Personality endophenotypes for bipolar affective disorder: a family-based genetic association analysis

Affective Neuroscience Personality Scale (ANPS) and clinical implications: A systematic review

BACKGROUND

Affective neuroscience (AN) theory assumes the existence of seven basic emotional systems (i.e., SEEKING, ANGER, FEAR, CARE, LUST, SADNESS, PLAY) that are common to all mammals and evolutionarily determined to be tools for survival and, in general, for fitness. Based on the AN approach, the Affective Neuroscience Personality Scales (ANPS) questionnaire was developed to examine individual differences in the defined basic emotional systems. The current systematic review aims to examine the use of ANPS in clinical contexts attempting to define those behavioral elements associated with underlying stable personality traits.

METHODS

The systematic review was conducted following the PRISMA statements. PubMed and PsycInfo were used for research literature from March 2003 to November 2021.

RESULTS

Forty-four studies including ANPS were identified from 1763 studies reviewed. Sixteen studies met the inclusion criteria.

LIMITATIONS

The review comprised some papers with incomplete psychological assessments (e.g., lack of other measures in addition to the ANPS) and missing information (e.g., on the [sub]samples), which may affect the generalizability of findings.

CONCLUSION

Specific endophenotypes and/or patterns of emotional/motivational systems were found for several mental disorders. Specifically, endophenotypes emerged for the Depressive and Autism Spectrum Disorders, Borderline and Avoidant Personality Disorders, type I and II Bipolar Disorders, and the Obsessive-Compulsive Disorder. The endophenotypes can provide useful reflective elements for both psychodiagnosis and intervention. Overall, the current study may represent an attempt to contribute to the understanding of the basic emotional systems involved in the psychopathological manifestations identified by AN.

A comprehensive review of studies using the Affective Neuroscience Personality Scales in the psychological and psychiatric sciences

Jaak Panksepp's Affective Neuroscience Theory (ANT) belongs to the most prominent emotion theories in the psychological and psychiatric sciences. ANT proposes the existence of seven primary emotional systems deeply anchored in the mammalian brain. These emotional/motivational systems have been shaped by evolutionary processes and function as tools for survival in mammalian species. The systems are called SEEKING, LUST, CARE, and PLAY, as well as ANGER, FEAR, and SADNESS. Panksepp carved out these emotional systems via means of deep brain stimulation, brain lesion and pharmacological manipulation studies. Davis et al. (2003) designed the Affective Neuroscience Personality Scales (ANPS) against the background of findings from ANT. This self-report inventory is meant to enable researchers to assess individual differences in primary emotional systems. Seventeen years have passed since the first version of the ANPS has been published. Therefore, we now provide a comprehensive overview on studies using the ANPS including work from personality science, psychiatry and the neurosciences.

The Association Between Affective Temperament Traits and Dopamine Genes in Obese Population

Studies indicate the heritable nature of affective temperament, which shows personality traits predisposing to the development of mental disorders. Dopaminergic gene polymorphisms such as DRD4, COMTVal158Met, and DAT1 have been linked to affective disorders in obesity. Due to possible correlation between the aforementioned polymorphisms and the affective temperament, the aim of our research was to investigate this connection in an obese population. The study enrolled 245 obese patients (178 females; 67 males). The affective temperament was assessed using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego autoquestionnaire (TEMPS-A). Genetic polymorphisms of DAT1, COMTVal158Met and DRD4 were collected from peripheral blood sample and determined using a polymerase chain reaction (PCR). Only in COMT polymorphisms, the cyclothymic and irritable dimensions were significantly associated with Met/Val carriers (p = 0.04; p = 0.01). Another interesting finding was the correlation between the affective temperament and age in men and women. We assume that dopamine transmission in heterozygotes of COMT may determine the role of the affective temperament in obese persons. Dopaminergic transmission modulated by COMT may be responsible for a greater temperament expression in obese individuals. To our knowledge, this is the first study describing the role of affective temperament in the obese population, but more research is needed in this regard.

Affective temperaments during pregnancy and postpartum period: a click to hyperthymic temperament

BACKGROUND

Pregnancy and postpartum periods are the main reproductive periods during which women experience mood disorders. Affective temperaments are known antecedents of mood disorders and their importance is increasing in time for early diagnosis and determining risky groups. But data about affective temperaments during perinatal period is limited.

METHODS

Women during pregnancy and perinatal period and healthy controls who are not in perinatal period are included in the study. 83 pregnant women in 1st trimester, 94 pregnant women in 2nd trimester and 115 pregnant women in 3rd trimester; 32 women in 1st month postpartum and 89 women in 2nd month postpartum; and 88 healthy non-pregnant women with similar ages were evaluated regarding their temperament evaluation of Memphis, Pisa, Paris and San Diego auto-questionnaire (TEMPS-A) scores.

RESULTS

Women in perinatal period had higher scores of hyperthymic temperaments than the control group. Women in the 2nd month of postpartum period had also higher anxious temperament scores. And women in the second trimester had the highest hyperthymic temperament scores.

CONCLUSION

Pregnancy and postpartum periods correlate with hyperthymic temperament characteristics in women without active psychiatric diagnosis. Future studies will help to understand if this is a mental quietness or increased risk for bipolarity.

