Borderline personality disorder

BORDERLINE PERSONALITY DISORDER is a chronic psychiatric disorder characterized by marked impulsivity, instability of mood and interpersonal relationships, and suicidal behaviour that can complicate medical care. Identifying this diagnosis is important for treatment planning. Although the cause of borderline personality disorder is uncertain, most patients improve with time. There is an evidence base for treatment using both psychotherapy and psychopharmacology. The clinical challenge centres on managing chronic suicidality.CaseColleen, a 22-year old student, is seen for a psychiatric assessment after presenting to the emergency department because of taking an overdose of acetaminophen pills. Although the immediate precipitant to her suicide attempt was a break-up with her boyfriend, she has a history of multiple suicide attempts since the age of 14. Colleen reports that she has daily mood swings, from depression to intense anger, and that she often cuts herself on the wrists and arms to relieve dysphoria. When stressed, she experiences feelings of unreality, sometimes hearing a voice telling her to kill herself. Colleen has had highly problematic relationships with men, falling quickly in and out of love and feeling that her life depends on them, even when they have behaved abusively toward her. What is the appropriate diagnosis and management of this patient?Personality disorders constitute a major group in the classification of mental disorders. According to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR),¹ these conditions are defined by maladaptive personality characteristics beginning early in life that have consistent and serious effects on functioning. Borderline personality disorder (BPD) is frequently seen in clinical practice.² Characterized by emotional turmoil and chronic suicidality (suicide ideation and attempts), this type of personality disorder presents some of the most difficult and troubling problems in all of psychiatry.     

Genital herpes and personality

Genital herpes, while having gained considerable attention as an important psychosexual disease, is not well understood. Precisely what factors trigger infectious reactivation is an important question that has yet to be answered. The present study investigated the relationship between recurrent genital herpes and personality. High and low recurrers were administered a demographic and disease history questionnaire and the Minnesota Multiphasic Personality Inventory (MMPI). Results revealed that, compared to low recurrers, the mean MMPI profile of high recurrers showed significantly greater elevations on nine of ten scales. The degree and pattern of elevation in the high profile is consistent with increased levels of autonomic arousal and stress. These findings are interpreted as suggestive of the possible role of personality in influencing the rate of infectious recurrence in genital herpes sufferers. The implications for psychologically based treatment strategies are discussed.     

Cardiac signatures of personality

Background

There are well-established relations between personality and the heart, as evidenced by associations between negative emotions on the one hand, and coronary heart disease or chronic heart failure on the other. However, there are substantial gaps in our knowledge about relations between the heart and personality in healthy individuals. Here, we investigated whether amplitude patterns of the electrocardiogram (ECG) correlate with neurotisicm, extraversion, agreeableness, warmth, positive emotion, and tender-mindedness as measured with the Neuroticism-Extraversion-Openness (NEO) personality inventory. Specifically, we investigated (a) whether a cardiac amplitude measure that was previously reported to be related to flattened affectivity (referred to as values) would explain variance of NEO scores, and (b) whether correlations can be found between NEO scores and amplitudes of the ECG.

Methodology/Principal Findings

NEO scores and rest ECGs were obtained from 425 healthy individuals. Neuroticism and positive emotion significantly differed between individuals with high and low values. In addition, stepwise cross-validated regressions indicated correlations between ECG amplitudes and (a) agreeableness, as well as (b) positive emotion.

Conclusions/Significance

These results are the first to demonstrate that ECG amplitude patterns provide information about the personality of an individual as measured with NEO personality scales and facets. These findings open new perspectives for a more efficient personality assessment using cardiac measures, as well as for more efficient risk-stratification and pre-clinical diagnosis of individuals at risk for cardiac, affective and psychosomatic disorders.     

The contribution of additive genetic variation to personality variation: heritability of personality

Individual animals frequently exhibit repeatable differences from other members of their population, differences now commonly referred to as ‘animal personality’. Personality differences can arise, for example, from differences in permanent environmental effects―including parental and epigenetic contributors―and the effect of additive genetic variation. Although several studies have evaluated the heritability of behaviour, less is known about general patterns of heritability and additive genetic variation in animal personality. As overall variation in behaviour includes both the among-individual differences that reflect different personalities and temporary environmental effects, it is possible for personality to be largely genetically influenced even when heritability of behaviour per se is quite low. The relative contribution of additive genetic variation to personality variation can be estimated whenever both repeatability and heritability are estimated for the same data. Using published estimates to address this issue, we found that approximately 52% of animal personality variation was attributable to additive genetic variation. Thus, while the heritability of behaviour is often moderate or low, the heritability of personality is much higher. Our results therefore (i) demonstrate that genetic differences are likely to be a major contributor to variation in animal personality and (ii) support the phenotypic gambit: that evolutionary inferences drawn from repeatability estimates may often be justified.     

Inhibitory ease--a personality type?

Measures of reactive, transmarginal and internal inhibition, inhibitory strength, extraversion (E) and neuroticism (N) were obtained from a sample of 25 Ss. A Principal Components analysis of the data disclosed factors which were identified tentatively as extinctive/reactive inhibition, transmarginal inhibition, and appetitive and aversive inhibitory strength. N loaded the transmarginal inhibition factor, and I(Introversion) the appetitive inhibitory strength factor. It is suggested that the role of E in appetitive CR extinction may be a function of the extent to which inhibitory strength is involved in inhibitory dynamism.     

