol Transl Sci. 2023 Mar 6;6(4):447-518. doi: 10.1021/acsptsci.2c00012. PMID: 37082752; PMCID: PMC10111629.
