Psychological, cardiovascular and haematological aspects of the type A behaviour pattern in relation to coronary heart disease

Abstract

The programme of work comprised two maj or aspects of enquiry. Firstly, the work aimed to identify specific situations which promote the Type A coping response. Secondly, the research aimed to investigate the biological mechanisms by which Type A behaviour may be translated into coronary heart disease. Specifically, the sympathetic adrenomedullary process operating via platelet and prostaglandin activity provided a major focus of the work.
Type A's (defined by both the Bortner and Thurstone Scales) have been shown to perceive performance tasks as more threatening than Type B's. not only by their enhanced cardiovascular reactivity (heart rate and systolic blood pressure), but also by their superior word recall performance. Dyadic interactive situations, in which combinations of Type A's and Type B's work together on a task, and only one member of the dyad has response control, promote intriguing behavioural, and
cardiovascular coping patterns. On a difficult task, Type A dyads (and dyads in which Type A's lacked response control) performed poorer than other dyadic combinations. Cardiovascularly, Type A's demonstrated the greater heart rate, systolic and diastolic pressure, and slower cardiovascular recovery, particularly, if they lacked control of responding, or were paired with another Type A.
A long-term naturalistic study provided validity for the acute laboratory tasks. Behavioural, cardiovascular and haematological response patterns, and the timing of reactivity, differentiated Type A's from Type B's. Whilst preparing for and following final year examinations, Type A individuals demonstrated the greater elevations in heart rate, systolic and diastolic blood pressure, plasma adrenaline and noradrenaline. They also demonstrated the faster platelet aggregation (although percentage aggregation decreased similarly for both groups), together with the greater increase in the anticoagulant, antithrombin III.
The complexity of these haenatological findings encouraged the examination of two prostaglandins which control platelet function (the coagulatory thromboxane A2 , and the anticoagulatory prostacyclin). Different response patterns emerged prior to, and following a mental arithmetic challenge. The task anticipation effect involved elevated heart rate, systolic and diastolic pressure, plasma adrenaline and prostacyclin. Type A's demonstrated the greater reactivity in all parameters. Following the task, a decrease in the percentage and speed of aggregation was recorded, together with an increase in plasma noradrenaline and thromboxane A 2 . At this stage, Type A's demonstrated the faster platelet aggregation, and the
greater noradrenai.ine levels. The thromboxane/prostacyclin ratios, however, remained similar for both groups.The Type A psychobiological response pattern, characterised by the greater magnitude and duration of potentially pathological cardiovascular and hasnatological parameters, may exert profound effects on the development of atherosclerosis and the onset of clinical coronary events.