Temperament and character in mood disorders: influence of DRD4, SERTPR, TPH and MAO-A polymorphisms

Polygenic risk for depression predicting temperament trajectories over 15 years - A general population study

BACKGROUND

A great number of case-control and population-based studies have shown that depression patients differ from healthy controls in their temperament traits. We investigated whether polygenic risk for depression predicts trajectories of temperament traits from early adulthood to middle age.

METHODS

Participants came from the population-based Young Finns Study (n = 2212). The calculation for Polygenic risk for depression (PRS) was based on the most recent genome-wide association study. Temperament traits of Harm Avoidance, Novelty Seeking, Reward Dependence, and Persistence were assessed with the Temperament and Character Inventory in 1997, 2001, 2007, and 2012 (participants being 24-50-year-olds). As covariates, we used depressive symptoms as assessed by a modified version of the Beck Depression Inventory, psychosocial family environment from parent-filled questionnaires, and socioeconomic factors from adulthood.

RESULTS

High PRS predicted higher Persistence from early adulthood to middle age (p = 0.003) when controlling for depressive symptoms, psychosocial family environment, and socioeconomic factors. PRS did not predict trajectories of Novelty Seeking (p = 0.063-0.416 in different models) or Reward Dependence (p = 0.531-0.736). The results remained unaffected when participants with diagnosed affective disorders were excluded. Additionally, we found an interaction between PRS and depressive symptoms when predicting the Harm Avoidance subscale Anticipatory Worry, indicating that the association of Anticipatory Worry with depressive symptoms is stronger in individuals with higher (vs. lower) PRS.

LIMITATIONS

There was some attrition due to the long follow-up.

CONCLUSIONS

High polygenic risk for major depression may predict differences in temperament trajectories among those who have not developed any severe affective disorders.

The Repertoire of Small-Molecule PET Probes for Neuroinflammation Imaging: Challenges and Opportunities beyond TSPO

Neuroinflammation is an adaptive response of the central nervous system to diverse potentially injurious stimuli, which is closely associated with neurodegeneration and typically characterized by activation of microglia and astrocytes. As a noninvasive and translational molecular imaging tool, positron emission tomography (PET) could provide a better understanding of neuroinflammation and its role in neurodegenerative diseases. Ligands to translator protein (TSPO), a putative marker of neuroinflammation, have been the most commonly studied in this context, but they suffer from serious limitations. Herein we present a repertoire of different structural chemotypes and novel PET ligand design for classical and emerging neuroinflammatory targets beyond TSPO. We believe that this Perspective will support multidisciplinary collaborations in academic and industrial institutions working on neuroinflammation and facilitate the progress of neuroinflammation PET probe development for clinical use.

The Dopamine D4 Receptor (DRD4) Exon 3 VNTR Contributes to Adaptive Personality Differences in an Italian Small Island Population

The search for evolutionary forces shaping the diversity of human personality traits encouraged studies that have found that islanders are relatively closed and introverted, with little interest in the external world. The ‘personality gene flow’ hypothesis was proposed to explain the mechanism underlying this difference, suggesting that the frequency of alleles that influence islander personality traits might progressively increase in the gene pools on islands because of selective emigration of individuals not displaying these alleles. We genotyped 96 individuals from the Italian mainland and 117 from Giglio Island, whose residents were previously assessed regarding their personality traits. We genotyped three polymorphisms: the dopamine D4 receptor (DRD4) exon 3 repeat region, the serotonin–transporter SLC6A4 5–HTTLPR indel and the dopamine transporter SLC6A3 DAT1 3′UTR repeat region. Only the DRD4 exon 3 repeat was hypothesised to show varying allele frequencies because this polymorphism could be associated with human migration and personality traits such as extraversion, openness and novelty seeking. As predicted, no differences in allele frequencies were found for the SLC6A4 and SLC6A3 polymorphisms, whereas significant differences were observed in the frequency of the DRD4 exon 3 alleles. The DRD4.2 repeat was more common in mainlanders, as expected, whereas the DRD4.7 allele was over–represented among islanders who never emigrated. This last result contradicts the suggested association of this allele with long–distance migrations. We suggest that emigration might have caused gene flow out the island that resulted in somewhat unpredictable changes in the frequencies of specific alleles, thus influencing islander personality traits. Copyright © 2013 European Association of Personality Psychology

Rats selectively bred for showing divergent behavioral traits in response to stress or novelty or spontaneous yawning with a divergent frequency show similar changes in sexual behavior: the role of dopamine

Sexual behavior plays a fundamental role for reproduction in mammals and other animal species. It is characterized by an anticipatory and a consummatory phase, and several copulatory parameters have been identified in each phase, mainly in rats. Sexual behavior varies significantly across rats even when they are of the same strain and reared under identical conditions. This review shows that rats of the same strain selectively bred for showing a divergent behavioral trait when exposed to stress or novelty (i.e. Roman high and low avoidance rats, bred for their different avoidance response to the shuttle box, and high and low novelty exploration responders rats, bred for their different exploratory response to a novel environment) or a spontaneous behavior with divergent frequency (i.e. low and high yawning frequency rats, bred for their divergent yawning frequency) show similar differences in sexual behavior, mainly in copulatory pattern, but also in sexual motivation. As shown by behavioral pharmacology and intracerebral microdialysis experiments carried out mainly in Roman rats, these sexual differences may be due to a more robust dopaminergic tone present in the mesocorticolimbic dopaminergic system of one of the two sub-lines (e.g. high avoidance, high novelty exploration, and low yawning rat sub-lines). Thus, differences in genotype and/or in prenatal/postnatal environment lead not only to individual differences in temperament and environmental/emotional reactivity but also in sexual behavior. Because of the highly conserved mechanisms controlling reproduction in mammals, this may occur not only in rats but also in humans.

Temperament and Character Inventory in Bipolar Disorder versus Healthy Controls and Modulatory Effects of 3 Key Functional Gene Variants

BACKGROUND

Bipolar disorder (BD) has been associated with temperamental and personality traits, although the relationship is still to be fully elucidated. Several studies investigated the genetic basis of temperament and character, identifying catechol-O-methyltransferase (COMT), brain derived neurotrophic factor (BDNF), and serotonin transporter (5-HTT) gene variants as strong candidates.

METHODS

In the GECO-BIP study, 125 BD patients and 173 HC were recruited. Subjects underwent to a detailed assessment and the temperament and character inventory 125 items (TCI) was administrated. Three functional genetic variants within key candidate genes (COMT rs4680, BDNF rs6265, and the serotonin-transporter-linked polymorphic region (5-HTTLPR)) were genotyped. Univariate and multivariate analyses were performed.

RESULTS

Compared to HC, BD patients showed higher scores in novelty seeking (NS; p = 0.001), harm avoidance (HA; p < 0.001), and self transcendence (St; p < 0.001), and lower scores in self directness (p < 0.001) and cooperativeness (p < 0.001) TCI dimensions. Concerning the genetic analyses, COMT rs4680 was associated with NS in the total sample (p = 0.007) and in the male subsample (p = 0.022). When performing the analysis in the HC and BD samples, the association was confirmed only in HC (p = 0.012), and in the HC male subgroup in particular (p = 0.004). BDNF rs6265 was associated with St in the BD group (p = 0.017).

CONCLUSION

COMT rs4680 may modulate NS in males in the general population. This effect was not detected in BD patients, probably because BD alters the neurobiological basis of some TCI dimensions. BDNF rs6265 seems to modulate St TCI dimension only in BD patients, possibly modulating the previously reported association between rs6265 and BD treatment response. Further studies are needed to confirm our findings.