Identifying affective personality profiles: A latent profile analysis of the Affective Neuroscience Personality Scales

Based on evolutionary theory, a recent model in affective neuroscience delineated six emotional brain systems at the core of human personality: SEEKING, CARING, PLAYFULNESS, FEAR, ANGER, SADNESS. The Affective Neuroscience Personality Scales (ANPS) assess their functioning. Using a person-centred approach of the ANPS, this study: (i) examined the existence of latent personality profiles, (ii) studied their gender invariance, (iii) assessed their longitudinal (4 years) stability, and (iv) explored how they relate to several intrapersonal, interpersonal, and emotion regulation skills. Latent Profile Analysis in 2 samples (Canadian, longitudinal, N = 520; French, cross-sectional, N = 830) found that, qualitatively, 3 profiles characterized both populations and genders, with one distinction for the second profile where the French women endorsed slightly higher and lower scores for, respectively, the negative and positive emotions. Whilst not being quantitatively similar across genders, the personality profiles remained consistent across time in the longitudinal sample. Associations between profiles and intrapersonal (e.g. depression), interpersonal (e.g. empathy), and emotion regulation skills measures (e.g. emotional intelligence) offered concurrent validity evidence. This person centred approach to ANPS offers a holistic and parsimonious way to study affective personality dimensions. It opens promising avenues for future studies on the predictive value of ANPS profiles, and for personality-targeted interventions.

Personality traits as an endophenotype in genetic studies on suicidality in bipolar disorder

Introduction The influence of personality traits on suicidal behaviour risk has been well documented. Personality traits and suicidal behaviour are partially genetically determined and personality has been described as an endophenotype of suicidal behaviour. The aim of this study was to investigate a possible association between personality traits with suicidal behaviour and selected serotonergic gene polymorphisms.

METHODS

In the study we included 156 patients meeting DSM-IV criteria for bipolar disorder (BP) and 93 healthy controls. The personality dimensions were assessed using the Temperament and Character Inventory (TCI). We genotyped two selected polymorphisms of the tryptophan hydroxylase 1 (TPH1) gene (rs1800532 218A>C and rs1799913 779A>C) and polymorphism in the promoter region of serotonin transporter gene (5-HTTLPR, rs25531) related to serotoninergic neurotransmission. Multiple poisson regression, logistic regression and Kruskal-Wallis tests were applied.

RESULTS

We found numerous differences between the BP patients and the control group in terms of their TCI dimensions/subdimensions. Significant differences were found between patients with, and without, suicidal attempts in fatigability and asthenia (Ha4), as well as in harm avoidance (Ha). We also found that the interactions between TCI subdimensions (the interaction of disordiness (Ns4) and spiritual acceptance (St3), disordiness (Ns4) and integrated conscience (C5), extravagance (Ns3) and resourcefulness (Sd3)) were significantly contributing for suicidal behaviour risk. We found association between all studied genetic polymorphisms and several TCI dimensions and subdimensions.

CONCLUSION

Our results confirm that personality traits are partially determined by genes. Both personality traits and the interactions between temperament and character traits, may be helpful in predicting suicidal behaviour.

Factor analysis of temperament and personality traits in bipolar patients: Correlates with comorbidity and disorder severity

BACKGROUND

Temperament and personality traits have been suggested as endophenotypes for bipolar disorder based on several lines of evidence, including heritability. Previous work suggested an anxious-reactive factor identified across temperament and personality inventories that produced significant group discrimination and could potentially be useful in genetic analyses. We have attempted to further characterize this factor structure in a sample of bipolar patients.

METHODS

A sample of 1195 subjects with bipolar I disorder was evaluated, all with complete data available. Dimension reduction across two inventories identified 18 factors explaining 39% of the variance.

RESULTS

The two largest factors reflected affective instability and general anxiety/worry, respectively. Subsequent analyses of the clinical features associated with bipolar disorder revealed specificity for the factors in a predictable pattern. Cluster analysis of the factors identified a subgroup defined by a strong lack of general anxiety and low affective instability represented by the first two factors. The remaining subjects could be distinguished into two clusters by the presence of either more positive characteristics, including persistence/drive, spirituality, expressivity, and humor, or more negative characteristics of depression and anxiety.

LIMITATIONS

These analyses involved bipolar I subjects only and must be extended to other bipolar spectrum diagnoses, unaffected relatives, and individuals at risk.

CONCLUSIONS

These results suggest that temperament and personality measures access latent traits associated with important clinical features of bipolar disorder. By translating clinical variables into quantitative traits, we may identify subgroups of bipolar patients with distinct clinical profiles, thereby facilitating both individual treatment strategies and genetic analyses.

Longitudinal and Sex Measurement Invariance of the Affective Neuroscience Personality Scales

The Affective Neuroscience Personality Scales (ANPS) is a personality instrument based on six evolutionary-related brain systems that are at the foundation of human emotions and behaviors: SEEKING, CARING, PLAYFULNESS, FEAR, ANGER, and SADNESS. We sought to assess for the short and long versions of the ANPS: (a) the longitudinal measurement invariance and long-term (4-year) stability and (b) the sex measurement invariance. Using data from a Canadian cohort ( N = 518), we used single-group confirmatory factor analysis to assess longitudinal invariance and multiple-group confirmatory factor analysis to assess sex invariance, according to a five-step approach evaluating five invariance levels (configural, metric, scalar, residual, and complete). Results supported full longitudinal invariance for both versions for all invariance levels. Partial residual invariance was supported for sex invariance. The long-term stability of both versions was good to excellent. Implications for personality assessment and ANPS development are discussed.

Confirmatory test of two factors and four subtypes of bipolar disorder based on lifetime psychiatric co-morbidity

BACKGROUND

The first aim was to use confirmatory factor analysis (CFA) to test a hypothesis that two factors (internalizing and externalizing) account for lifetime co-morbid DSM-IV diagnoses among adults with bipolar I (BPI) disorder. The second aim was to use confirmatory latent class analysis (CLCA) to test the hypothesis that four clinical subtypes are detectible: pure BPI; BPI plus internalizing disorders only; BPI plus externalizing disorders only; and BPI plus internalizing and externalizing disorders.

