Personality refers to the particular combination of emotional, attitudinal and behavioural response patterns of an individual. It is broad as people behave consistently across situations. A trait is a stable characteristic. A state is temporary. Personality traits appear to influence exposure to health-relevant social circumstances rather than simply moderate reactions to other influences on health.

Cloninger Temperament and Character Inventory distinguish several temperaments (i.e. inherited traits):

1. Novelty seeking
   This is exploratory activity in novel situations.
2. Harm avoidance
   This is worrying, pessimism and shyness.
3. Reward dependence
   This is being highly responsive to reward.
4. Persistence
   This is the ability to persevere in spite of fatigue or adversity.

There are also several character traits (i.e. shaped by the environment):

1. Self-directedness
   The ability to self-direct behaviour toward a goal.
2. Cooperativeness
   This refers to being agreeable versus self-centred.
3. Self-transcendence
   This refers to the experience of being part of something greater.

The Big Five Personality traits distinguish five different personality traits:

1. Neuroticism
   This refers to experiencing negative affectivity.
2. Extraversion
   This refers to being outgoing rather than introverted.
3. Openness to experience
   This refers to being inventive, curious rather than consistent and cautious.
4. Conscientiousness
   This refers to being careful and organized.
5. Agreeableness
   This refers to being cooperative, considerate and kind.

Neuroticism is associated with the presence of somatic complaints. It comprises anxiety (1), depressive symptoms (2), worry (3), anger (4), irritability (5), self-consciousness (6) and low self-esteem (7). It is often accompanied by distress.

The interpersonal approach to personality assumes an inherent association between personality and social circumstances. Intraindividual factors (e.g. goals; expectancies) guide overt social behaviour. This leads people to behave in a way that is consistent with these factors, leading to stability of reciprocal interaction patterns. Personality can influence the frequency (1), magnitude (2) and duration of exposure to stressors in daily life (3). It is also possible that personality influences health through the influence on health behaviours.

Optimism refers to the tendency to hold optimistic expectations about the future and this is associated with better health (1) and fewer complications (2). It is not the same as the absence of pessimism.

Hostility refers to the tendency to experience anger and hold cynical or suspicious beliefs. It is related to atherosclerosis, CHD and mortality. Hostility is associated with more all-cause mortality. Type A behaviour (i.e. hostility and dominance) is related to coronary heart disease. Hostility and anger lead to a larger cardiovascular and neuroendocrine response to stressors. These effects are stronger for the development of the disease than the course of the disease.

It is also possible that people with a type-A personality select more challenging tasks and evoke more competitive and antagonistic behaviour from others. Hostile individuals respond to stressors with larger and more prolonged heart rate (1), blood pressure (2) and endocrine changes (3). It is also associated with inflammatory markers.

Type-D personality is a combination of people who score high on negative affectivity and social inhibition. It is genetically determined and stable over time. Different unique environmental factors influence type-D personality.

Emotion-focused coping skills are aimed at reducing distress. Problem-focused coping skills are aimed at solving the problem at hand. Type-D personality is associated with maladaptive coping strategies. People with type-D personality have lower self-esteem (1), have an inferior body image (2) and a diminished sense of personal accomplishment (3). They more often have a preoccupied or fearful attachment style.

The tendency to minimize negative emotions (e.g. repressive coping) is associated with increased risk of cancer (1), cancer progression (2) and hypertension (3). The health consequences of repressive coping could be due to stress moderation mechanisms. Repressive coping is associated with more stressful social interactions and other interpersonal difficulties.

The difference between depression and type D personality is that type-D personality is very stable (1), includes social inhibition (2) and is about negative affect in general (3). Chronic anxiety and depression are associated with increased exposure to daily stressors and future life difficulties.

Hopelessness is associated with:

• The tendency to develop hypertension.
• Increased incidence of death from cardiovascular disease and cancer.
• Greater progression of atherosclerosis.
• Reduced longevity.

The health behaviour model states that personality can influence illness through health behaviour. It can also influence appraisal of stressful circumstances, which, in turn, influences coping skills which influence health behaviour.

