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

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.

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).

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.

The present findings suggest that cyclothymic, hyperthymic, and anxious temperaments are associated with brain white matter integrity in healthy participants.