This document discusses the links between diet, brain health, and cognitive decline such as Alzheimer's disease. It explains that a poor diet high in refined foods and sugars can cause inflammation and insulin resistance, reducing brain-derived neurotrophic factor levels and impairing brain chemistry. This increases the risk of depression, cognitive decline, and other mental health issues. In contrast, a Mediterranean-style diet rich in fruits, vegetables, whole grains and omega-3 fatty acids promotes brain and gut health by reducing inflammation and oxidative stress. Maintaining a healthy diet and lifestyle is important for preventing cognitive decline and disease in older adults.