Genetically-Driven Enhancement of Dopaminergic Transmission Affects Moral Acceptability in Females but Not in Males: A Pilot Study

Moral behavior has been a key topic of debate for philosophy and psychology for a long time. In recent years, thanks to the development of novel methodologies in cognitive sciences, the question of how we make moral choices has expanded to the study of neurobiological correlates that subtend the mental processes involved in moral behavior. For instance, in vivo brain imaging studies have shown that distinct patterns of brain neural activity, associated with emotional response and cognitive processes, are involved in moral judgment. Moreover, while it is well-known that responses to the same moral dilemmas differ across individuals, to what extent this variability may be rooted in genetics still remains to be understood. As dopamine is a key modulator of neural processes underlying executive functions, we questioned whether genetic polymorphisms associated with decision-making and dopaminergic neurotransmission modulation would contribute to the observed variability in moral judgment. To this aim, we genotyped five genetic variants of the dopaminergic pathway [rs1800955 in the dopamine receptor D4 (DRD4) gene, DRD4 48 bp variable number of tandem repeat (VNTR), solute carrier family 6 member 3 (SLC6A3) 40 bp VNTR, rs4680 in the catechol-O-methyl transferase (COMT) gene, and rs1800497 in the ankyrin repeat and kinase domain containing 1 (ANKK1) gene] in 200 subjects, who were requested to answer 56 moral dilemmas. As these variants are all located in genes belonging to the dopaminergic pathway, they were combined in multilocus genetic profiles for the association analysis. While no individual variant showed any significant effects on moral dilemma responses, the multilocus genetic profile analysis revealed a significant gender-specific influence on human moral acceptability. Specifically, those genotype combinations that improve dopaminergic signaling selectively increased moral acceptability in females, by making their responses to moral dilemmas more similar to those provided by males. As females usually give more emotionally-based answers and engage the "emotional brain" more than males, our results, though preliminary and therefore in need of replication in independent samples, suggest that this increase in dopamine availability enhances the cognitive and reduces the emotional components of moral decision-making in females, thus favoring a more rationally-driven decision process.

An attempt to construct a 7-item short version of the temperament and character inventory to predict the treatment response of patients with depression; a validation study

BACKGROUND

The Temperament and Character Inventory (TCI) is a psychological test that is frequently used to assess personality traits. Many studies have shown the potential of the inventory to predict the treatment response of patients with major depressive disorder (MDD). Previously, we showed the association between 10 items of the TCI and the treatment response. In the present study, we reanalyzed the 10 items and aimed to provide cut-off values.

METHODS

This work is a secondary analysis of previously published work. Seventy-three patients were enrolled in the previously done study. Participants were treated with 10-40 mg/day of paroxetine for six weeks, and then the participants completed the TCI. The Montgomery-Asberg Depression Rating Scale (MADRS) was used to evaluate depression. The participants were divided into two groups (responders and non-responders). Using chi-squared tests, we reanalyzed the 10 items that had the strongest association with the treatment response in the previous study. We rated the answers to each item associated with the treatment response as a "1", and the answers associated with a non-response were rated as a "0". We calculated predictive scores using 10 models. Each model consisted of 1-10 scores of the best 1-10 items. We defined cut-off values for predicting treatment responses using a receiver operating characteristic (ROC) curve analysis.

RESULTS

Ranked by the strength of the association with the treatment response, items 174, 137, 70, 237, 106, 191, 34, 232, 161, and 215 of the TCI significantly predicted treatment responses. All predictive scores from models 1 to 10 significantly predicted treatment responses. The predictive score threshold of model 7 was 3/4, with an area under the curve of 0.825, and this model showed the highest odds and likelihood ratios (19.3 and 8.86, respectively).

CONCLUSIONS

We might predict the treatment response of patients with MDD using TCI predictive scoring, including items 174, 137, 70, 237, 106, 191, and 34 and a cut-off value of 3/4.

A meta-analysis of temperament and character dimensions in patients with mood disorders: Comparison to healthy controls and unaffected siblings

BACKGROUND

Cloninger's psychobiological model of personality has been extensively applied to subjects affected by mood disorders (MOOD). However, most studies are widely heterogeneous in terms of sample size, methods of assessment, and selection of participants.

METHODS

We conducted a systematic review of literature and a random effects meta-analysis of studies comparing at least two of the following groups: (a) adults with a primary MOOD diagnosis (Bipolar Disorder (BP) or major depressive disorder (MDD)), (b) their unaffected siblings (SIB) or (c) healthy subjects (HS), and reporting quantitative results from the Tridimensional Personality Questionnaire (TPQ) or the Temperament and Character Inventory (TCI). Subgroup, sensitivity and meta-regression analyses were also conducted.

RESULTS

High Harm Avoidance and low Self-Directedness were consistently associated with MOOD and SIB samples. BP was characterized by higher scores in Novelty Seeking and Self-Transcendence than HS, SIB and MDD. Age seemed to have a negative effect on Novelty Seeking and a positive effect on Harm Avoidance, Cooperativeness and Self-Transcendence. An euthymic mood state was associated with reduced Harm Avoidance, but increased Reward Dependence, Self-Directedness and Cooperativeness.

LIMITATIONS

The quality of the included studies varied and was relatively low. Moreover, publication bias and heterogeneity in the distribution of effect sizes may also have limited our results.

CONCLUSION

High Harm Avoidance and Low Self-Directedness may be trait markers for MOOD in general, while high Novelty Seeking and high Self-Transcendence may be specific to BP. Future studies are needed to disentangle the state-trait effect of each personality dimension.

A Trio of Concerns

This essay assesses the two most significant changes in psychology over the past century: the attempt to localize psychological phenomena in restricted brain sites and the search for genetic contributions to behavior and psychopathology. Although there are advantages to these new developments, they are accompanied by some questionable assumptions. Because the investigators in these domains often relate variation in their biological measures to variation in personality traits evaluated with questionnaires, an analysis of the unique properties of the verbalreport questionnaires is presented. It is suggested that future research on human personality should try to combine semantic reports with behaviors and biological data in order to arrive at more fruitful constructs.

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.

Neurobiological Findings in Youth with Borderline Personality Disorder

This review summarizes recent neurobiological research into youth with borderline personality disorder (BPD) to better delineate the biological factors involved in the development of this disorder. Psychobiological studies when BPD first becomes manifest are of particular interest, because there are fewer confounding factors (e.g., duration of illness, drug abuse, medication, other therapeutic interventions) at this time. This article focuses on recent findings in the field of neuroimaging, neuropsychology, neuroendocrinology, genetics, and pain perception, and it aims to integrate these findings in a developmental psychopathology model of BPD. In studies of clinical samples of adults with BPD, structural imaging studies revealed abnormalities predominantly in the frontolimbic areas. Disturbances in emotional information processing—particularly involving negative stimuli—may mediate affective dysregulation as a core feature of BPD. Genetic studies could reveal that the stability of BPD traits in youth is largely influenced by a combination of genetic and non-shared environmental factors. Hyporesponsiveness to a laboratory stressor indicates an enduring alteration of the hypothalamic–pituitary–adrenal axis. Findings of a higher pain threshold indicate that pain processing is already disturbed during the early stages of BPD, which could contribute to the initiation or maintenance of self-injurious behavior. All biological factors, together with environmental risk factors, may contribute to the core symptoms of BPD: severe emotional and behavioral dysregulation. Further research should investigate the development of BPD in youth by using longitudinal designs to determine whether the neurobiological factors are a cause, an effect, or an epiphenomenon of BPD.

