In the field of gerontology, there is a question regarding whether certain diseases can accelerate the progression of other diseases. Given that there is no existing cure for dementia, there is an undeniable upsurge in demand for research concerning identifying preventive measures that influence the onset or development of cognitive decline. Cerebral atherosclerosis is characterized by the thickening of artery walls within the brain. Many studies have shifted their focus on examining the role nutrients and food play in preventing cognitive decline, dementia, cerebral atherosclerosis, and Alzheimer’s disease (AD). This thesis provides a comprehensive overview of existing observational and clinical trial evidence published up to date for the association of dietary intervention between cognitive health, dementia, AD, and cerebral atherosclerosis.