METHOD

A cohort of 699 multiplex BPI families was studied, ascertained and assessed (1998-2003) by the National Institute of Mental Health Genetics Initiative Bipolar Consortium: 1156 with BPI disorder (504 adult probands; 594 first-degree relatives; and 58 more distant relatives) and 563 first-degree relatives without BPI. Best-estimate consensus DSM-IV diagnoses were based on structured interviews, family history and medical records. MPLUS software was used for CFA and CLCA.

RESULTS

The two-factor CFA model fit the data very well, and could not be improved by adding or removing paths. The four-class CLCA model fit better than exploratory LCA models or post-hoc-modified CLCA models. The two factors and four classes were associated with distinctive clinical course and severity variables, adjusted for proband gender. Co-morbidity, especially more than one internalizing and/or externalizing disorder, was associated with a more severe and complicated course of illness. The four classes demonstrated significant familial aggregation, adjusted for gender and age of relatives.

CONCLUSIONS

The BPI two-factor and four-cluster hypotheses demonstrated substantial confirmatory support. These models may be useful for subtyping BPI disorders, predicting course of illness and refining the phenotype in genetic studies.

Dopamine transporter gene may be associated with bipolar disorder and its personality traits

Dopamine transporter and its genetic factors have been suggested to play a critical role in the development of bipolar disorder (BPD). However, the importance of the dopamine transporter gene (DAT1) in the pathogenesis of BPD remains unclear. The aims of this study were to assess 18 polymorphisms of the DAT1 gene to determine whether this gene is associated with BPD and whether it influences personality traits of patients with BPD. DAT1 polymorphisms were analyzed in 492 BPD (374 BPDI and 118 BPDII) patients and 436 controls. All participants were screened using the same assessment tool, and all met the criteria for BPD. The Tridimensional Personality Questionnaire was used to assess personality traits in both patients and controls. Several polymorphisms had a weak association with BPD, including rs2550948, rs2652511, and rs2975226 in allele distribution analysis (P < 0.05). Furthermore, the promoter G-A-C-G haplotype (rs6350-rs2975226-rs2652511-rs6413429) was over-represented in the BPD patients compared to the controls (P = 0.007). In personality assessment, the BPDII patients had the highest harm avoidance score, followed by the BPDI patients and controls (P = 3.7 × 10(-32)). In addition, a significant association between rs40184 and harm avoidance was found in the patients with BPD. The DAT1 promoter may be associated with vulnerabilities in BPD. The BPD patients had a higher rate of harm avoidance personality traits than the controls, and DAT1 variants may influence personality traits in patients with BPD.

Factors associated with lithium efficacy in bipolar disorder

About one-third of lithium-treated, bipolar patients are excellent lithium responders; that is, lithium monotherapy totally prevents further episodes of bipolar disorder for ten years and more. These patients are clinically characterized by an episodic clinical course with complete remission, a bipolar family history, low psychiatric comorbidity, mania-depression episode sequences, a moderate number of episodes, and a low number of hospitalizations in the pre-lithium period. Recently, it has been found that temperamental features of hypomania (a hyperthymic temperament) and a lack of cognitive disorganization predict the best results of lithium prophylaxis. Lithium exerts a neuroprotective effect, in which increased expression of brain-derived neurotrophic factor (BDNF) and inhibition of the glycogen synthase kinase-3 (GSK-3) play an important role. The response to lithium has been connected with the genotype of the BDNF gene and serum BDNF levels. A better response to lithium is connected with the Met allele of the BDNF Val/Met polymorphism, as is a hyperthymic temperament. Excellent lithium responders have normal cognitive functions and serum BDNF levels, even after long-term duration of the illness. The preservation of cognitive functions in long-term lithium-treated patients may be connected with the stimulation of the BDNF system, with the resulting prevention of affective episodes exerting deleterious cognitive effects, and possibly also with lithium's antiviral effects. A number of candidate genes that are related to neurotransmitters, intracellular signaling, neuroprotection, circadian rhythms, and other pathogenic mechanisms of bipolar disorder were found to be associated with the lithium prophylactic response. The Consortium on Lithium Genetics (ConLiGen) has recently performed the first genome-wide association study on the lithium response in bipolar disorder.

Permutation Tests in the Educational and Behavioral Sciences

Over the past two decades, permutation tests (PTs) have received much attention in the educational and behavioral sciences. The aim of this article is to review the theoretical developments of PTs, the active areas in the educational and behavioral research using PTs, and the types of analysis under which PTs have been applied. We obtained 224 published articles, which included 141 theoretical articles and 83 application articles. After scrutinizing each article, we are happy to see that (1) some researchers began to advocate introducing PTs into basic statistics training; (2) computing load for PTs may be reduced dramatically by some intelligent algorithms; (3) PTs began to be applied in new areas such as studies on the relationship between brain and behavior and the relationship between gene and behavior; (4) besides simple types of analysis such as independent two-group comparison, PTs can also be carried out under more complex situations such as multivariate analysis. However, we should also notice that PTs are still mostly used for simple analyses (e.g., randomness analysis).

