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

OBJECTIVES: Five affective temperaments are regarded as potential precursors of bipolar disorder. These are depressive, cyclothymic, hyperthymic, irritable, and anxious temperaments. However, the neural substrates underlying these temperaments have not been identified. The aim of this study was to determine whether these temperaments are associated with specific neural substrates related to the brain white matter integrity in healthy participants. METHODS: We conducted a cross-sectional neuroimaging study of 71 healthy participants (38 males and 33 females) with affective temperaments. All participants screened for past and present psychiatric disorders. The scores of the five affective temperaments were measured by the temperament scale of Memphis, Pisa, Paris, and San Diego-autoquestionnaire. We analyzed the association between the fractional anisotropy (FA) and mean diffusivity (MD) of the brain white matter and these affective temperaments using tract-based spatial statistics (TBSS). RESULTS: The cyclothymic temperament score had a significant positive association with the FA and a significant negative association with the MD in the white matter in the right frontal part of brain. The hyperthymic temperament score was negatively associated with the MD in a wide area of the brain white matter. The anxious temperament score was positively associated with the FA in the bilateral frontal, temporal, and parietal regions of the brain white matter. The depressive and irritable temperament scores were not associated with either the FA or the MD. CONCLUSION: The present findings suggest that cyclothymic, hyperthymic, and anxious temperaments are associated with brain white matter integrity in healthy participants.

Low risk of male suicide and lithium in drinking water.

OBJECTIVE: Recently, several epidemiologic studies reported that lithium in drinking water may be associated with lower rates of suicide mortality at the population level, but other studies failed to confirm the association. The objective of the present study is to determine whether lithium in drinking water is associated with lower suicide rate after adjustment of potential confounding factors. METHOD: From 2010 to 2013, 274 mean lithium levels of 434 lithium samples in drinking water were examined in relation to suicide standardized mortality ratios (SMRs) in 274 municipalities of Kyushu Island in Japan. Weighted least squares regression analysis adjusted for the size of each population was used to investigate the association of lithium levels with suicide SMRs. The associations of lithium levels in drinking water with suicide SMRs (total, male, and female) were investigated adjusting for proportion of elderly people, proportion of 1-person households, proportion of people with college education or more, and proportion of people engaging in primary industry (adjusted model 1), and further adjustment was performed with overall unemployment rate, annual marriage rate, annual mean temperature, and annual postal savings per person (adjusted model 2). RESULTS: Lithium levels in drinking water were significantly (ß = -.169, P = .019) and inversely associated with male suicide SMRs but not total or female SMRs in the adjusted model 2. CONCLUSIONS: The present findings suggest that lithium in drinking water may be associated with the low risk of male suicide in the general population. Further studies are required to confirm these findings and investigate gender differences.

Identification of the neural correlates of cyclothymic temperament using a working memory task in fMRI.

BACKGROUND: Recently, we reported a significantly negative association of cyclothymic temperament scores with activations of the left lingual gyrus during esthetic judgments of paintings, suggesting that cyclothymic temperament may be associated with the left lingual gyrus. In view of potential associations of cyclothymic temperament, bipolar disorder and dementia, this study examined the relationship of temperament to lingual gyrus activity using a working memory task as a new context. METHODS: N-back tasks (0-, 1-, 2- and 3-back tasks) were performed on 34 healthy subjects using functional MRI. Multiple regression analyses were applied to measure the association between cyclothymic temperament scores and each of 4 beta images corresponding to 0-, 1-, 2- and 3-back tasks with gender, age and the other temperament scores (depressive, hyperthymic, irritable and anxious) as covariates. RESULTS: The whole brain analysis corrected for multiple comparisons revealed a significant activation of the left lingual gyrus associated with cyclothymic temperament scores in a new context-working memory for both 2- and 3-back tasks. LIMITATIONS: The number of subjects was relatively small. The subjects were almost medical staff or students and the results should be interpreted with caution. CONCLUSIONS: The present findings reconfirm that cyclothymic temperament may be associated with the left lingual gyrus.

Identification of the neural correlates of cyclothymic temperament using an esthetic judgment for paintings task in fMRI.

BACKGROUND: There is a well-known association between artistic creativity and cyclothymic temperament but the neural correlates of cyclothymic temperament have not yet been fully identified. Recently, we showed that the left lingual gyrus and bilateral cuneus may be associated with esthetic judgment of representational paintings, we therefore sought to investigate brain activity during esthetic judgment of paintings in relation to measures of cyclothymic temperament. METHODS: Regions of interest (ROI) were set at the left lingual gyrus and bilateral cuneus using automated anatomical labeling, and percent signal changes of the ROIs were measured by marsbar toolbox. The associations between percent signal changes of the ROIs during esthetic judgments of paintings and cyclothymic temperament scores were investigated by Pearson׳s coefficient. Moreover, the associations were further analyzed using multiple regression analysis whereby cyclothymic temperament scores were a dependent factor and percent signal changes of the 3 ROIs and the other 4 temperament scores were independent factors. RESULTS: There was a significantly negative association of cyclothymic temperament scores with the percent signal changes of the left lingual gyrus during esthetic judgments of paintings, but not with those of bilateral cuneus. Even after adjustment using multiple regression analysis, this finding remained unchanged. LIMITATIONS: The number of subjects was relatively small and the task was limited to appreciation of paintings. CONCLUSIONS: The present findings suggest that cyclothymic temperament may be associated with the left lingual gyrus.

Difference in brain activations during appreciating paintings and photographic analogs.

Several studies have investigated neural correlates of aesthetic appreciation for paintings but to date the findings have been heterogeneous. This heterogeneity may be attributed to previous studies' measurement of aesthetic appreciation of not only the beauty of paintings but also the beauty of motifs of the paintings. In order to better elucidate the beauty of paintings, it seems necessary to compare aesthetic appreciation of paintings and photographic analogs which included corresponding real images. We prepared for famous painters' pictures and their photographic analogs which were set up to resemble each painting in order to investigate the hypothesis that there exist specific neural correlates associated with the aesthetic appreciation for paintings. Forty-four subjects participated in functional magnetic resonance study which required comparisons of aesthetic appreciation of paintings of still life and landscape versus photographic analogs including corresponding real images of still life and landscape. Bilateral cuneus and the left lingual gyrus were activated in the comparison of aesthetic appreciation of paintings versus photographic analogs. In conclusion, the present findings suggest a possibility of the existence of specific neural correlates associated with the aesthetic appreciation for paintings and that bilateral cuneus and the left lingual gyrus may be involved.