Researchers at University College London found that ongoing negative thinking can increase the risk of developing Alzheimer’s disease. Nearly 300 people over the age of 55 were monitored in order to determine how much they dwell on negative past experiences or worry about the future. Approximately half of participants were also given PET scans to measure deposits of tau and amyloid, two proteins that build up in the brain to cause Alzheimer’s. Overall, several years of study produced results similar to other studies that have shown that people who maintain a positive attitude live longer and maintain better overall mental health. In contrast, chronic negative thinking over long periods of time increases the risk of heart attack, stroke and early death.