Psychiatrists' views of the genetic bases of mental disorders and behavioral traits and their use of genetic tests

We examined how 372 psychiatrists view genetic aspects of mental disorders and behaviors and use genetic tests (GTs). Most thought that the genetic contribution was moderate/high for bipolar disorder, schizophrenia, depression, Alzheimer's, intelligence, creativity, anxiety, and suicidality. In the past 6 months, 14.1% ordered GTs, 18.3% discussed prenatal testing with patients, 36.0% initiated discussions about other GTs, 41.6% had patients ask about GTs, and 5.3% excluded GT results from patient records. Many thought that GTs; were available for schizophrenia (24.3%) and major depression (19.6%). Women were more likely to report that patients asked about GTs; and were less certain about the degree of genetic contribution to several disorders. Psychiatrists perceive strong genetic bases for numerous disorders and traits, and many have discussed and ordered tests for GTs, but have relatively limited knowledge about available tests. These data suggest possible sex differences in psychiatrists' beliefs about genetic contributions to disorders and have implications for future research, education, policy, and care.

Response to lithium in bipolar disorder: clinical and genetic findings

The use of lithium is a cornerstone for preventing recurrences in bipolar disorder (BD). The response of patients with bipolar disorder to lithium has different levels of magnitude. About one-third of lithium-treated patients are excellent lithium responders (ELR), showing total prevention of the episodes. A number of clinical characteristics were delineated in patients with favorable response to lithium as regards to clinical course, family history of mood disorders, and psychiatric comorbidity. We have also demonstrated that temperamental features of hypomania (a hyperthymic temperament) and a lack of cognitive disorganization predict the best results of lithium prophylaxis. A degree of prevention against manic and depressive episodes has been regarded as an endophenotype for pharmacogenetic studies. The majority of data have been gathered from so-called "candidate" gene studies. The candidates were selected on the basis of neurobiology of bipolar disorder and mechanisms of lithium action including, among others, neurotransmission, intracellular signaling, neuroprotection or circadian rhythms. We demonstrated that response to lithium has been connected with the genotype of BDNF gene and serum BDNF levels and have shown that ELR have normal cognitive functions and serum BDNF levels, even after long-term duration of the illness. A number of genome-wide association studies (GWAS) of BD have been also performed in recent years, some of which also focused on lithium response. The Consortium on Lithium Genetics (ConLiGen) has established the large sample for performing the genome-wide association study (GWAS) of lithium response in BD, and the first results have already been published.

Polymorphism of circadian clock genes and temperamental dimensions of the TEMPS-A in bipolar disorder

BACKGROUND

Previously, we found correlations between lithium efficacy in bipolar disorder and temperamental dimensions of the TEMPS-A and also genes involved in the regulation of biological rhythms ("clock" genes). Here, were attempted to investigate an association between multiple, single nucleotide polymorphisms (SNPs) of four clock genes (CLOCK, ARNTL, TIM, PER3) and temperamental dimensions of the TEMPS-A, in bipolar patients.

METHODS

The study included 70 patients with bipolar disorder (20 males, 50 females), with a mean age of 59±12 years. The TEMPS-A questionnaire, 110 questions version, was used assessing five temperament domains: depressive, cyclothymic, hyperthymic, irritable and anxious. Genotyping was done for 9 SNPs of the CLOCK gene, 18 SNPs of the ARNTL gene, 6 SNPs of the TIM gene and 5 SNPs of the PER3 gene.

RESULTS

An association with hyperthymic temperament was found for three, and with anxious temperament for four SNPs of the ARTL gene. An association of cyclothymic temperament was found with two SNPs of the TIM gene and of depressive temperament with one SNP of the PER3 gene. No association was observed with SNPs of the CLOCK gene.

LIMITATIONS

Relatively small number of patients studied and insufficient correction for multiple testing.

CONCLUSIONS

These results may suggest that the ARNTL, TIM and PER3 genes may be associated with temperamental dimensions measured by the TEMPS-A, each of this gene being specific to given temperamental dimension. Of special interest may be the polymorphisms of ARNTL gene also connected with predisposition to bipolar mood disorder and/or lithium response.

The Brain Derived Neurotrophic Factor and Personality

The study of the biological basis of personality is a timely research endeavor, with the aim of deepening our understanding of human nature. In recent years, a growing body of research has investigated the role of the brain derived neurotrophic factor (BDNF) in the context of individual differences across human beings, with a focus on personality traits. A large number of different approaches have been chosen to illuminate the role of BDNF for personality, ranging from the measurement of BDNF in the serum/plasma to molecular genetics to (genetic) brain imaging. The present review provides the reader with an overview of the current state of affairs in the context of BDNF and personality.

Genes in the serotonin pathway are associated with bipolar affective disorder in a Han Chinese population

Serotonin plays an important role in mood regulation, but the involvement of serotonin pathway genes in the development of bipolar I disorder (BP-I), a mood disorder, is not clear. We selected 21 single-nucleotide polymorphisms (SNPs) within the HTR2A gene, 8 within the SLC6A4 gene and 23 within the TPH2 gene for genotyping using the GoldenGate genotyping assay. A total of 375 patients with BP-I and 475 normal controls were recruited. Two out of 21 SNPs (rs1475196 and rs9567747) in the HTR2A gene and 1/23 SNPs (rs17110566) in the TPH2 gene were significantly associated with BP-I, both genotype-wise and allele-wise. Furthermore, a specific haplotype in the HTR2A gene showed a significant association with BP-I. Our results indicate that the HTR2A and TPH2 genes in the serotonin pathway play important roles in susceptibility to BP-I.

