Higher scores in the extraversion personality trait are associated with a functional polymorphism in the PER3 gene in healthy subjects

Chronotypes-personality behavioural syndromes in wild marine fish

Chronotypes, the individual differences in daily activity timing, have profound associations with numerous physiological processes. Despite this, the covariance between chronotypes and other aspects of an individual's behaviour has been infrequently explored in non-human animals. This study delves into individual's variation across four axes of personality in a controlled environment, utilising the pearly razorfish, a model species for fish chronotype studies. We identified behavioural types across the aggressiveness continuum and established behavioural syndromes amongst exploration, activity, and boldness, irrespective of body size and condition. Subsequent to this, the experimental subjects were reintroduced to their natural habitat and individually tracked using high-resolution technology to ascertain their chronotypes. Our results revealed that whilst the exploration-activity-boldness syndrome bore no correlation with chronotypes, a significant association was observed between aggressiveness and chronotype. Hence, individuals with later awakening times and rest onsets were more aggressive than their counterparts with earlier awakening times and rest onsets. This study provides pioneering evidence linking fish chronotypes with other behavioural traits, such as aggressiveness, suggesting that behavioural variation could be potentially linked to the individuals' variation in internal clocks and the environmental variables influencing their expression.

The associations of chronotype and social jetlag with prosocial behavior problems among Chinese adolescents

Potential relevance between the circadian rhythm and behavioral health has got raising attention in recent years. This study aimed to examine chronotype, social jetlag and their associations with prosocial behavior problems among Chinese adolescents. A total of 4,666 middle school students aged 12-18 years were enrolled in study. Sleep characteristics were collected by the modified Chinese version of Adolescent Sleep Hygiene Scale (M-ASHS); MSFsc and mid-sleep point were calculated to determine chronotypes and social jetlag. Prosocial behavior problems were assessed by the Strength and Difficult Questionnaire (SDQ). Multivariate logistic regression was applied to analyze the relationships between chronotype and social jetlag with prosocial behavior problems. Evening chronotype was associated with higher risk of prosocial behavior problems, whether among male (OR = 1.82, 95%CI:1.27-2.61, P = .001) or female adolescents (OR = 1.83, 95%CI:1.15-2.91, P = .011). Female adolescents with social jetlag of 1-2 hours had 1.60 times the risk of prosocial behavior problems than their peers whose social jetlag was <1 h (P = .028); social jetlag ≥ 2 h was positively associated with prosocial behavior problems in both male and female adolescents (OR = 1.79 and 2.45, respectively, both P < .05). Further, the combination of intermediate chronotype and social jetlag ≥ 2 h was correlated with prosocial behavior problems only in female adolescents (OR = 3.24, 95%CI = 1.40-9.21, P = .004). Evening chronotype and higher social jetlag were risk factors for prosocial behavior problems in adolescents, especially for the female. For the promotion of prosocial behavior in adolescents, the importance of circadian rhythm should be addressed.

Time-of-day effects on objective and subjective short-term memory task performance

The time-of-day along with the synchrony effect (better performance at optimal times of the day according to the chronotype) on the cognitive performance has been well established in previous research. This influence is mediated by both circadian and homeostatic processes consistent with the Borbély two-process model. This experiment focused on the objective and subjective performance of the visual short-term memory task requiring holistic processing. Sixty-five young, healthy participants including 40 females were divided into morning and evening types and performed a given task in two sessions - in the morning and in the evening. Type division was made according to the chronotype questionnaire and polymorphism of the PER3 clock gene. The task was a modified version of Deese-Roediger-McDermott paradigm adjusted to study short-term memory, in which visual, abstract stimuli were used. The analysis was based on an exploratory approach investigating the influence of circadian and individual (sex) factors on execution of memory task. Evening types were more accurate in the task compared to morning types, regardless of the part of the day. The time-of-day effect was revealed on objective measures (reaction times for hits and false alarms) and subjective effort put into the performance. The reaction times were slower in the morning unlike the effort that was greater in the evening. The time-of-day × sex interaction was observed in the case of subjective effort: men described the task as more demanding in the evening. The results could be explained by differences in hemispheric dominance depending on the time-of-day. The report provides new patterns of behavioral data analysis, investigating sex aspects and use of self-assessment scales of performance.

Personality traits relate to chronotype at both the phenotypic and genetic level

INTRODUCTION

Diurnal preferences have been linked to personality but often with mixed results. The present study examines the relationships between sleep timing (chronotype), diurnal preferences, and the Five-Factor Model of personality traits at the phenotypic and genetic level.

METHODS

Self- and informant-reports of the NEO Personality Inventory-3, self-reports of the Munich Chronotype Questionnaire, and DNA samples were available for 2,515 Estonian adults (M_age  = 45.76 years; 59% females). Genetic correlations were obtained through summary statistics of genome-wide association studies.

RESULTS

Results showed that higher Conscientiousness and lower Openness to Experience were significant predictors of earlier chronotype. At the level of facets, we found that more straightforward (A2) and excitement-seeking (E5), yet less self-disciplined (C5) people were more likely to have later chronotypes. The nuance-level Polypersonality score was correlated with chronotype at r = .28 (p < .001). Conscientiousness and Openness were genetically related with diurnal preferences. The polygenic score for morningness-eveningness significantly predicted the Polypersonality score.

CONCLUSION

Phenotypic measures of chronotype and personality showed significant associations at all three of levels of the personality hierarchy. Our findings indicate that the relationship between personality and morningness-eveningness is partly due to genetic factors. Future studies are necessary to further refine the relationship.

Association Between a Functional Polymorphism in the Monoamine Oxidase A (MAOA) Gene and Both Emotional Coping Style and Neuroticism

Background:

Identification of novel genetic factors for Depressive Disorders (DD) represents a major challenge around the world. Molecular studies of endophenotypes associated with DD, such as personality traits and coping, are powerful strategies for finding genetic markers.

Objective:

The main objective of this work was to confirm the potential relationship between a functional polymorphism in the monoamine oxidase A (MAOA) gene and scores in coping and neuroticism in young adults.

Methods:

A Colombian sample of two hundred fifty-one young participants was evaluated with the short forms of the Coping Inventory for Stressful Situations (CISS-SF) and the Big Five Inventory (BFI-S). Genotypes for MAOA-VNTR polymorphism were obtained by PCR.

Results:

A significant relationship between the functional MAOA-VNTR polymorphism and scores in both emotion-oriented coping and neuroticism was found. Individuals carrying the 4 allele (3/4 or 4/4 genotypes) had higher scores for both emotion-oriented coping and neuroticism than individuals with a 3/3 genotype.

Conclusion:

Our current findings are novel in terms of being the first report of a relationship between a functional polymorphism in the MAOA gene and coping and add evidence to the association of this gene with neuroticism. Our results expand the associations between MAOA gene and multiple dimensions of human emotion and personality.