Affective Temperament Profiles of Overactive Bladder Patients

INTRODUCTION

Overactive bladder (OAB) is generally characterized by urinary urgency with or without incontinence and increased frequency of voiding and nocturia. Although animal studies have demonstrated the relationship between defective serotonergic neurotransmission and OAB, its etiology is still unclarified. Temperament profiles are hypothesized to be related with serotonergic activity and are studied in many psychosomatic disorders. Thus, we assume that OAB is related with a certain type of temperament.

METHOD

29 patients, who were admitted to the urology outpatient clinic at Kocaeli University and clinically diagnosed with OAB syndrome, were recruited for the study. Temperament profiles were evaluated with the Temperament Evaluation of Memphis Pisa Paris and San Diego Autoquestionnaire (TEMPS-A). Depressive, hyperthymic, cyclothymic, anxious and irritable temperament scores in patients were compared with those in 25 healthy controls.

RESULTS

Patient and control groups were similar in terms of age (p=.65), sex (p=.64) and educational level (p=.90). Anxious temperament scores were higher (p=.02) and hyperthymic temperament scores were lower (p=.02) in patients with OAB compared to controls. Depressive, cyclothymic and irritable temperament scores were similar in both groups. There was no significant differences between men and women in both groups in terms of different temperament profile scores.

CONCLUSION

Hypothetically, there might be an association between anxious temperament and OAB syndrome reflecting serotonergic dysfunction. However, OAB syndrome must be considered from the aspect of the interdependence of psychosomatic implications in a narrow sense and psychosomatic dimensions due to the psychological predisposition in the individual case.

An investigation of temperament and character inventory items for predicting the response to paroxetine treatment in patients with major depressive disorder

BACKGROUND

Previous studies have reported associations between Temperament and Character Inventory (TCI) dimension scores and the response to treatment in patients with major depressive disorder (MDD). We aimed to determine which TCI items could predict the response to treatment with paroxetine in patients with MDD.

METHODS

Seventy-three patients were enrolled in this study. The participants were treated with 10-40mg/day of paroxetine for six weeks; they then completed the TCI. The Montgomery-Asberg Depression Rating Scale (MADRS) was used to evaluate the patients. The participants were divided into two groups (responders and non-responders). We used a chi-squared test to identify the 10 items with the strongest association with treatment response from among all 240 items on the TCI, and we used a multiple logistic regression analysis to confirm the validity of these 10 items.

RESULTS

Among the TCI dimension scores, only the C score differed significantly between the two groups. We analyzed 10 models using each of the 10 best items. All the models significantly predicted treatment response. The TCI dimensions model also significantly predicted treatment response, but its predictive value was lower than those of the other 10 models.

LIMITATIONS

The responders included the early responders. The results lacked information about responders whose responses were not predicted by the logistic regression models and TCI items.

CONCLUSIONS

Some TCI items showed significant associations with the response to paroxetine treatment in the patients with MDD. Treatment response in patients with MDD may be predicted using only 10 items from the TCI.

From pharmacogenetics to pharmacogenomics: the way toward the personalization of antidepressant treatment

OBJECTIVE

Major depressive disorder is the most common psychiatric disorder, worldwide, yet response and remission rates are still unsatisfactory. The identification of genetic predictors of antidepressant (AD) response could provide a promising opportunity to improve current AD efficacy through the personalization of treatment. The major steps and findings along this path are reviewed together with their clinical implications and limitations.

METHOD

We systematically reviewed the literature through MEDLINE and Embase database searches, using any word combination of "antidepressant," "gene," "polymorphism," "pharmacogenetics," "genome-wide association study," "GWAS," "response," and "adverse drug reactions." Experimental works and reviews published until March 2012 were collected and compared.

RESULTS

Numerous genes pertaining to several functional systems were associated with AD response. The more robust findings were found for the following genes: solute carrier family 6 (neurotransmitter transporter), member 4; serotonin receptor 1A and 2A; brain-derived neurotrophic factor; and catechol-O-methyltransferase. Genome-wide association studies (GWASs) provided many top markers, even if none of them reached genome-wide significance.

CONCLUSIONS

AD pharmacogenetics have not produced any knowledge applicable to routine clinical practice yet, as results were mainly inconsistent across studies. Despite this, the rising awareness about methodological deficits of past studies could allow for the identication of more suitable strategies, such as the integration of the GWAS approach with the candidate gene approach, and innovative methodologies, such as pathway analysis and study of depressive endophenotypes.

Boys' serotonin transporter genotype affects maternal behavior through self-control: a case of evocative gene-environment correlation

Self-control, involving processes such as delaying gratification, concentrating, planning, following instructions, and adapting emotions and behavior to situational requirements and social norms, may have a profound impact on children's adjustment. The importance of self-control suggests that parents are likely to modify their parenting based on children's ability for self-control. We study the effect of children's self-control, a trait partially molded by genetics, on their mothers' parenting, a process of evocative gene-environment correlation. Israeli 3.5-year-old twins (N = 320) participated in a lab session in which their mothers' parenting was observed. DNA was available from most children (N = 228). Mothers described children's self-control in a questionnaire. Boys were lower in self-control and received less positive parenting from their mothers, in comparison with girls. For boys, and not for girls, the serotonin transporter linked polymorphic region gene predicted mothers' levels of positive parenting, an effect mediated by boys' self-control. The implications of this evocative gene-environment correlation and the observed sex differences are discussed.

Male rats that differ in novelty exploration demonstrate distinct patterns of sexual behavior

High- versus low-novelty exploration predicts a variety of behavioral differences. For example, rats selectively bred for high-novelty exploration (bred-high responders, bHR) exhibit exaggerated aggression, impulsivity, and proclivity to addictive behaviors compared with low-novelty reactive rats (bred-low responders, bLRs), which are characterized by a high anxiety/depressive-like phenotype. Since bHR/bLR rats exhibit differences in dopaminergic circuitry and differential response to rewarding stimuli (i.e., psychostimulants, food), the present study examined whether they also differ in another key hedonic behavior-sex. Thus, adult bHR/bLR males were given five 30-min opportunities to engage in sexual activity with a receptive female. Sexual behavior and motivation were examined and compared between the groups. The bHR/bLR phenotype affected both sexual motivation and behavior, with bLR males demonstrating reduced motivation for sex compared with bHR males (i.e., fewer animals copulated, longer latency to engage in sex). The bHR males required more intromissions at a faster pace per ejaculation than did bLR males. Thus, neurobiological differences that affect motivation for drugs of abuse, aggression, and impulsivity in rats also affect sexual motivation and performance.

TPH1 A218C polymorphism and temperament in major depression

BACKGROUND

In major depression, one of the candidate genes possibly affecting the risk and severity of symptoms has been found to be tryptophan hydroxylase (TPH1). Variation in treatment response to antidepressive agents according to TPH1 genotype has also been found in several studies. However, the relationship between temperament and TPH1 genotype in major depression is poorly understood, as only one study has been published so far. There are no earlier studies on the interaction between temperament traits, antidepressive medication response and TPH1 genotype. This interaction was studied in 97 subjects with major depression treated for six weeks with selective serotonine reuptake inhibitors.

METHODS

Temperament dimensions Harm Avoidance (HA), Novelty Seeking (NS), Reward Dependence (RD) and Persistence (P) scores at baseline (1) and endpoint (2) were rated with the Temperament and Character Inventory (TCI) and compared between TPH1 A218C genotypes. Multivariate analysis of co-variance (MANCOVA) was used to analyze the interaction between the TPH1 genotype, treatment response and the different temperament dimensions at baseline and endpoint. In the analysis model, treatment response was used as a covariate and TPH1 genotype as a factor. A post hoc analysis for an interaction between remission status and TPH1 A218C genotype at endpoint HA level was also performed.