Exploring personality features in patients with affective disorders and history of suicide attempts: a comparative study with their parents and control subjects

Personality traits are important candidate predictors of suicidal behavior. Several studies have reported an association between personality/temperament traits and suicidal behavior, suggesting personality traits as intermediary phenotypes related to suicidal behavior. Thus, it is possible that suicide attempts can be accounted for by increased familial rates of risk personality traits. The aim of this work was to evaluate personality traits in affective disorder patients with attempted suicide and to compare them with the personality trait scores of their parents. In addition, ITC scores in the two groups were compared with a healthy control sample. The patients evaluated met the DSM-IV criteria for major depression disorder or dysthymia and had a documented history of suicide attempts. Psychiatric diagnoses of patients and parents were done according to the SCID-I and the personality was assessed using the Temperament and Character Inventory. We analyzed 49 suicide attempt subjects and their parents (n = 95) and 89 control subjects. We observed that temperament and character dimensions were similar between patients and their parents (P > 0.05). In particular, we observed that high HA and low P, SD, and CO were shared among families. Our study is the first to report that the personality traits of affective disorder patients with a history of attempted suicide are shared between patients and their parents.

Heritability and linkage analysis of personality in bipolar disorder

BACKGROUND

The many attempts that have been made to identify genes for bipolar disorder (BD) have met with limited success, which may reflect an inadequacy of diagnosis as an informative and biologically relevant phenotype for genetic studies. Here we have explored aspects of personality as quantitative phenotypes for bipolar disorder through the use of the Temperament and Character Inventory (TCI), which assesses personality in seven dimensions. Four temperament dimensions are assessed: novelty seeking (NS), harm avoidance (HA), reward dependence (RD), and persistence (PS). Three character dimensions are also included: self-directedness (SD), cooperativeness (CO), and self-transcendence (ST).

METHODS

We compared personality scores between diagnostic groups and assessed heritability in a sample of 101 families collected for genetic studies of BD. A genome-wide SNP linkage analysis was then performed in the subset of 51 families for which genetic data was available.

RESULTS

Significant group differences were observed between BD subjects, their first-degree relatives, and independent controls for all but RD and PS, and all but HA and RD were found to be significantly heritable in this sample. Linkage analysis of the heritable dimensions produced several suggestive linkage peaks for NS (chromosomes 7q21 and 10p15), PS (chromosomes 6q16, 12p13, and 19p13), and SD (chromosomes 4q35, 8q24, and 18q12).

LIMITATIONS

The relatively small size of our linkage sample likely limited our ability to reach genome-wide significance in this study.

CONCLUSIONS

While not genome-wide significant, these results suggest that aspects of personality may prove useful in the identification of genes underlying BD susceptibility.

BDNF Val66Met polymorphism and lithium response: a meta-analysis

AIM

To characterize the impact of the Val66Met polymorphism on lithium response in patients with bipolar disorder.

METHODS

A systematic literature search of MEDLINE, Web of Science, PsychINFO and Cochrane CENTRAL was conducted from the earliest possible date through to 1 July 2012. The search was performed using the following medical subject headings: bipolar disorder, lithium, lithium carbonate, pharmacogenomics, pharmacogenetics, polymorphism and brain-derived neurotrophic factor. Five of 71 identified studies met the inclusion criteria. Data were abstracted using a standardized data abstraction tool. For categorical end points, the pooled odds ratio with 95% CI was calculated. Random effects models were used for analysis.

RESULTS

The Val66Met polymorphism did not predict response to prophylactic lithium in this combined population (odds ratio: 2.67; p = 0.078).

CONCLUSION

This analysis suggests that the Val66Met polymorphism does not predict response to lithium treatment in bipolar disorder in this combined population. Prospective studies are needed to clearly define the role of Val66Met polymorphism of BDNF in lithium response.

Heritability and genome-wide SNP linkage analysis of temperament in bipolar disorder

BACKGROUND

The many attempts to identify genes for bipolar disorder (BD) have met with limited success, which has generally been attributed to genetic heterogeneity and small gene effects. However, it is also possible that the categorical phenotypes used in genetic studies of BD are not the most informative or biologically relevant. We have explored aspects of temperament as quantitative phenotypes for BD through the use of the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Auto-questionnaire (TEMPS-A), which is designed to assess lifelong, milder aspects of bipolar symptomatology and defines five temperaments: hyperthymic, dysthymic, cyclothymic, irritable, and anxious.

METHODS

We compared temperament scores between diagnostic groups and assessed heritability in a sample of 101 families collected for genetic studies of BD. A genome-wide SNP linkage study was then performed in the subset of 51 families for which genetic data was available.

RESULTS

Significant group differences were observed between BD subjects, their first-degree relatives, and independent controls, and all five temperaments were found to be significantly heritable, with heritabilities ranging from 21% for the hyperthymic to 52% for the irritable temperaments. Suggestive evidence for linkage was observed for the hyperthymic (chromosomes 1q44, 2p16, 6q16, and 14q23), dysthymic (chromosomes 3p21 and 13q34), and irritable (chromosome 6q24) temperaments.

LIMITATIONS

The relatively small size of our linkage sample likely limited our ability to reach genome-wide significance in this study.

CONCLUSIONS

While not genome-wide significant, these results suggest that aspects of temperament may prove useful in the identification of genes underlying BD susceptibility.

The dopamine transporter gene possibly affects personality traits in patients with early-onset major depressive disorder

OBJECTIVE

Comorbid personality pathologies may affect the outcome of patients with major depression (MD). The dopamine transporter gene DAT1 (SLC6A3) has been suggested to play a role in both depression and specific personality traits. The aim of this study was to assess five polymorphisms of the DAT1 gene (rs2550948, rs2975226, rs6347, rs27072, and 3'-VNTR) to determine whether this gene influences personality traits in patients with MD or its subgroups.

