The document outlines 9 habits that can damage the brain: 1) Not eating breakfast lowers blood sugar and nutrients to the brain. 2) Overeating causes hardening of brain arteries and lower mental power. 3) Smoking causes brain shrinkage and may lead to Alzheimer's. 4) Too much sugar interrupts nutrient absorption and brain development. 5) Air pollution decreases oxygen to the brain, lowering efficiency. 6) Sleep deprivation accelerates brain cell death. 7) Sleeping with your head covered reduces oxygen and increases carbon dioxide in the brain. 8) Working the brain while ill can damage it and lower effectiveness. 9) Lacking stimulating thoughts may cause brain shrinkage.