Affective temperaments are associated with the white matter microstructure in healthy participants

Association between irritable temperament and glucose metabolism in the left insula and the right cerebellum

INTRODUCTION

Affective temperaments are assumed to have biological and neural bases. In the present study, we analyzed 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) images of healthy participants to explore the neural basis of affective temperaments.

METHOD

We utilized data of affective temperament measured by the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego-Autoquestionnaire and 18F-FDG PET images of healthy participants from two of our previous studies. A multiple regression analysis was performed to assess the association between 18F-FDG uptake and temperament scores using Statistical Parametric Mapping 12.

RESULTS

The final sample included 62 healthy participants. Whole-brain analysis revealed a cluster of 18F-FDG uptake that was significantly and positively associated with irritable temperament scores in the right cerebellum (Crus II, VIII, and IX). After further adjustment for the other four temperament scores, whole-brain analysis revealed a cluster of 18F-FDG uptake significantly and positively associated with irritable temperament scores in the left insula and right cerebellum (Crus II, VIII, and IX). However, no significant association was found between 18F-FDG uptake and the other four temperaments (depressive, cyclothymic, hyperthymic, and anxious).

CONCLUSIONS

The left insula and right cerebellum of the cerebrocerebellar circuit may be one of the neural bases of irritable temperament.

Neural substrates of affective temperaments: An intersubject representational similarity analysis to resting-state functional magnetic resonance imaging in nonclinical subjects

Previous research has suggested that certain types of the affective temperament, including depressive, cyclothymic, hyperthymic, irritable, and anxious, are subclinical manifestations and precursors of mental disorders. However, the neural mechanisms that underlie these temperaments are not fully understood. The aim of this study was to identify the brain regions associated with different affective temperaments. We collected the resting-state functional magnetic resonance imaging (fMRI) data from 211 healthy adults and evaluated their affective temperaments using the Temperament Evaluation of Memphis, Pisa, Paris and San Diego Autoquestionnaire. We used intersubject representational similarity analysis to identify brain regions associated with each affective temperament. Brain regions associated with each affective temperament were detected. These regions included the prefrontal cortex, anterior cingulate cortex (ACC), precuneus, amygdala, thalami, hippocampus, and visual areas. The ACC, lingual gyri, and precuneus showed similar activity across several affective temperaments. The similarity in related brain regions was high among the cyclothymic, irritable, and anxious temperaments, and low between hyperthymic and the other affective temperaments. These findings may advance our understanding of the neural mechanisms underlying affective temperaments and their potential relationship to mental disorders and may have potential implications for personalized treatment strategies for mood disorders.

Covariation between spontaneous neural activity in the insula and affective temperaments is related to sleep disturbance in individuals with major depressive disorder

BACKGROUND

Affective temperaments have been considered antecedents of major depressive disorder (MDD). However, little is known about how the covariation between alterations in brain activity and distinct affective temperaments work collaboratively to contribute to MDD. Here, we focus on the insular cortex, a critical hub for the integration of subjective feelings, emotions, and motivations, to examine the neural correlates of affective temperaments and their relationship to depressive symptom dimensions.

METHODS

Twenty-nine medication-free patients with MDD and 58 healthy controls underwent magnetic resonance imaging scanning and completed the Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS). Patients also received assessments of the Hamilton Depression Rating Scale (HDRS). We used multivariate analyses of partial least squares regression and partial correlation analyses to explore the associations among the insular activity, affective temperaments, and depressive symptom dimensions.

RESULTS

A profile (linear combination) of increased fractional amplitude of low-frequency fluctuations (fALFF) of the anterior insular subregions (left dorsal agranular-dysgranular insula and right ventral agranuar insula) was positively associated with an affective-temperament (depressive, irritable, anxious, and less hyperthymic) profile. The covariation between the insula-fALFF profile and the affective-temperament profile was significantly correlated with the sleep disturbance dimension (especially the middle and late insomnia scores) in the medication-free MDD patients.

CONCLUSIONS

The resting-state spontaneous activity of the anterior insula and affective temperaments collaboratively contribute to sleep disturbances in medication-free MDD patients. The approach used in this study provides a practical way to explore the relationship of multivariate measures in investigating the etiology of mental disorders.

Cortical myelin content mediates differences in affective temperaments

BACKGROUND

Affective temperaments are regarded as subclinical forms and precursors of mental disorders. It may serve as candidates to facilitate the diagnosis and prediction of mental disorders. Cortical myelination likely characterizes the neurodevelopment and the evolution of cognitive functions and reflects brain functional demand. However, little is known about the relationship between affective temperaments and myelin plasticity. This study aims to analyze the association between the affective temperaments and cortical myelin content (CMC) in human brain.

METHODS

We measured affective temperaments using the Temperament Evaluation of Memphis, Pisa, Paris and San Diego Autoquestionnaire (TEMPS-A) on 106 healthy adults and used the ratio of T1- and T2-weighted images as the proxy for CMC. Using the unsupervised k-means clustering algorithm, we classified the cortical gray matter into heavily, intermediately, and lightly myelinated regions. The correlation between affective temperaments and CMC was calculated separately for different myelinated regions.

RESULTS

Hyperthymic temperament correlated negatively with CMC in the heavily myelinated (right postcentral gyrus and bilateral precentral gyrus) and lightly myelinated (bilateral frontal and lateral temporal) regions. Cyclothymic temperament showed a downward parabola-like correlation with CMC across the heavily, intermediately, and lightly myel0inated areas of the bilateral parietal-temporal regions.

LIMITATIONS

The analysis was constrained to cortical regions. The results were obtained from healthy subjects and we did not acquired data from patients of affective disorder, which may compromise the generalizability of the present findings.

CONCLUSION

The findings suggest that hyperthymic and cyclothymic temperaments have a CMC basis in extensive brain regions.

Exploring the Effects of Temperament on Gray Matter Volume of Frontal Cortex in Patients with Mood Disorders

BACKGROUND

Patients with bipolar disorder (BD) and patients with major depressive disorder (MDD) have relatively specific temperament and structural abnormalities of brain regions related to emotion and cognition. However, the effects of temperament factors on the structure of frontal and temporal cortex is still unclear. The aims of this study were to explore the differences and relationships between temperament characteristics and the gray matter volume of frontal and temporal cortex in patients with BD or MDD.

METHODS

T1-weighted magnetic resonance imaging (MRI) data, demographic and clinical information were obtained from 279 depressed patients (90 patients with BD, 189 patients with MDD) and 162 healthy controls (HC). Temperament was assessed with the Chinese short version of Temperament Evaluation of Memphis, Pisa and San Diego - Auto questionnaire (TEMPS-A). The Desikan-Killiany atlas was used for yielding gray matter volume by FreeSurfer 6.0 software suite. A total of 22 frontal and temporal regions were chosen as regions of interest (ROIs).

RESULTS

Compared with patients with MDD, patients with BD had higher TEMPS-A total scores and scores on cyclothymic, irritable and hyperthymic subscales. The gray matter volume in bilateral rostral middle frontal gyrus (RMFG), left temporal pole and right superior frontal gyrus were reduced in patients with BD. Patients with MDD only had lower gray matter volume in bilateral temporal pole. In the pooled patients, there were negative associations between hyperthymia and gray matter volume in right RMFG.

CONCLUSION

Patients with BD and MDD had different temperament characteristics. The prominent temperament subscales in patients with BD were cyclothymia, irritable and hyperthymia. Patients with greater hyperthymia had lower gray matter volume in right frontal gyrus. Temperament may reflect an endophenotype in patients with mood disorders, especially in BD.