RESULTS

The number of TPH1 A-alleles was associated with increasing levels in NS1 and NS2 scores and decreasing levels in HA1 and HA2 scores between TPH1 A218C genotypes. In the MANCOVA model, TPH1 genotype and treatment response had an interactive effect on both HA1 and HA2 scores, and to a lesser degree on NS2 scores. Additionally, an interaction between remission status and TPH1 A218C genotype was found to be associated with endpoint HA score, with a more marked effect of the interaction between CC genotype and remission status compared to A-allele carriers.

CONCLUSIONS

Our results suggest that in acute depression TPH1 A218C polymorphism and specifically the CC genotype together with the information on remission or treatment response differentiates between different temperament profiles and their changes.

Temperamental patterns in female adolescents with borderline personality disorder

A specific composition of temperament traits with high novelty seeking (NS), high harm avoidance (HA), and low reward dependence (RD) has been attributed to adult patients with borderline personality disorder (BPD). This study examined whether an analogue personality profile is specifically associated with adolescent BPD. The female study sample comprised 33 adolescents with BPD, 35 clinical controls (CCs), and 31 healthy controls (HCs). Dimensions of temperament and character were measured according to Cloninger's biopsychosocial model of personality. Significantly higher means of NS and HA but lower means of RD could be determined in the adolescents with BPD compared with the CCs and the HCs. The comparable findings of this specific temperament constellation in adolescents and adult patients with BPD suggest that heritable factors such as temperamental traits may contribute to the vulnerability for developing BPD. Early identification of a "borderline temperament" may facilitate early intervention and lower the risk for developing BPD.

Role of substance abuse comorbidity and personality on the outcome of depression in bipolar disorder: harm avoidance influences medium-term treatment outcome

Comorbid conditions are frequent in bipolar disorder (BD) and may complicate the treatment and course of illness. We investigated the role of substance use disorder (SUD), axis II personality disorders (PD) and continuous personality traits on the medium-term outcome (6 months) of treatment for bipolar depression. One hundred and thirty-nine BD patients meeting criteria for a depressive episode were included in the study. SUD and PD were diagnosed according to structured interviews. Personality dimensions were evaluated by the Temperament and Character Inventory. Depressive severity over time was evaluated by the Hamilton Rating Scale for Depression. Neither PD nor SUD influenced the outcome of depression. Variables independently associated with a poor outcome were a high baseline severity and high scores for the temperamental trait of Harm Avoidance. Though several limitations characterize the present study, neurotic personality traits seem to be associated with a slower recovery from depressive symptoms in BD, independently from their initial severity.

A meta-analysis of temperament in axis I psychiatric disorders

This article reports on a meta-analysis of Cloninger's temperament dimensions (novelty seeking, harm avoidance, reward dependence, and persistence) in individuals with lifetime psychiatric disorders compared with controls and on interdisorder comparisons between these disorders. Nine disorders from 75 studies were included in the meta-analyses. The most consistent feature was elevated harm avoidance: compared with the controls, harm avoidance was higher in all diagnostic groups studied except for those with alcohol use disorders. The increase in effect sizes in harm avoidance scores varied from a very large (d = 2.66) in social phobia to a small effect (effect size, d = 0.29) in alcohol use disorders. In other dimensions, differences between cases and controls were relatively small. However, in pairwise comparisons, notable differences also in other dimensions emerged: in novelty seeking, the lowest scores were in social phobia (d = -0.87) and the highest in bulimia nervosa (d = 0.33); in reward dependence, the lowest scores were in schizophrenia (d = -0.36) and the highest in social phobia (d = 0.12); and in persistence, the lowest scores were in social phobia (d = -0.30) and the highest in anorexia nervosa (d = 0.49). The provided data should be taken into account in the future studies on suggestive vulnerability markers for psychiatric morbidity.

Pharmacogenomics of antidepressant induced mania: a review and meta-analysis of the serotonin transporter gene (5HTTLPR) association

BACKGROUND

Antidepressants can trigger a rapid mood switch from depression to mania. Identifying genetic risk factors associated with antidepressant induced mania (AIM) may enable individualized treatment strategies for bipolar depression. This review and meta-analysis evaluates the evidence for association between the serotonin transporter gene promoter polymorphism (5HTTLPR) and AIM.

METHODS

Medline up to November 2009 was searched for key words bipolar, antidepressant, serotonin transporter, SLC6A4, switch, and mania.

RESULTS

Five studies have evaluated the SLC6A4 promoter polymorphism and AIM in adults (total N=340 AIM+ cases, N=543 AIM- controls). Although a random effects meta-analysis showed weak evidence of association of the S allele with AIM+ status, a test of heterogeneity indicated significant differences in estimated genetic effects between studies. A similar weak association was observed in a meta-analysis based on a subset of three studies that excluded patients on mood stabilizers; however the result was again not statistically significant.

LIMITATIONS

Few pharmacogenomic studies of antidepressant treatment of bipolar disorder have been published. The completed studies were underpowered and often lacked important phenotypic information regarding potential confounders such as concurrent use of mood stabilizers or rapid cycling.

CONCLUSIONS

There is insufficient published data to confirm an association between 5HTTLPR and antidepressant induced mania. Pharmacogenomic studies of antidepressant induced mania have high potential clinical impact provided future studies are of adequate sample size and include rigorously assessed patient characteristics (e.g. ancestry, rapid cycling, concurrent mood stabilization, and length of antidepressant exposure).

Can onset and recovery in depression be predicted by temperament? A systematic review and meta-analysis

BACKGROUND

Behavioural inhibition and more specifically harm avoidance temperament dimension (HA) has been found to be associated with depression. Temperament and Character Inventory (TCI) by Cloninger et al. is the most widely used instrument in the assessment of temperament. The aims of the present study were to explore 1) if current or future depressive symptoms in non-clinical adult sample can be explained by TCI temperament dimensions, and 2) if recovery from major depression (MDD) during the acute phase of treatment is predictable by TCI temperament dimensions.

METHOD

Literature search from eight databases. Systematic review and meta-analysis.

RESULTS

High HA was associated with current depressive symptoms in 11/12 studies and with depressive trait in 3/4 studies. In MDD studies, a consistent negative change in HA was found during treatment and this change was even more clearly associated with treatment response.

LIMITATIONS

The studies with general population samples were heterogeneous in methodology. Most of the intervention studies were of case-control design.

CONCLUSIONS

HA is indisputably associated with the risk and treatment response in depression.

Early life stress and child temperament style as predictors of childhood anxiety and depressive symptoms: findings from the longitudinal study of Australian children

Objective. The purpose of this study was to determine whether the relationship between stressful infant environments and later childhood anxiety and depressive symptoms varies as a function of individual differences in temperament style. Methods. Data was drawn from the Longitudinal Study of Australian Children (LSAC). This study examined 3425 infants assessed at three time points, at 1-year, at 2/3 years and at 4/5 years. Temperament was measured using a 12-item version of Toddler Temperament Scale (TTS) and was scored for reactive, avoidant, and impulsive dimensions. Logistic regression was used to model direct relationships and additive interactions between early life stress, temperament, and emotional symptoms at 4 years of age. Analyses were adjusted for socioeconomic status, parental education, and marital status. Results. Stressful family environments experienced in the infant's first year of life (high versus low) and high reactive, avoidant, and impulsive temperament styles directly and independently predicted anxiety and depressive problems in children at 4 years of age. There was no evidence of interaction between temperament and family stress exposure. Conclusions. Both infant temperament and stress exposures are independent and notable predictors of later anxiety and depressive problems in childhood. The risk relationship between stress exposure in infancy and childhood emotion problems did not vary as a function of infant temperament. Implications for preventive intervention and future research directions are discussed.

