The role of stress, inflammatory markers, and environmental determinants in cognitive decline and dementia: A systematic review of recent evidence

Cognitive decline and dementia are major public health challenges globally, with stress and inflammation emerging as significant contributors. Understanding the interplay between stress-related factors, inflammatory markers, and cognitive decline is crucial for identifying potential preventive strategies and interventions. This systematic review explored 17 studies examining the role of stress and inflammatory biomarkers (e.g., interleukin [IL]-6 and tumor necrosis factor [TNF]-α) in cognitive decline and dementia. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a thematic approach was used to analyze the findings, focusing on stress, inflammation, and their combined impact on cognitive health. Key themes identified include (1) stress as a risk factor for cognitive decline, with midlife and posttraumatic stress influencing long-term cognitive trajectories, (2) inflammatory markers such as IL-6 and TNF-α being significantly associated with accelerated cognitive decline and dementia risk, (3) lifestyle and environmental factors, including air pollution, smoking, and social determinants, exacerbating stress and inflammation, and (4) sleep quality, perceived stigma, and social networks as potential modifiers of stress-induced inflammation and cognitive impairment. The findings highlight the multifaceted interactions between stress and inflammation in cognitive decline, emphasizing the need for targeted interventions addressing stress management, lifestyle modifications, and inflammatory pathways to mitigate dementia risk. Future research should focus on longitudinal studies to establish causal relationships and develop effective prevention strategies.