Personality has been of interest since ancient times. Hippocrates, also known as ‘The father of Western Medicine’ was possibly the first to document the association between personality and mental and physical health by describing the ancient medical theory of Humourism. Over the last 100 years the study of personality has been evolving and there are many different perspectives. Trait perspectives have become popular but they lack any underlying theory about how personality develops. Psychobiological models offer descriptions of personality and provide testable theories on how biology influences their development. A robust psychobiological model is Cloninger’s psychobiological theory and it provided the basis for this project.
This project explored the associations of personality in different mental health settings using the Temperament and Character Inventory (TCI; Cloninger, Przybeck, Svrakic, & Wetzel, 1994), the personality inventory developed by Cloninger and colleagues, that is suitable for measuring both normal and abnormal personality. The TCI was used to examine the impact of depression on personality measurement and personality associations to self-reported physical and mental health, mood disorders, hoarding behaviours and well-being.
Participants for this project were from three studies. Two randomised clinical trials designed to examine predictors of treatment response for depressed outpatients using either antidepressant medication (N=195) or psychotherapy (N=177) were used to examine the impact of depression on measures of personality. Data from the Canterbury Health, Ageing and Lifecourse (CHALICE) study (N=404), a random community sample of 50 year olds taking part in an observational study of ageing, were used to examine personality in relation to self-reported health, lifetime mood disorders, hoarding behaviours and well-being.
Harm avoidance and self-directedness were strongly associated with physical and mental health, mood disorders, hoarding behaviours and well-being. Both harm avoidance and self-directedness change with mood state. After adjusting for mood state, self-directedness but not harm avoidance was associated with risk of a lifetime mood disorder. High harm avoidance and low self-directedness were strongly associated with poorer self-reported mental and physical health and increased hoarding behaviours. Hoarding disorder was strongly associated with economic hardship and impairment of mental and physical functioning. For well-being, low harm avoidance and high self-directedness were associated with better well-being and these two variables explain more of the variance in well-being than other measures such as socio-demographics. The TCI personality variables of novelty seeking and self-transcendence were associated with specific psychopathology while reward dependence, persistence and cooperativeness had no or weak associations with different aspects of health and well-being.
TCI variables of harm avoidance and self-directedness were fundamental to health and well-being, consistent with the wider literature. The finding that self-directedness, but not harm avoidance, was a risk factor for mood disorder, could possibly be explained by self-directedness becoming increasingly important with age. Despite the overwhelming effect of harm avoidance and self-directedness, there were significant if subtle personality differences in the other TCI variables that contributed to health and well-being and personality assessment of the individual may be helpful in determining cognitive and emotional style. If the Cloninger model of personality, which separates the neurobiology of temperament and character, is correct then self-directedness should be more amenable to change and so is a potential target for interventions to reduce psychopathology.||