Differences in temperament and character dimensions in patients with bipolar I or II or major depressive disorder and general population subjects

BACKGROUND

Whether temperament and character differ between bipolar disorder (BD) and major depressive disorder (MDD) patients and general population subjects, or between BD I and BD II patients, remains unclear.

METHOD

BD patients (n=191) from the Jorvi Bipolar Study and MDD patients (n=266) from the Vantaa Depression Study (VDS) and the Vantaa Primary Care Depression Study were interviewed at baseline, at 6 and 18 months, and in the VDS at 5 years. A general population comparison group (n=264) was surveyed by mail. BD patients' scores on the Temperament and Character Inventory-Revised were compared at an index interview, when levels of depression and mania were lowest, with scores of MDD patients and controls. BD I (n=99) and BD II (n=92) patients were compared.

RESULTS

Compared with controls, both BD and MDD patients had higher harm avoidance [odds ratio (OR) 1.027, p<0.001 and OR 1.047, p<0.001, respectively] and lower persistence (OR 0.983, p=0.006 and OR 0.968, p<0.001, respectively) scores. Moreover, BD patients had lower self-directedness (OR 0.979, p=0.003), MDD patients lower reward dependence (OR 0.976, p=0.002) and self-transcendence (OR 0.966, p<0.001) scores. BD patients scored lower in harm avoidance (OR 0.980, p=0.002) and higher in novelty seeking (OR 1.027, p<0.001) and self-transcendence (OR 1.028, p<0.001) than MDD patients. No differences existed between BD I and II patients.

CONCLUSIONS

The patterns of temperament and character dimensions differed less between BD and MDD patients, than patients from their controls. The most pronounced difference was higher novelty seeking in BD than MDD patients. The dimensions investigated are unlikely to differ between BD I and BD II patients.

The 5-HTTLPR polymorphism and eating disorders: a meta-analysis

OBJECTIVE

Eating disorders are influenced by both environmental factors and genes. The 5-HTTLPR polymorphism of serotonin transporter gene has been suggested as a good candidate. This meta-analysis was undertaken: (1) to investigate the association between 5-HTTLPR and eating disorders considered as a whole, including anorexia (AN), bulimia (BN), and binge eating disorder (BED); (2) to extend recently reported findings on the association between 5-HTTLPR and AN-BN.

METHOD

PubMed, ISI, and PsycINFO databases were searched for studies published until October 2009. Fifteen studies have been included. Data were analyzed with the Cochrane Collaboration Review Manager Software. Quality of studies and publication bias were assessed.

RESULTS

An association between S allele and eating disorders, in particular AN, has been found.

DISCUSSION

To be carrier of the 5-HTTLPR S allele seem to represent a risk factor for eating disorders, especially for AN. However, considering the reported high between-study heterogeneity, future studies should focus on more homogeneous endophenotype.

The influence of psychiatric screening in healthy populations selection: a new study and meta-analysis of functional 5-HTTLPR and rs25531 polymorphisms and anxiety-related personality traits

BACKGROUND

A genetic liability for anxiety-related personality traits in healthy subjects has been associated with the functional serotonin transporter promoter polymorphism (5-HTTLPR), although the data are somewhat conflicting. Moreover, only one study has investigated the functional significance of the 5-HTTLPR/rs25531 haplotypes in relation to anxiety traits in healthy subjects. We tested whether the 5-HTTLPR polymorphism and the 5-HTTLPR/rs25531 haplotypes are linked to Harm Avoidance (HA) using an association study (STUDY I) and a meta-analytic approach (STUDY II).

METHODS

STUDY I: A total of 287 unrelated Italian volunteers were screened for DSM-IV Axis I disorders and genotyped for the 5-HTTLPR and rs25531 (A/G) polymorphisms. Different functional haplotype combinations were also analyzed. STUDY II: A total of 44 studies were chosen for a meta-analysis of the putative association between 5-HTTLPR and anxiety-related personality traits.

RESULTS

STUDY I: In the whole sample of 287 volunteers, we found that the SS genotype and S'S' haplotypes were associated with higher scores on HA. However, because the screening assessed by Mini-International Neuropsychiatric Interview (M.I.N.I.) showed the presence of 55 volunteers affected by depression or anxiety disorders, we analyzed the two groups ("disordered" and "healthy") separately. The data obtained did indeed confirm that in the "healthy" group, the significant effects of the SS genotype and S'S' haplotypes were lost, but they remained in the "disordered" group. STUDY II: The results of the 5-HTTLPR meta-analysis with anxiety-related traits in the whole sample confirmed the association of the SS genotype with higher anxiety-related traits scores in Caucasoids; however, when we analyzed only those studies that used structured psychiatric screening, no association was found.

CONCLUSIONS

This study demonstrates the relevance to perform analyses on personality traits only in DSM-IV axis I disorder-free subjects. Furthermore, we did not find an association between functional serotonin transporter gene polymorphisms and anxiety traits in healthy subjects screened through a structured psychiatric interview.

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).

The role of dopamine in bipolar disorder

OBJECTIVE

Despite effective pharmacological treatments for bipolar disorder, we still lack a comprehensive pathophysiological model of the illness. Recent neurobiological research has implicated a number of key brain regions and neuronal components in the behavioural and cognitive manifestations of bipolar disorder. Dopamine has previously been investigated in some depth in bipolar disorder, but of late has not been a primary focus of attention. This article examines the role of dopamine in bipolar disorder, incorporating recent advances into established models where possible.

METHODS

A critical evaluation of the literature was undertaken, including a review of behavioural, neurochemical, receptor, and imaging studies, as well as genetic studies focusing on dopamine receptors and related metabolic pathways. In addition, pharmacologic manipulation of the central dopaminergic pathways and comparisons with other disease states such as schizophrenia were considered, principally as a means of exploring the hypothesised models.

RESULTS

Multiple lines of evidence, including data from pharmacological interventions and structural and functional magnetic resonance imaging studies, suggest that the dopaminergic system may play a central role in bipolar disorder.

CONCLUSION

Future research into the pathophysiological mechanisms of bipolar disorder and the development of new treatments for bipolar disorder should focus on the dopaminergic system.

Association between the estrogen receptor TA polymorphism and Harm avoidance

In the last decade a large number of studies focused on the recognition of gene variants modulating temperamental traits. The gene coding for the estrogen receptor alpha (ESR1) appears to be an interesting candidate and it has been found to be linked to Harm avoidance (HA). The aim of the present study was to investigate whether the ESR1 TA dinucleotide repeat polymorphism is associated with HA temperamental trait in a sample of Caucasian University students. One hundred ninety healthy subjects were genotyped for ESR1 TA dinucleotide repeat polymorphism and were administered the Temperament and Character Inventory (TCI). ESR1 TA repeat lengths were dichotomized into short and long categories. ANOVA was used to examine the influence of ESR1 variants (short/long) on the means of the TCI HA scores. HA was significantly associated with age and gender in our sample, being higher in older and female subjects. In the global sample as well as in men and women separately, individuals carrying the S/S variant showed significantly higher HA scores. Further analysis on the HA subscales revealed that specific differences could exist between men and women. Our results further suggest a possible role of ESR1 variants on HA. Further research is needed to replicate our findings as well as to better explore the neuro-biological mechanisms of the modulation of ESR1 on HA.

