Writing in the journal Neurochemistry International, researchers from the University of Reading, UK, provided a recent overview of the role of inflammation in cognitive impairment and the cellular mechanisms at work, highlighting the therapeutic potential of nutraceuticals along inflammatory pathways.
These include vitamins, omega-3 fatty acids, amino acids, polyphenols, prebiotics and probiotics, which have been extensively studied for their anti-inflammatory properties—where nutraceuticals are defined as natural or processed substances that provide health benefits to prevent chronic diseases.
Inflammation and cognitive decline
Both acute and chronic inflammation can impair cognitive function by damaging neurons and synapses, disrupting blood flow to the brain and affecting neurotransmitter signaling.
Past studies correlate elevated inflammatory markers and a decline in cognitive function, particularly in aging-associated neuroinflammatory conditions, the researchers noted.
“The primary mechanism involves the response of microglia, an immune cell in the brain, which generates pro-inflammatory mediators such as cytokines, chemokines and adhesion molecules,” they explained.
“The excessive production of pro-inflammatory mediators may accelerate the damage to neurons, contributing to the development of neurodegenerative diseases such as Alzheimer’s disease, mild cognitive impairment and vascular dementia, as well as a general decline in cognitive function.”
Their investigation evaluated evidence from original studies and meta-analyses to suggest how a selection of nutraceuticals might influence relevant biological cellular processes and inflammatory biomarkers.
Promising biomarkers and nutraceuticals
According to the literature reviewed, “suppressing microglia activation, attenuating cytokine expression and inhibiting upstream signaling molecules may be suggested as primary targets to manipulate neuroinflammation-related cognitive impairment.”
The researchers found strong evidence linking pro-inflammatory markers—such as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and interleukin-1 receptor antagonist (IL-1RA)—to cognitive impairment, particularly in memory. Higher levels of acute inflammatory markers, including C-reactive protein (CRP), IL-6 and S-100β, were also consistently associated with a higher risk of post-operative cognitive dysfunction (POCD).
For chronic low-grade inflammation, meta-analyses consistently support a link between elevated inflammatory biomarkers like CRP and IL-6, both in the brain and periphery, with cognitive impairment across various health conditions.
“Even though there have been some inconsistencies, this review strongly suggests that elevated inflammatory status is associated with cognitive dysfunction in humans,” the researchers concluded. “Therefore, to reduce the likelihood of impairment of cognitive function, anti-inflammatory interventions, either drug-based or other alternative approaches, such as nutrients, non-nutrient bioactive compounds and exercise, could be considered to prevent the development of inflammation related to brain pathologies.”
Nutraceutical candidates identified included folic acid alone or in combination with vitamin B12, amino acids and peptides like chicken hydrolysate and anserine/carnosine, long chain omega-3 fatty acids, polyphenols such as anthocyanins and curcumin, as well as probiotics that target the increasingly studied gut-brain axis.
The researchers called for further exploration of the specific domains of cognition and cut-offs for concentration of inflammatory markers related to cognitive decline to develop targeted interventions.
Source: Neurochemistry International
“An overview of the relationship between inflammation and cognitive function in humans, molecular pathways and the impact of nutraceuticals”
doi: 10.1016/j.neuint.2024.105900
Authors: Chusana Mekhora et al.
