Monomeric [CRP] and CRP-Controlled Stress and Pain Hypersensitization as Novel Predictors of Cognitive Disturbance and AD in Chronic Inflammatory Disease

Chronic low-grade systemic inflammation is increasingly recognized as a key mediator linking stress, pain sensitivity, and cognitive decline. Central to this process are the acute-phase reactants interleukin-6 (IL-6) and C-reactive protein (CRP), which serve as biomarkers of systemic inflammation while promoting neuroimmune dysregulation. Emerging evidence implicates the IL-6–CRP axis in the amplification of pain perception, central sensitization, and stress hypersensitivity, ultimately promoting neurodegenerative processes such as those observed in Alzheimer’s disease (AD) and vascular dementia. Monomeric CRP (mCRP), a proinflammatory isoform generated under mechanical or oxidative stress, can trigger histone modifications (e.g., H3 citrullination), activate endothelial and immune cells, and exacerbate inflammatory pain pathways. These mechanisms are further modulated by genetic and epigenetic factors, including IL-6/CRP/NR3C1 gene variant expression; promoter methylation; and stress-responsive microRNAs, which intersect with dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, impairing immune resolution and neurocognitive resilience. Psychosocial stressors, such as the burden of caregiving or perfectionistic cognitive patterns, amplify IL-6 and CRP levels, particularly when pain is present, suggesting a synergistic interaction between emotional distress and somatic inflammation. Specifically, elevated CRP is associated with increased pain sensitivity, lower pain thresholds, and cognitive decline even in subclinical populations, providing a feedforward model in which chronic stress and pain potentiate systemic inflammation, disrupt neuroendocrine feedback, and accelerate neurodegenerative pathology. However, in this model, the potentially critical mechanistic and pathological role of mCRP remains to be discovered. This review addresses the missing elements of these overlapping pathways and discusses the therapeutic potential of targeting IL-6–CRP signaling, stress regulation, and epigenetic modifiers as strategies to ameliorate inflammation-driven cognitive decline and enhance stress resistance in chronic disease contexts. We propose that plasma mCRP or more likely the isoform-aware metric, the mCRP/CRP ratio, will provide a biologically anchored, potentially more discriminative approach to vascular-neuroimmune risk and capture the propensity for local effector signaling, likely outperforming hs-CRP or IL-6 alone for risk stratification across neurovascular and stress-sensitized pain phenotypes.