Minor genetic variants of the dopamine D4 receptor (DRD4) polymorphism are associated with novelty seeking in healthy Japanese subjects

Although an association between the dopamine receptor D4 (DRD4) gene and personality traits had been previously investigated, results from previous studies were not conclusive. This may be due to the method of grouping used, which categorized the gene population into two groups based on the length of the variable number of tandem repeats (VNTR) in exon 3. In the present study, we categorized 616 healthy Japanese subjects into more than two groups by further subdividing the DRD4 48-bp VNTR polymorphism, and compared Temperament and Character Inventory (TCI) scores among the groups. A significant difference was found between the DRD4 48-bp VNTR polymorphism and novelty seeking (p=0.016). The novelty-seeking scores in the subjects carrying the 5/5 genotype were significantly higher than in those carrying the 2/2 genotype (p=0.002) or the 4/4 genotype (p=0.005). However, when the conventional method of grouping was used (i.e., short alleles vs. long alleles), there were no significant associations between the DRD4 VNTR polymorphism and any TCI scores. Our results suggest that minor 5-repeat allele is associated with high novelty-seeking scores in healthy Japanese subjects.

Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seeking

Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic (SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2) and dopaminergic genes (SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH), which have been previously reported to be implicated with personality traits. One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire. From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking. The effect of rs927544 could be replicated for the novelty seeking subscale extravagance, and the same SNP was also associated with extravagance in the combined samples. Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype.

Serotonin receptor HTR1A and HTR2C variants and personality traits in suicide attempters and controls

INTRODUCTION

Serotonin has been extensively studied in relation to both personality features and suicidal behaviours.

OBJECTIVE

In this study, we considered the association between the serotonin receptor 1A (HTR1A) and 2C (HTR2C) SNPs and personality traits, as measured by the Temperament and Character Inventory (TCI), in a sample of suicide patients and healthy volunteers.

METHODS

The SNPs considered were, for HTR1A rs1423691, rs878567 and rs6295, and for HTR2C rs547536, rs2192372, rs6318, rs2428707, rs4272555 and rs1801412. The sample was composed of three groups: two German samples, consisting of a healthy control group of 289 subjects (42.6% males, mean age: 45.2+/-14.9) and a psychiatric patient group of 111 suicide attempters (38.7% males, mean age: 39.2+/-13.6), and an Italian sample, composed of 64 mood disorder patients (35.9% males, mean age: 43.0+/-14.8). In the German samples all the SNPs were investigated, while in the Italian sample only the HTR1A rs6295 and the HTR2C rs6318 SNPs were considered.

RESULTS

Controlling for sex, age and educational level, single markers and haplotypes were not or only marginally associated with personality dimensions.

CONCLUSIONS

Our study does not support the role of HTR1A and HTR2C gene variants on personality traits in both healthy volunteers and mood disorder patients.

Adaptations in pre- and postsynaptic 5-HT1A receptor function and cocaine supersensitivity in serotonin transporter knockout rats

RATIONALE

While individual differences in vulnerability to psychostimulants have been largely attributed to dopaminergic neurotransmission, the role of serotonin is not fully understood.

OBJECTIVES

To study the rewarding and motivational properties of cocaine in the serotonin transporter knockout (SERT-/-) rat and the involvement of compensatory changes in 5-HT1A receptor function are the objectives of the study.

MATERIALS AND METHODS

The SERT-/- rat was tested for cocaine-induced locomotor activity, cocaine-induced conditioned place preference, and intravenous cocaine self-administration. In addition, the function and expression of 5-HT1A receptors was assessed using telemetry and autoradiography, respectively, and the effect of 5-HT1A receptor ligands on cocaine's psychomotor effects were studied.

RESULTS

Cocaine-induced hyperactivity and conditioned place preference, as well as intravenous cocaine self-administration were enhanced in SERT-/- rats. Furthermore, SERT-/- rats displayed a reduced hypothermic response to the 5-HT1A receptor agonist 8-OHDPAT. S-15535, a selective somatodendritic 5-HT1A receptor agonist, reduced stress-induced hyperthermia (SIH) in wild-type controls (SERT+/+), while it increased SIH in SERT-/- rats. As 5-HT1A receptor binding was reduced in selective brain regions, these thermal responses may be indicative for desensitized 5-HT1A receptors. We further found that both 8-OHDPAT and S-15535 pretreatment increased low-dose cocaine-induced locomotor activity in SERT-/- rats, but not SERT+/+ rats. At a high cocaine dose, only SERT+/+ animals responded to 8-OHDPAT and S-15535.

CONCLUSION

These data indicate that SERT-/- -associated 5-HT1A receptor adaptations facilitate low-dose cocaine effects and attenuate high-dose cocaine effects in cocaine supersensitive animals. The role of postsynaptic and somatodendritic 5-HT1A receptors is discussed.

Temperament and character of suicide attempters

Temperamental features are strongly associated with suicidal behaviors both in general population and clinical samples. In the present study we considered the association between personality traits, measured by Temperament and Character Inventory (TCI), and suicidal behavior. We analyzed five samples: a German control sample of 1148 healthy individuals; 144 German suicide attempters affected by Mood (n=101), Schizophrenia spectrum (n=20) and Borderline Personality (n=23) Disorders; 46 Italian suicide attempters affected by Mood Disorders (UP=15; BP=31); 76 German non-suicide Mood Disorder patients; 147 Italian non-suicide Mood Disorder patients. Suicide attempters showed higher scores in Harm Avoidance (HA) and lower scores in Self-Directedness (SD) and Cooperativeness (C), when compared to controls. Nevertheless, comparing the German and the Italian suicide attempter groups with the non-suicide Mood Disorder patient groups, no differences were detected. This could be due to the effect of Mood Disorder on personality. In conclusion, the present study reveals the difficulty to disentangle the personality profile of suicide attempters from their psychopathology. Those findings may be useful for cautions in further dissecting this complex phenotype.

Association of MAO-A variant with complicated grief in major depression

BACKGROUND/AIMS

It has been suggested that monoamine oxidase A (MAO-A) activity is involved in the pathogenesis of major depression. Bereavement-related complicated grief significantly increases the risk of major depression and has been shown to be influenced by serotonergic tonus, possibly conferred by MAO-A activity. Complicated grief--whose inclusion in DSM-V as a separate mental disorder is under discussion--has been shown to be a distinct syndrome with symptoms not seen in depression. Therefore, in the present study, genetic variation in the MAO-A gene was investigated for its influence on complicated grief in major depression.

METHODS

Sixty-six unrelated Caucasian patients (41 female, 25 male) with major depression and a history of bereavement were evaluated for complicated grief using the Inventory of Complicated Grief (ICG), the posttraumatic stress reaction after the loss by means of the Impact of Event Scale (IES-R) and further psychopathological measures. Patients were additionally genotyped for the functional variable number tandem repeat (VNTR) in the promoter region of the MAO-A gene.