METHODS

The DAT1 polymorphisms were analysed in 463 unrelated Han Chinese MD patients. The personality traits, novelty seeking (NS), and harm avoidance (HA), were examined using the Tridimensional Personality Questionnaire. The patients were also divided into four clinical subgroups on the basis of differences in their sex (male or female) and age at disease onset (early or late).

RESULTS

There was no association between the DAT1 gene and either NS or HA in the total MD sample or in the sex-based subgroups. However, early-onset MD patients with the G/G genotype of rs2550948 and the T/T genotype of rs2975226 had lower NS scores than did patients with the other genotypes (p corrected = 0.05 for rs2550948 and p corrected = 0.005 for rs2975226).

CONCLUSION

Our study suggests that DAT1 promoter variants possibly influence specific personality traits in the early-onset subgroup of depressed patients in the Han Chinese population. Further prospective cohort studies are required to verify our preliminary finding and to confirm the effects of personality susceptibility on long-term disease outcomes.

Suicide attempts and psychological risk factors in patients with bipolar and unipolar affective disorder

Suicide is an important clinical problem in psychiatric patients. The highest risk of suicide attempts is noted in affective disorders. The aim of the study was looking for suicide risk factors among personality dimensions and value system in patients with diagnosis of unipolar and bipolar affective disorder (n=189 patients, n=101 controls). To establish the diagnosis, we used SCID (Structured clinical interview for diagnostic and statistical manual of mental disorders, fourth edition) questionnaire, TCI (Temperament and Character Inventory) questionnaire and Value Survey--to assess the personality. The main limitations of the study are number of participants, lack of data about stressful life events and treatment with lithium. Novelty seeking and harm avoidance dimensions constituted suicide attempt risk factors in the group of patients with affective disorders. Protective role of cooperativeness was discovered. Patients with and without suicide attempt in lifetime history varied in self-esteem position in Value Survey.

The influence of the Val158Met catechol-O-methyltransferase polymorphism on the personality traits of bipolar patients

Introduction

Certain personality traits and genetic polymorphisms are contributing factors to bipolar disorder and its symptomatology, and in turn, this syndrome influences personality. The aim of the present study is to compare the personality traits of euthymic bipolar patients with healthy controls and to investigate the effect of the catechol-O-methyltransferase (COMT) Val158Met genotype on those traits. We recruited thirty seven bipolar I patients in euthymic state following a manic episode and thirty healthy controls and evaluated their personality by means of the Cloninger’s Temperament and Character Inventory (version TCI-R-140). We assessed the influence of the polymorphism Val158Met in the COMT gene on the personality of these patients. The patients scored higher than controls in harm avoidance (61.3±12.5 vs. 55.3±8.1) and self-transcendence (45.3±12.8 vs. 32.7±8.2) and scored lower than controls in self-directedness (68.8±13.3 vs. 79.3±8.1), cooperativeness (77.1±9.1 vs. 83.9±6.5) and persistence (60.4±15.1 vs. 67.1±8.9). The novelty seeking dimension associates with the Val158Met COMT genotype; patients with the low catabolic activity genotype, Met/Met, show a higher score than those with the high catabolic activity genotype, Val/Val.

Conclusions

Suffering from bipolar disorder could have an impact on personality. A greater value in harm avoidance may be a genetic marker for a vulnerability to the development of a psychiatric disorder, but not bipolar disorder particularly, while a low value in persistence may characterize affective disorders or a subgroup of bipolar patients. The association between novelty seeking scores and COMT genotype may be linked with the role dopamine plays in the brain’s reward circuits.

Bipolar spectrum: Relevant psychological and biological factors

The bipolar spectrum is a concept which bridges bipolar I disorder and unipolar depression. As Kraepelin described, there may be continuity across mood disorders. If this is the case, why should we discriminate for drug choice For example, it is generally accepted that mood stabilizers should be used for the bipolar spectrum, whereas antidepressants are for unipolar depression. If these disorders are diagnostically continuous, it is possible that the same drug could be effective in treating both bipolar I disorder/spectrum and unipolar depression. To resolve this question, I would like to propose my hypothesis that there is an inflexion point which constitutes the boundary between the bipolar spectrum and unipolar depression. It is likely that this inflexion point consists of temperaments as, reportedly, there are many significant differences in the presence of various temperaments between the bipolar spectrum (bipolar II, II1/2 and IV) and unipolar depression. These findings suggest that temperaments could draw a boundary between the bipolar spectrum and unipolar depression. Moreover, it has been shown that certain temperaments may be associated with several biological factors and may be associated with drug response. As such, whilst the concept of the bipolar spectrum emphasizes continuity, it is the proposed inflexion point that discriminates drug responses between the bipolar spectrum and unipolar depression. At the moment, although hypothetical, I consider this idea worthy of further research.

Towards a multifactorial approach for prediction of bipolar disorder in at risk populations

BACKGROUND

The high prevalence, recurrence rate, chronicity, and illness burden in bipolar disorder (BD) are well documented. Moreover, insufficient response with conventional pharmacological and manual-based psychosocial interventions, as well as evidence of illness progression and acceleration, invite the need for early detection and primary prevention.

METHODS

Herein we comprehensively review extant studies reporting on a bipolar prodrome. The overarching aim is to propose a predictive algorithm (i.e. prediction of BD in at-risk populations) integrating genetic (i.e. family history), environmental (e.g. childhood maltreatment) and biological markers (i.e. BDNF, inflammatory and oxidative stress markers). Computerized databases i.e. Pubmed, PsychInfo, Cochrane Library and Scielo were searched using the followed terms: bipolar disorder cross-referenced with prodromal, preclinical, at risk mental states, clinical high risk, ultra high risk, biomarkers, brain-derived neurotrophic factor, inflammation, cytokines, oxidative stress, prediction and predictive model.

