Here is a statistic that is both disturbing and encouraging. Forty-five percent of cases of dementia are potentially preventable. However, the study in the journal Cerebral Cortex suggests simple lifestyle choices could prevent them. Australian researchers say a group of healthy older adults in the study all had normal memory, thinking skills and cognitive function. What varied were their scores on dementia risk, calculated from modifiable health and lifestyle habits such as physical activity, sleep, social engagement and diet. Researchers discovered specific patterns in individual brain chemistry were linked to the dementia test. Higher risk scores were linked to lower levels of three chemicals in the brain that help ability to property regulate itself.