You know smoking hurts your heart and your lungs. Before you light up again, consider the risk to your brain. Recent research shows that smokers have a thinner cerebral cortex, the area of the brain responsible for thinking, memory, perception, and language. If you quit smoking, some of the damage can be reversed—although it’s better not to have smoked at all. Smoking also constricts blood flow to your brain and makes your blood more prone to clotting, increasing your risk of stroke. In addition, nicotine damages the interior walls of blood vessels and makes them more susceptible to atherosclerosis (hardening of the arteries). That also increases the chance of stroke. The good news? Your body starts repairing the damage within days of that last cigarette. If you quit smoking now, you reduce your risk for dementia and other forms of cognitive decline.