Energy metabolism and animal personality

In this paper we show how animal personality could explain some of the large inter-individual variation in resting metabolic rate (MR) and explore methodological and functional linkages between personality and energetics. Personality will introduce variability in resting MR measures because individuals consistently differ in their stress response, exploration or activity levels, all of which influence MR measurements made with respirometry and the doubly-labelled water technique. Physiologists try to exclude these behavioural influences from resting MR measurements, but animal personality research indicates that these attempts are unlikely to be successful. For example, because reactive animals "freeze" when submitted to a stress, their MR could be classified as "resting" because of immobility when in fact they are highly stressed with an elevated MR. More importantly, recent research demonstrating that behavioural responses to novel and highly artificial stimuli are correlated with both behaviour and fitness under more natural circumstances calls into question the wisdom of excluding these behavioural influences on MR measurements. The reason that intra-specific variation in resting MR are so weakly correlated with daily energy expenditure (DEE) and fitness, may be that the latter two measures fully incorporate personality while the former partially excludes its influence. Because activity, exploration, boldness and aggressiveness are energetically costly, personality and metabolism should be correlated and physiological constraints may underlie behavioural syndromes. We show how physiological ecologists can better examine behavioural linkages between personality and metabolism, as required to better understand the physiological correlates of personality and the evolutionary consequences of metabolic variability.     

Sexual selection and animal personality

Consistent individual behavioural tendencies, termed “personalities”, have been identified in a wide range of animals. Functional explanations for personality have been proposed, but as yet, very little consideration has been given to a possible role for sexual selection in maintaining differences in personality and its stability within individuals. We provide an overview of the available literature on the role of personality traits in intrasexual competition and mate choice in both human and non‐human animals and integrate this into a framework for considering how sexual selection can generate and maintain personality. For this, we consider the evolution and maintenance of both main aspects of animal personality: inter‐individual variation and intra‐individual consistency.     

The genetics of human personality

Personality traits are the relatively enduring patterns of thoughts, feelings and behaviors that reflect the tendency to respond in certain ways under certain circumstances. Twin and family studies have showed that personality traits are moderately heritable, and can predict various lifetime outcomes, including psychopathology. The Research Domain Criteria characterizes psychiatric diseases as extremes of normal tendencies, including specific personality traits. This implies that heritable variation in personality traits, such as neuroticism, would share a common genetic basis with psychiatric diseases, such as major depressive disorder. Despite considerable efforts over the past several decades, the genetic variants that influence personality are only beginning to be identified. We review these recent and increasingly rapid developments, which focus on the assessment of personality via several commonly used personality questionnaires in healthy human subjects. Study designs covered include twin, linkage, candidate gene association studies, genome‐wide association studies and polygenic analyses. Findings from genetic studies of personality have furthered our understanding about the genetic etiology of personality, which, like neuropsychiatric diseases themselves, is highly polygenic. Polygenic analyses have showed genetic correlations between personality and psychopathology, confirming that genetic studies of personality can help to elucidate the etiology of several neuropsychiatric diseases.     

Social personality trait and fitness

Several recent studies have explored various aspects of animal personality and their ecological consequences. However, the processes responsible for the maintenance of personality variability within a population are still largely unknown. We have recently demonstrated that social personality traits exist in the common lizard (Lacerta vivipara) and that the variation in sociability provides an explanation for variable dispersal responses within a given species. However, we need to know the fitness consequences of variation in sociability across environmental contexts in order to better understand the maintenance of such variation. In order to achieve this, we investigated the relationship between sociability and survival, body growth and fecundity, in one-year-old individuals in semi-natural populations with varying density. 'Asocial' and 'social' lizards displayed different fitness outcomes in populations of different densities. Asocial lizards survived better in low-density populations, while social females reproduced better. Spatiotemporal variation in environmental conditions might thus be the process underlying the maintenance of these personality traits within a population. Finally, we also discuss the position of sociability in a more general individual behavioural pattern including boldness, exploration and aggressiveness.     

Dimensional models of personality disorder

There is little doubt that someday the classification of personality disorder will be dimensional. The failures of the categorical model are so many and are so well established that it is difficult to imagine that this model will ultimately survive. This paper provides a brief discussion of the major alternative proposals for a dimensional classification of personality disorder. It is possible that the authors of a future edition of a psychiatric diagnostic manual will simply choose one of these alternative proposals. However, the ideal solution might be to develop a common, integrative representation including the important contributions of each of the models.     

Evolutionary genomics of animal personality

Research on animal personality can be approached from both a phenotypic and a genetic perspective. While using a phenotypic approach one can measure present selection on personality traits and their combinations. However, this approach cannot reconstruct the historical trajectory that was taken by evolution. Therefore, it is essential for our understanding of the causes and consequences of personality diversity to link phenotypic variation in personality traits with polymorphisms in genomic regions that code for this trait variation. Identifying genes or genome regions that underlie personality traits will open exciting possibilities to study natural selection at the molecular level, gene-gene and gene-environment interactions, pleiotropic effects and how gene expression shapes personality phenotypes. In this paper, we will discuss how genome information revealed by already established approaches and some more recent techniques such as high-throughput sequencing of genomic regions in a large number of individuals can be used to infer micro-evolutionary processes, historical selection and finally the maintenance of personality trait variation. We will do this by reviewing recent advances in molecular genetics of animal personality, but will also use advanced human personality studies as case studies of how molecular information may be used in animal personality research in the near future.