AbstractBackgroundPersonality traits may influence development and adjustment to ongoing pain. Over the past 120 years, there has been considerable research into the relationship between pain and personality. This paper presents new evidence for common personality traits found amongst chronic pain sufferers. In particular, it evaluates evidence for Cloninger’s biopsychosocial model of personality in distinguishing typical personality features of chronic pain sufferers. It evaluates this evidence in the context of the past 120 years of research including psychodynamic formulations, MMPI studies, personality disorder investigations, and the influence of neuroticism on chronic pain.MethodsA literature search was conducted using PubMed, Medline, PsyclNFO, SCOPUS and Cochrane library. Search terms included chronic pain, pain, personality, neuroticism, harm avoidance, self-directedness, attachment, Temperament and Character Inventory (TCI-R), MMPI, MMPI-2, NEO-PI, EPI, Millon Clinical Multiaxial Inventory, Millon Behavioral Health Inventory, Millon Behavioral Medicine Diagnostic, the Personality Assessment Inventory, the Locus of Control Construct and different combinations of these terms.ConclusionsRecent descriptive studies using Cloninger’s Temperament and Character Inventory (TCI-R) suggest that higher harm avoidance and lower self-directedness may be the most distinguishing personality features of chronic pain sufferers. High harm avoidance refers to a tendency to be fearful, pessimistic, sensitive to criticism, and requiring high levels of re-assurance. Low self-directedness often manifests as difficulty with defining and setting meaningful goals, low motivation, and problems with adaptive coping. Evidence for this personality profile is found across a wide variety of chronic pain conditions including fibromyalgia, headache and migraine, temporomandibular disorder, trigeminal neuropathy, musculo-skeletal disorders and heterogeneous pain groups. Limitations are also discussed. For example, high harm avoidance is also found in those suffering anxiety and depression. While many studies control for such factors, some do not and thus future research should address such confounds carefully. The evidence is also evaluated within the context of past research into the existence of ‘a pain personality’. Psychodynamic formulations are found to be deficient in objective scientific methods. MMPI studies lack sufficient evidence to support ‘a pain personality’ and may be confounded by somatic items in the instrument. More recent neuroticism studies suggest a relationship between neuroticism and pain, particularly for adjustment to chronic pain. Personality disorders are more prevalent in chronic pain populations than non-pain samples.Clinical implicationsBecause harm avoidance reflects a tendency to developed conditioned fear responses, we suggest that higher harm avoidance may create more vulnerability to developing a fear-avoidance response to chronic pain. Furthermore, lower self-directedness may contribute to keeping a sufferer within this vicious cycle of fear, avoidance and suffering. Moreover, we suggest that harm avoidance and self-directedness are broader and more complex constructs than current clinical targets of CBT such as fear-avoidance and self-efficacy. Thus, assessing such personality traits may help to address the complexity of chronic pain presentations. For example, it may help to identify and treat sufferers more resistant to treatment, more prone to comorbidity and more vulnerable to entering the vicious cycle of chronic pain, suffering and disability.

A decrease in glutamate in the medial prefrontal cortex (mPFC) has been extensively found in animal models of chronic pain. Given that the mPFC is implicated in emotional appraisal, cognition and extinction of fear, could a potential decrease in glutamate be associated with increased pessimistic thinking, fear and worry symptoms commonly found in people with chronic pain? To clarify this question, 19 chronic pain subjects and 19 age- and gender-matched control subjects without pain underwent magnetic resonance spectroscopy. Both groups also completed the Temperament and Character, the Beck Depression and the State Anxiety Inventories to measure levels of harm avoidance, depression, and anxiety, respectively. People with chronic pain had significantly higher scores in harm avoidance, depression and anxiety compared to control subjects without pain. High levels of harm avoidance are characterized by excessive worry, pessimism, fear, doubt and fatigue. Individuals with chronic pain showed a significant decrease in mPFC glutamate levels compared to control subjects without pain. In people with chronic pain mPFC glutamate levels were significantly negatively correlated with harm avoidance scores. This means that the lower the concentration of glutamate in the mPFC, the greater the total scores of harm avoidance. High scores are associated with fearfulness, pessimism, and fatigue-proneness. We suggest that chronic pain, particularly the stress-induced release of glucocorticoids, induces changes in glutamate transmission in the mPFC, thereby influencing cognitive, and emotional processing. Thus, in people with chronic pain, regulation of fear, worry, negative thinking and fatigue is impaired.

This study provides evidence that ongoing family support is associated with substantial reductions in the adverse impact of substance abuse on consumers' patterns of service use, especially for consumers living in rural areas. If confirmed in other populations, study findings suggest that reinforcing services and support for family members who provide informal care helps to sustain involvement in care by the especially vulnerable population of individuals with a dual diagnosis of schizophrenia and substance abuse.

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