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Key Study: Stress and the
Western Collaborative Group Study

Meyer Friedman and Ray Rosenman (1959, 1974)

1 March 2013

AIMS: To investigate the hypothesis that the development of coronary heart disease (CHD) was associated with Type A behaviour.

Friedman & Rosenman, from their work as cardiologists, noted that their patients displayed a common behaviour pattern: they were goal-oriented, driven, competitive, impatient and hostile. These characteristics, it was hypothesised, would lead to both raised blood pressure and raised levels of stress hormones, both of which are linked with illness.

The Western Collaborative Group Study was set up to test Friedman & Rosenman’s hypothesis.

PROCEDURE (METHOD): The participants were a self-selected sample of nearly 3,200 male participants, between the ages of 39-59 and living in the San Franciso Bay Area. This was a prospective, longitudinal study as the participants were healthy at the outset, having been screened for signs of CHD, and were assessed over period of 8.5 years.

Part 1 of the study included structured interview and observation which assessed personality type and current health status. Personality type was determined by the amount of impatience, competitiveness and hostility reported and observed during the interview and from the answers to 25 questions concerned with how the individual responded to everyday life. Eg:  the intervieqwee was asked how they would cope with having to wait in a long queue. The interview was conducted in a provocative manner – ie: interrupting the interviewee - to try and elicit Type A responses. Loudness and speed of talking were considered in particular.

The participants were then classified on a scale: A1 (fully Type A), A2 (not fully Type A), X (equal amounts Type A and Type B, or B (fully Type B) – Type B being more relaxed individuals in comparison to the high stress Type A.

Part 2 of the study was the follow-up 8.5 years later when incidence of CHD was recorded.

A correlational analysis was carried out to test the association between Type A/B behaviour and CHD.

Type A

Type B

Heart attacks



Recurring heart attacks



Fatal heart attacks



RESULTS (FINDINGS): After 8.5 years 257 of the original participants had developed CHD. Of those 257, 70% were identified as being Type A. This was nearly 2 x as many as Type B, even when other factors associated with CHD – eg: smoking, obesity and existing high blood pressure – were taken into account. More than twice as many Type As had died of cardiovascular problems as Type Bs. 12% of Type As had experienced a heart attack, compared to just 6% of the Type Bs.

Type As were found to have higher levels of cholesterol, adrenaline and noradrenaline and higher blood pressure than Type Bs. They were also identified as more likely to be engaged in risky behaviours such as smoking.

A moderate but significant correlation was found between personality type and CHD.

CONCLUSIONS: Friedman & Rosenman found that Type A behaviour is fairly strongly linked to  CHD. They concluded that Type A behaviour increases the individual’s experience of stress which increases physiological reactivity which, in turn, increases vulnerability to CHD. The high levels of stress hormones suggest Type As do experience more stress than Type Bs. The stress response inhibits digestion which leads to higher levels of cholesterol in the blood.