RESULTS

Available evidence indicates that a prodrome to bipolar disorder exists. Commonly encountered features preceding the onset of a manic episode are affective lability, irritability, anger, depression, anxiety, substance use disorders, sleep disorders, as well as disturbances in attention and cognition. Non-specificity and insufficient sensitivity have hampered the development of an adequate prediction algorithm.

LIMITATIONS

Limitations include biases associated with retrospective studies, poor characterization of clinical high risk, inadequacy of prospective studies regarding sample selection and absence of specificity of risk states.

CONCLUSION

We propose a hypothetical prediction algorithm that is combinatorial in approach that attempts to integrate family history, early adversity, and selected biomarkers.

Genome-wide association study of temperament in bipolar disorder reveals significant associations with three novel Loci

BACKGROUND

The many attempts to identify genes for bipolar disorder (BD) have met with limited success, which has generally been attributed to genetic heterogeneity and small gene effects. However, it is also possible that the categorical phenotypes used in genetic studies of BD are not the most informative or biologically relevant. Although quantitative phenotypes provide an alternative to categorical phenotypes based on diagnosis, they have not been fully exploited in BD genetics due to the lack of accessible biological measures. We have explored aspects of temperament as quantitative phenotypes that might define subtypes of BD with different clinical features and courses of illness. Temperament is a heritable personality factor that establishes the baseline level of reactivity, mood, and energy of a person.

METHODS

We have performed a genome-wide association study with genotype data from the Bipolar Genome Study and 1263 bipolar subjects that had completed the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A). The TEMPS-A is designed to assess lifelong, milder aspects of bipolar symptomatology and defines five temperaments: hyperthymic, dysthymic, cyclothymic, irritable, and anxious.

RESULTS

The irritable temperament produced the most significant result with a genome-wide significant p value of 1.7 × 10(-8) on chromosome 1. The hyperthymic temperament produced additional genome-wide significant p values of 4.1 × 10(-8) and 2.1 × 10(-8) on chromosomes 12 and 22, respectively.

CONCLUSIONS

These results suggest that aspects of temperament might define subtypes of BD that are more clinically and genetically homogenous, which might aid in the identification of predisposing genetic variants.

A new approach of personality and psychiatric disorders: a short version of the Affective Neuroscience Personality Scales

BACKGROUND

The Affective Neuroscience Personality Scales (ANPS) is an instrument designed to assess endophenotypes related to activity in the core emotional systems that have emerged from affective neuroscience research. It operationalizes six emotional endophenotypes with empirical evidence derived from ethology, neural analyses and pharmacology: PLAYFULNESS/joy, SEEKING/interest, CARING/nurturance, ANGER/rage, FEAR/anxiety, and SADNESS/separation distress. We aimed to provide a short version of this questionnaire (ANPS-S).

METHODOLOGY/PRINCIPAL FINDINGS

We used a sample of 830 young French adults which was randomly split into two subsamples. The first subsample was used to select the items for the short scales. The second subsample and an additional sample of 431 Canadian adults served to evaluate the psychometric properties of the short instrument. The ANPS-S was similar to the long version regarding intercorrelations between the scales and gender differences. The ANPS-S had satisfactory psychometric properties, including factorial structure, unidimensionality of all scales, and internal consistency. The scores from the short version were highly correlated with the scores from the long version.

CONCLUSIONS/SIGNIFICANCE

The short ANPS proves to be a promising instrument to assess endophenotypes for psychiatrically relevant science.

Exercise and mental illness: results from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC)

BACKGROUND

Regular exercise is thought to be associated with low rates of mental illness, but this association has been inadequately studied. The purpose of this study was to test the hypotheses that the recommended amount of self-reported vigorous exercise would be cross-sectionally associated with reduced prevalence and incidence of various DSM-IV psychiatric disorders, as well as increased rates of remission.

METHOD

Data were collected from 2001 to 2005 as part of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a 2-wave face-to-face survey conducted by the National Institute on Alcohol Abuse and Alcoholism. For this study, the sample consisted of 23,505 nondisabled adults aged between 18 and 65 years.

RESULTS

Individuals who engaged in vigorous exercise at Wave 2 were significantly more likely than were nonexercisers to be diagnosed with a current psychiatric disorder (adjusted odds ratio [AOR] = 1.22, 95% CI, 1.12-1.34 for the nationally recommended amount vs no exercise), significantly less likely to attain remission from a psychiatric disorder between waves (AOR = 0.77, 95% CI, 0.65-0.91), and significantly more likely to relapse or be newly diagnosed with a psychiatric disorder between waves (AOR = 1.15, 95% CI, 1.02-1.30). Alcohol dependence and bipolar II disorder were the disorders most strongly associated with exercise.

CONCLUSIONS

This investigation suggests that the pursuit of vigorous exercise is associated with a vulnerability to mental illness. This surprising finding may be due to reward-related factors that influence both exercise engagement and the expression of certain psychiatric disorders. Prospective trials will be helpful in further clarifying the associations between exercise and mental illness, as the relationships between the 2 are more complex than previously believed.

Genetic structure of personality factors and bipolar disorder in families segregating bipolar disorder

BACKGROUND

Bipolar disorder (BPD) has been associated with variations in personality dimensions, but the nature of this relationship has been unclear. In this study, the heritabilities of BPD and the Big Five personality factors and the genetic correlations between BPD and personality factors are reported.

