Chronic stress, gut dysbiosis, and cholesterol metabolism: Implications for Alzheimer's disease.

Alzheimer's disease is a degenerative neurological condition that gradually worsens and is the predominant type of dementia evident in millions of individuals globally. The intricate origin and development of this condition includes multiple genetic and environmental risk factors, alterations in gene expression, and activation of detrimental pathways. Chronic stress can adversely affect brain structure and function, leading to diminished cognitive ability, impaired decision-making, and poor mood regulation. The gut-brain axis, influenced by dietary and early life variables, significantly affects the control of stress responses. The human microbiota forms a symbiotic interaction with the host, impacting protective cell barriers, metabolic processes, and immune functions in the intestines. Chronic stress and high-cholesterol diets can alter gut microbiota composition, influencing behaviour, immune responses, and intestinal function. Oxysterols affect gut health and inflammation through the alteration of tight junctions and the stimulation of proinflammatory bacterial proliferation. This review provides a thorough explanation of the structure and function of the dietary stress system, its relationship with the central nervous system (CNS) and endocrine axis, and evidence connecting stress to the core processes of stress-related illnesses impacting AD. A thorough comprehension of the complex interplay among chronic stress, gut dysbiosis, and Alzheimer's disease progression could provide novel insights for the formulation of targeted therapeutic interventions.