RESULTS

The more active longer allele of the MAO-A VNTR was significantly associated with complicated grief in the female subgroup of patients (chi(2) = 9.471, p = 0.002, OR = 9.208, 95% CI 2.129-38.899, Bonferroni-corrected p = 0.012), whereas there was no such effect in male patients. Higher posttraumatic stress reaction was only nominally associated with the more active longer allele of the MAO-A VNTR in the female subgroup of patients (genotypes: chi(2) = 5.939, p = 0.015, OR = 5.333, 95% CI 1.366-20.557, Bonferroni-corrected p = 0.087). No significant associations of MAO-A VNTR with the severity of depressive symptoms (Beck Depression Inventory), anxiety symptoms (Spielberger State-Trait Anxiety Inventory), general mental health (Brief Symptom Inventory), or perceived social support (F-SozU) were found (all p > 0.10).

CONCLUSION

The present pilot study for the first time suggests a gender-specific contribution of the more active MAO-A VNTR variant to an increased vulnerability for complicated grief as a potential intermediate phenotype of major depression.

Depression like characteristics of 5HTTLPR polymorphism and temperament in excessive internet users

INTRODUCTION

Excessive internet use (EIU) has been reported to be comorbid with depression and the manifestation of its symptoms. This study examines the characteristics of excessive internet users that are similar to those of patients with depressive disorders in terms of serotonin transporter gene expression and harm avoidance.

METHODS

91 male adolescents with EIU and 75 healthy comparison subjects were recruited. Between group comparisons were made on genetic polymorphisms of the serotonin transport gene and with respect to novelty seeking and harm avoidance (HA) of Cloninger's Temperament Character Inventory.

RESULTS

The homozygous short allelic variant of the serotonin transporter gene (SS-5HTTLPR) is more frequent in the EIU group (chi(2)=4.38, df=1, p<0.05). The HA and Beck Depression Inventory (BDI) scores were significantly higher in the EIU group than in the healthy comparison group (t=7.03, df=164, p<0.01; t=2.12, df=164, p=0.04). EIU subjects expressing SS-5HTTLPR also showed higher HA (HA1, HA2, HA4, and total HA) and Young's internet addiction scale scores than EIU subjects expressing the other serotonin transporter gene allele variants (t=2.47, df=89, p=0.01; t=2.33, df=89, p=0.02; t=2.17, df=89, p=0.03; t=2.25, df=89, p=0.03; t=2.93, df=89, p<0.01 respectively).

CONCLUSIONS

The EIU group had higher SS-5HTTLPR frequencies, harm avoidance, and BDI scores. SS-5HTTLPR expression was closely related to harm avoidance in EIU. The results of this study suggest that EIU subjects may have genetic and personality traits similar to depressed patients.

Evidence for a gene-gene interaction in predicting children's behavior problems: association of serotonin transporter short and dopamine receptor D4 long genotypes with internalizing and externalizing behaviors in typically developing 7-year-olds

Recent work on the molecular genetics of complex traits in typical and atypical human development has focused primarily on associations of single genes with behavior. Disparate literature suggests that the presence of one or two copies of the short allele of the serotonin transporter (5-HTT) gene and the long allele (7-repeat allele) version of the dopamine receptor D4 (DRD4) gene predicts internalizing- and externalizing-related behaviors, respectively. Apparently for the first time in the extant literature, we report a gene-gene statistical interaction on behavior problems in a group of typically developing children at age 7. DNA was extracted from buccal cells collected from 108 children and genotyped for short and long alleles of the 5-HTT gene and the short (2-5 repeats) versus long (6-8 repeats) allele of the DRD4 gene. Mothers completed the Child Behavior Checklist. As predicted, children with one or two copies of the short allele of the 5-HTT gene and the long allele version of the DRD4 gene exhibited significantly more internalizing and externalizing behaviors at age 7 than children with other combinations of the 5-HTT and DRD4 short and long genotypes. As well, children with the 5-HTT long and DRD4 long genotypes had the lowest reported scores on internalizing and externalizing behaviors at age 7, suggesting that the presence of the 5-HTT long genotype may serve as a protective factor against these behaviors in children with the long DRD4 genotype. Implications of these findings for understanding cumulative biological risk and protective factors in childhood behavior problems and psychopathology are discussed.

Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data

BACKGROUND

Two variants in the dopamine D4 receptor (DRD4) gene have been reported to be associated with human approach-related traits such as novelty seeking and extraversion. However, the strength of evidence for this association remains uncertain.

METHODS

We conducted a meta-analysis of published studies of the association between the DRD4 gene variable number of tandem repeats (VNTR) and C-521T polymorphisms and human approach-related personality traits, including novelty seeking, extraversion, and impulsivity, restricted to adult samples recruited from nonpsychiatric populations, and extended on this literature by attempting to confirm any evidence of association in a replication sample (n = 309) selected for extreme scores on the extraversion subscale of the Eysenck Personality Questionnaire from a large (n = 40,090) population-based sample.

RESULTS

Our initial meta-analysis supported the association of the DRD4 C-521T polymorphism, but not the VNTR polymorphism, with approach-related traits. This conclusion was qualified by evidence of significant publication bias and the failure to detect association in a replication sample comprising individuals at the extremes of the trait distribution. The association of the C-521T polymorphism observed in our initial meta-analysis was robust to the inclusion of these new data, but our revised meta-analysis indicated that the association was present for measures of novelty seeking and impulsivity but not for measures of extraversion.

CONCLUSIONS

The DRD4 gene may be associated with measures of novelty seeking and impulsivity but not extraversion. The association of the C-521T variant with these measures, if genuine, may account for up to 3% of phenotypic variance.

An interaction between the norepinephrine transporter and monoamine oxidase A polymorphisms, and novelty-seeking personality traits in Korean females

The personality traits associated with the noradrenergic system have not yet been clearly established. In the present study, we investigated the variable number of tandem repeats (VNTR) polymorphism of the norepinephrine transporter (NET) and monoamine oxidase A (MAOA), which are major components of the adrenergic system, to elucidate their relationship with personality. A total of 245 normal female Koreans (age 23.05+/-3.07 years, mean+/-SD) volunteered to take part in this study. They filled out a Korean version of the Temperament and Character Inventory (TCI) and were genotyped for the NET and MAOA-VNTR; the NET T-182C and MAOA-uVNTR polymorphisms were checked. We found significant main effect of NET genotype on novelty seeking (NS) score (F=5.43, p=0.021) and significant interaction between the NET and MAOA-uVNTR polymorphisms on NS score (F=11.06, p=0.001). However, there were no relationship between MAOA-uVNTR polymorphisms and NS score, and no association with other temperamental dimensions and these two polymorphisms. Our findings suggest that this functional polymorphism in the noradrenergic gene is associated with novelty seeking in Korean females.

Monoamine oxidase A variant influences antidepressant treatment response in female patients with Major Depression

The monoamine oxidase A (MAO-A) has been suggested to be involved in the pathogenesis as well as the pharmacological treatment of Major Depression. In the present study, 340 patients with a Major Depressive Episode (f=194, m=146; DSM-IV) of Caucasian descent were genotyped for the functional MAO-A VNTR. The clinical response to antidepressive pharmacological treatment was assessed by weekly intra-individual changes of HAM-D-21 scores over six weeks. The longer MAO-A alleles (3a, 4, 5) conferred a significant risk of slower and less efficient overall response over the course of 6 weeks of antidepressant treatment in patients with Major Depression, with the effect being restricted to female patients (p=0.028; corrected for multiple testing). The present results suggest that high-activity MAO-A genotypes possibly by consecutively decreased serotonin and/or norepinephrine availability negatively influence antidepressant treatment response during the first six weeks of pharmacological treatment in female patients with Major Depression.