METHODS

The participants in this study were 1073 individuals from 172 families of Mexican or Central American ancestry. Heritabilities and genetic correlations were calculated under a polygenic model using the maximum-likelihood method of obtaining variance components implemented in the SOLAR software package.

RESULTS

Heritabilities of 0.49, 0.43, and 0.43 were found for the narrowest phenotype (schizoaffective bipolar and bipolar I), the intermediate phenotype (schizoaffective bipolar, bipolar I, and bipolar II), and the broadest phenotype (schizoaffective bipolar, bipolar I, bipolar II, and recurrent depression), respectively. For the Big Five personality factors, heritabilities were 0.25 for agreeableness, 0.24 for conscientiousness, 0.24 for extraversion, 0.23 for neuroticism, and 0.32 for openness to experience. For the narrowest phenotype, a significant negative correlation (-0.32) with extraversion was found. For the broadest phenotype, negative correlations were found for agreeableness (-0.35), conscientiousness (-0.39), and extraversion (-0.44). A positive correlation (0.37) was found with neuroticism.

LIMITATIONS

It is not possible to determine whether aspects of personality are factors in the development of bipolar disorder or vice versa. The short form of the NEO does not provide the ability to examine in detail which facets of extraversion are most closely related to bipolar disorder or to compare our results with studies that have used the long version of the scale.

CONCLUSIONS

This study establishes a partial genetic basis for the Big Five personality factors in this set of families, while the environmental variances demonstrate that non-genetic factors are also important in their influence on bipolar and personality phenotypes. BPD may be most associated with decreased extraversion (less interaction with one's surroundings) because patients spend more time in depressive than manic states.

BDNF function as a potential mediator of bipolar disorder and post-traumatic stress disorder comorbidity

Bipolar disorder (BD) and post-traumatic stress disorder (PTSD) frequently co-occur among psychiatric patients, leading to increased morbidity and mortality. Brain-derived neurotrophic factor (BDNF) function is associated with core characteristics of both BD and PTSD. We propose a neurobiological model that underscores the role of reduced BDNF function resulting from several contributing sources, including the met variant of the BDNF val66met (rs6265) single-nucleotide polymorphism, trauma-induced epigenetic regulation and current stress, as a contributor to the onset of both illnesses within the same person. Further studies are needed to evaluate the genetic association between the val66met allele and the BD-PTSD population, along with central/peripheral BDNF levels and epigenetic patterns of BDNF gene regulation within these patients.

Biological aspect of hyperthymic temperament: light, sleep, and serotonin

RATIONALE

Hyperthymic temperament is one of several premorbid temperaments putatively associated with bipolar disorder. Several reports suggest that depressive patients with hyperthymic temperament may belong to the proposed soft bipolar spectrum.

OBJECTIVES

To investigate biological aspects of hyperthymic temperament, the present study examined daily activity, sleep time, central serotonergic function, and other relevant variables in relation to hyperthymic temperament in healthy subjects.

METHODS

Fifty six healthy subjects were monitored via the actigraphy system to measure daily total activity, sleep time, and illuminance. A neuroendocrine challenge test was performed to estimate central serotonergic function.

RESULTS

Multiple regression analysis revealed that higher illuminance of daytime, greater fluctuation in sleep time, and lower central serotonergic function significantly and independently predicted hyperthymic temperament scores.

CONCLUSIONS

The present findings suggest that light, sleep, and serotonin are crucial factors in understanding hyperthymic temperament, which may be common to bipolar disorder.

Clinical endophenotypes for bipolar disorder

Although twin, family, and adoption studies demonstrate that bipolar disorder (BPD) is substantially heritable, the molecular genetic basis for this illness remains elusive. Given evidence that genes predisposing to BPD may be transmitted without expression of the clinical phenotype, interest has arisen in developing endophenotypes - indicators of processes mediating between genotype and phenotype. Patients with BPD have subtle neuropsychological abnormalities, even during periods of symptom remission. Some of these neurocognitive deficits are present in unaffected family members of probands with BPD, suggesting that these measures may be quantitative endophenotypes for the disorder. Similarly, BPD is associated with specific personality traits (e.g., reduced inhibition, increased risk-taking) that have been observed in both affected individuals and their family members. In this chapter, we review the evidence for candidate neurocognitive and personality endophenotypes for BPD. We conclude that neurocognitive and personality traits appear to be appropriate endophenotypes for BPD, suggesting that these measures share some genetic factors with the illness.

Temperament and character in patients with bipolar II disorder and recurrent brief depression

OBJECTIVES

We compared the temperament and character profiles of 21 patients with bipolar II disorder, 40 patients with recurrent brief depression (RBD; at least monthly depressive episodes meeting the diagnostic criteria for major depressive episode except for duration that is less than 2 weeks, typically 2-3 days, without fixed relation to menstrual cycle) of which 21 had no history of hypomania and 19 had experienced hypomanic episodes, and 21 age- and sex-matched controls.

METHODS

Assessments included the Montgomery-Åsberg Depression Rating Scale, Hypomania Checklist, and Temperament and Character Inventory-125. Patients with cluster A and B personality disorders were excluded.

RESULTS

Bipolar II and RBD patients had higher harm avoidance (HA) and lower self-directedness (SD) compared with controls. Excluding panic disorder comorbidity effaced this difference in HA and SD (bipolar II only) and harm avoidance. No other differences were found.

CONCLUSIONS

In this first study comparing personality profiles of patients with bipolar II vs RBD, when controlling for confounders, neither bipolar II nor RBD patients differed significantly from healthy controls. The lower SD scores among RBD patients may reflect sampling bias (a higher rate of Axis 2 cluster C disorders).