The interactional stress model states that personality influences both appraisal and coping of stressful circumstances and this determines a physiological response to stress. The transactional stress moderation model states that there is a bidirectional association between personality, coping, appraisal and subsequent circumstances which all determine the physiological response to stress. The constitutional predisposition model states that a predisposition leads to physiological responsiveness which then influences both health and personality.

The illness behaviour model states that personality influences perception of and attention to normal physiological sensations (1), the labelling of such sensations (2), the reporting of symptoms (3) and the use of health care (4). This means that personality does not influence the actual disease.

Type D personality is associated with a risk of incident heart disease. It is also associated with an unhealthy lifestyle (1), genetic factors (2), ageing (3) and metabolic syndrome (4).

The metabolic syndrome is the clustering of four risk factors:

1. Being overweight
2. High triglycerides and low HDL cholesterol.
3. High blood pressure.
4. High fasting glucose levels.

Potential causes of the metabolic syndrome are an unhealthy lifestyle (1), genetic factors (2) and ageing (3). Type D personality influences all these factors. People with type-D personality exercise less often and have a less varied diet. The risk between type-D personality and cardiovascular disease may be mediated by metabolic syndrome. However, this is not fully supported by research.

There may be mediating biological mechanisms for the link between type D personality and risk for cardiovascular disease. One mediating biological mechanism may be the HPA axis. Hyper-activity refers to increased awakening response and increased levels of cortisol throughout the day. Hypoactivity refers to a decreased awakening response (i.e. cortisol). There is an association between type-D personality and cortisol levels and between type-D personality and the awakening response.

Hypercortisolemia refers to increased levels of cortisol in the blood. There are several consequences to this:

1. Increased metabolic rate
   This leads to higher glucose and increased oxidative stress. This can lead to vascular endothelial dysfunction and coronary artery calcification.
2. Inducing pro-inflammatory state
   This can lead to vascular endothelial dysfunction and coronary artery calcification.
3. Inhibition of vasodilation response to acetylcholine
   This leads to more constricted arteries and less flexible artery walls. This can lead to vascular endothelial dysfunction and coronary artery calcification.

Inflammation plays an important role in atherosclerosis. Inflammation is involved in the gradual accumulation of cholesterol, fat and calcium in the walls of the arteries. Blood clots from ruptured plaques may cause a heart attack. It is asymptomatic. Inflammation predicts long-term outcome in heart disease.

CRP is associated with dysfunction of endothelial cells (1), progression of atherosclerosis (2), expansion of infarction size (3) and damage in the coronary arteries (4). Type D personality is associated with increased inflammation. It partly mediates the association between type D personality and deterioration of physical health.

There is intrinsic heart rate control (i.e. without the influence of the brain). The brain influences the heart rate via the vagus nerve and the sympathetic cardiac nerves. The activation of the sympathetic nerves increases heart rate through the neurotransmitters adrenaline and noradrenaline. Activation of the vagus nerve (i.e. parasympathetic nerves) decreases heart rate through the neurotransmitter acetylcholine.

Altered cardiac autonomic activity, especially lower parasympathetic activity, is associated with the risk of developing coronary heart disease. Lower heart rate variability after myocardial infarction predicts cardiovascular events.

Type D personality is associated with an imbalance in cardiac autonomic regulation. There is higher sympathetic activity during rest, decreased parasympathetic control and a blunted stress response.

Oxidative stress refers to how your body manages damage (i.e. rusting process). It occurs when there is an excess of free oxidants, a decrease of antioxidants or both. It can lead to damage to the cell walls and DNA. It is involved in artery and heart muscle damage. An unhealthy lifestyle contributes to oxidative stress.

Type D personality is associated with chronically increased epinephrine (i.e. sympathetic activity) and cortisol. This leads to an autonomic imbalance (1), inflammation (2) and oxidative stress (3). This, in turn, leads to risk for cardiovascular disease.

Low socioeconomic status is associated with potentially stressful experiences. Adverse childhood events are associated with greater risk of CHD. Traditional gender roles renders the genders susceptible to different stressors (e.g. women are more susceptible to stressors in communion). Cultural differences may influence the relative importance of personality factors as determinants of health. Consideration of gender, age, culture and ethnicity has the potential to produce a more detailed account of associations between personality and health.