Pharmacogenetics of major depression: insights from level 1 of the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial

Major depression is a serious mental illness frequently associated with devastating consequences for those affected. Suicide rates are significantly elevated, creating a sense of urgency to identify effective yet safe treatment options. A plethora of antidepressants are available on the market today, designed to act on different neurotransmitter systems in the brain, providing the clinician with several treatment strategies. There is, however, very little guidance as to which antidepressant may be most successful in a certain individual. Biomarkers that can predict treatment outcome would thus be of great value, shortening the time until remission and reducing costs for the healthcare system by reducing unsuccessful treatment attempts. The proven contribution of heredity to major depression risk suggests that genetic markers may be good biomarkers for treatment outcome.The Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study and a large ancillary pharmacogenetic study in 1953 STAR*D participants constitute the largest effort to date to identify genetic predictors of antidepressant treatment outcome. In this review, the results of candidate gene studies carried out so far are summarized and discussed, and some future directions are proposed.

Dopamine dysregulation syndrome: implications for a dopamine hypothesis of bipolar disorder

OBJECTIVE

Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder.

METHOD

A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles.

RESULTS

Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper.

CONCLUSION

Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson's disease, administration of high-dose dopamine precursors can produce a 'maniform' picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

Acute and constitutive increases in central serotonin levels reduce social play behaviour in peri-adolescent rats

RATIONALE

Serotonin is an important modulator of social behaviour. Individual differences in serotonergic signalling are considered to be a marker of personality that is stable throughout lifetime. While a large body of evidence indicates that central serotonin levels are inversely related to aggression and sexual behaviour in adult rats, the relationship between serotonin and social behaviour during peri-adolescence has hardly been explored.

OBJECTIVE

To study the effect of acute and constitutive increases in serotonin neurotransmission on social behaviour in peri-adolescent rats.

MATERIALS AND METHODS

Social behaviour in peri-adolesent rats (28-35 days old) was studied after genetic ablation of the serotonin transporter, causing constitutively increased extra-neuronal serotonin levels, and after acute treatment with the serotonin reuptake inhibitor fluoxetine or the serotonin releasing agent 3,4-methylenedioxymethamphetamine (MDMA). A distinction was made between social play behaviour that mainly occurs during peri-adolescence, and non-playful social interactions that are abundant during the entire lifespan of rats.

RESULTS

In serotonin transporter knockout rats, social play behaviour was markedly reduced, while non-playful aspects of social interaction were unaffected. Acute treatment with fluoxetine or MDMA dose-dependently inhibited social play behaviour. MDMA also suppressed non-playful social interaction but at higher doses than those required to reduce social play. Fluoxetine did not affect non-playful social interaction.

CONCLUSIONS

These data show that both acute and constitutive increases in serotonergic neurotransmission reduce social play behaviour in peri-adolescent rats. Together with our previous findings of reduced aggressive and sexual behaviour in adult serotonin transporter knockout rats, these data support the notion that serotonin modulates social behaviour in a trait-like manner.

Suicidal risks among 2826 Sardinian major affective disorder patients

OBJECTIVE

We estimated risks of suicidal behaviors in 2826 mood-disorder patients evaluated and followed in a Sardinian mood disorders research center over the past 30 years.

METHOD

We determined rates of suicidal ideation, attempts, and suicides, with associated risk factors, in men and women with DSM-IV bipolar I (BP-I; n = 529), BP-II; (n = 314), or major depressive disorders (MDD; n = 1983), at risk for an average of 11 years of illness.

RESULTS

Observed rates (% of patients/year) of suicide ranked: BP-II (0.16) > or = BP-I (0.14) > MDD (0.05); attempts: BP-I (1.52) > BP-II (0.82) > MDD (0.48); ideation: BP-II (42.7) > MDD (33.8) > BP-I (22.7). The ratio of attempts/suicides (lethality index) ranked: BP-II (5.12) < MDD (9.60) < or = BP-I (10.8). Male/female risk-ratios were greater for suicide than attempts or ideation. One-third of all reported acts occurred within the first year of illness, and earliest among MDD patients. Factors associated independently with suicidal acts included BP diagnosis, hospitalizations/person, and early illness-onset; factors associated with suicidal ideation were having an affective temperament, BP-II diagnosis, and higher suicidality-corrected depression score at intake.

CONCLUSION

Suicidal behaviors were more prevalent among BPD than MDD out-patients.

Serotonin transporter deficiency in rats improves inhibitory control but not behavioural flexibility

Impulsivity and aggression have been suggested to inversely correlate with central serotonin (5-HT) levels in a trait-like manner. However, this relationship is far from straightforward. In the present study we addressed the effect of lifelong reduced or absent serotonin transporter (SERT) function, which is associated with constitutively increased extracellular 5-HT levels, on impulsivity and aggression. We used unique SERT knockout rats in a resident-intruder test, five-choice serial reaction time task and serial reversal learning task to assay aggression, inhibitory control and behavioural flexibility, respectively. Homozygous SERT knockout rats (SERT( -/-)) displayed reduced aggression and improved inhibitory control, but unchanged behavioural flexibility. The behavioural phenotype of heterozygous SERT knockout rats (SERT( +/-)) was not different from that of wild-type controls in any of the behavioural paradigms. We determined monoamine (metabolite) tissue levels in the medial prefrontal cortex, orbitofrontal cortex, lateral hypothalamus, raphe nuclei and cerebrospinal fluid, and found that the 5-HT levels, but not other monoamine tissue levels, were reduced in SERT( -/-) rats. In addition, the 5-hydroxyindoleacetic acid (5-HIAA)/5-HT ratio in cerebrospinal fluid was increased in these rats. In conclusion, our data show that the absence of the SERT affects aggression and inhibitory control, but not behavioural flexibility, characteristics that may reflect the trait-like consequences of constitutive changes in central 5-HT levels.

5-HT2A SNPs and the Temperament and Character Inventory

Temperamental traits, the most basic part of personality, have been largely correlated with neurotransmitter systems and are under genetic control. Among serotonin candidates, the 2A receptor (5-HT(2A)) received considerable attention. We analyzed four SNPs (rs643627, rs594242, rs6311 and rs6313) in the 5-HT(2A) gene and their association with personality traits, as measured with the Temperament and Character Inventory (TCI). The sample was composed of three sub-groups: two German sub-samples, consisting of a healthy group of 289 subjects (42.6% males, mean age: 45.2+/-14.9) and a psychiatric patient group of 111 suicide attempters (38.7% males, mean age: 39.2+/-13.6), and an Italian sub-sample, composed of 60 mood disorder patients (35.0% males, mean age: 44.0+/-14.8). Controlling for sex, age and educational level, the SNPs were not strongly associated with personality dimensions. Only the rs594242 showed an association with Self-Directedness (p=0.003) in the German sample, while rs6313 was marginally associated with Novelty Seeking (p=0.01) in the Italian sample. We conclude that 5-HT(2A) SNPs may marginally modulate personality traits but further studies are required.

Pharmacogenetic studies in depression: a proposal for methodologic guidelines

Pharmacogenetic studies in mood disorders are rapidly proliferating after the initial reports linking gene variants to treatment outcomes. However, a considerable range of methodologies has been used, making it difficult to compare results across studies and limiting the representativeness of findings. Specification of sampling source (inpatients vs outpatients, primary vs tertiary settings), standardization of diagnostic systems and treatments, adequate monitoring of compliance through plasma levels, sufficient length of observation (at least 6 weeks for acute antidepressant treatments, though 3-6 months are preferable), the use of a range of response criteria and the inclusion of possible environmental confounding variables (life events, social support, temperament) are all potentially important issues when planning pharmacogenetic studies. We reviewed the state-of-the-art methodology and suggested possible guideline for future studies.