People with Type D personality are distressed. They tend to experience negative emotions and keep these emotions inside, not sharing them with others. Personality traits such as these are considered stable over time. As would be expected, Type D individuals with cardiovascular disease have a poor prognosis. Heather Tulloch, PhD, psychologist in the Prevention & Rehabilitation group, looked at the impact of cardiac rehabilitation on these individuals. She found that, after three months of rehabilitation, Type D patients exhibited a significant drop in social inhibition and reporting of negative emotions. Rehabilitation provided attitudinal benefits to these individuals, causing a shift in what would be expected to be a stable aspect of their personalities. This challenges the idea that the Type D categorization is actually a stable one.