When you hear about high blood sugar, what comes to mind? Diabetes risk, weight gain, and maybe a risk to heart health? But what about your brain? High blood sugar—even below diabetes levels—may boost the risk of dementia. A new study from University College London in the United Kingdom found that “prediabetes”—a condition where blood sugar levels are high but not as high as full-blown diabetes—may threaten brain health. The research was published in the journal Diabetes, Obesity, and Metabolism. Looking at data from the UK Biobank on a half-million people between the ages of 40 and 69, researchers found people with prediabetes had a 42 percent higher risk of mental decline over four years than people with normal blood sugar. They were 54 percent more likely to develop vascular dementia, a common type of dementia resulting from reduced blood flow to the brain, over eight years. Researchers found no …