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Meyer Friedman and his co-workers first defined personality types in the 1950s. Friedman classified people into 2 categories, Type A and Type B, and he theorized that Type A personalities had a higher risk of coronary heart disease (CHD).
Subsequent research by Dr. Redford Williams at Duke University has suggested that the risk of coronary heart problems is not specifically linked to Type A characteristics, but rather to the tendency towards hostility and anger.
Friedman and Rosenman's study Edit
Friedman and Rosenman undertook a study to understand how different types of personalities contribute to the risk of Coronary Heart Disease (CHD). (The September 2006 Public Library of Science has recently proven this not to be true) [How to reference and link to summary or text] Their hypothesis was that people who were constantly under extreme stress, always struggling to meet deadlines and people who were very driven, would have a higher chance of developing CHD than people who were more laid back and easygoing. Therefore, they put their hypothesis to a test.
First of all, Friedman and Rosenman came up with two types of personalities based on observable behaviors. The first type of personality was called Type A and it was characterized by: 1. an intense drive to achieve one’s goals 2. over-competitiveness in all areas of lives 3. constantly seeking for recognition and improvement 4. involvement in many activities at once which had deadlines to meet 5. tendency to rush things 6. astonishing physical and mental alertness. After that, the researchers came up with Type B and its characteristics were the opposites of Type A personality. Therefore, Type B people are characterized by a lack of: drive, ambition, sense of urgency, competitiveness and involvements which have deadlines.
After establishing the two types of personalities under question, they contacted various companies and asked the executives to recommend their employees that fitted either of these two types of personalities. There were 83 men in each group. The researchers then interviewed the men in each group to find out their family histories of heart trouble, their eating habits and levels of work, sleep and exercise. During the interviews, they also observed each man based on their body language and ways of speaking and categorized them under two categories: fully or partially developed pattern. Therefore, a person can be either a fully developed Type A or a partially developed Type A. It was decided that 63 out of 83 men in Type A group showed fully developed Type A pattern while 58 out of 83 men in Type B group showed fully developed Type B pattern.
The participants were then told to keep a diary of what they drank and consumed over a week. Blood was taken from all participants in order to find out the amount of blood cholesterol and the clotting time. They were also checked for arcus senilis which is a condition around the cornea of the eyes caused by the breakdown of fatty deposits in the bloodstream.
The authors analyzed the findings and found out that the overall results did not show any significant difference (only 0.1 difference) in the clotting time between Type A and Type B participants. However, they found out that the clotting time of a fully developed Type A person was 6.8 while the clotting time of fully developed Type B person was 7.2. Therefore, there was a significant difference there. The cholesterol levels of Type A people were also much higher than those of Type B people. In addition, Type A people were three times more likely to suffer from arcus senilis than Type B people. The most important finding was that 28% of Type A people suffered from CHD but only 4% of Type B people suffered from it and these Type B people showed fully developed pattern of behavior.
Therefore, the researchers’ hypothesis of which they said that Type A people were more likely to have CHD was supported. However, there were some problems with the findings. First of all, one must assume that the participants had correctly reported their dietary habits, alcohol and cigarette consumption. They were given the benefit of the doubt, but there was still some probability that they had lied. In addition, the results could also be attributed to other reasons. One was that Type A men reported a higher percentage of family members who had CHD. Therefore, the genetic inheritance of CHD might be the reason that contributed towards the disease rather than their behaviors. Furthermore, Type A men also smoked more cigarettes than Type B men and it had been scientifically proven that smoking is a direct cause of CHD. However, the researchers countered that these reasons did not have as much effect as their behaviors.
This experiment was considered a scientific breakthrough. It created a new branch of psychology called health psychology which looks at how psychological aspects of human lives affect their health. Many researchers have continued to find the link between the Type A personality and CHD. The most widely accepted reason why Type A personality people have higher risks of CHD is because these people tend to respond to stress with higher arousal, causing more secretion of adrenalin which increases heart rate and blood pressure. Therefore, Type A personality people have to try to change their behaviors, lest they risk a higher chance of heart disease.
Type D personality Edit
In a Health article, Dr. Simeon Margolis of the Johns Hopkins School of Medicine has advanced the concept the a "type D" personality, which is associated which an increased risk of heart attacks and strokes.
Citing an unnamed Dutch study, Margolis characterizes Type D personalities as those who tend to "experience negative emotions like hostility, anxiety, anger, depressed mood, tension, and a negative view of themselves." Oddly, the author of the article admits to being unaware of any definition for a possible "Type C" personality, but speculates that the D in "Type D" stands for "distressed."
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