Alexithymia in healthy women: a brain morphology study

Alexithymia relates to difficulty recognizing and describing own feelings. Recent literature shows that specific structures process emotions. Aim of this study was to investigate whether alexithymia is associated with a specific cerebral morphology of candidate structures in healthy adults.

Fifty-four female volunteers were enrolled in the study and the 20-item Toronto Alexithymia Scale (TAS-20) was self-administered. Gray matter (GM) volume was assessed with an optimized voxel-based morphometry (VBM) protocol on high-resolution 3D magnetic resonance images. The following three experiments were carried out: 1) contrast between the 14 volunteers with TAS-20 scores > or = 61 (alexithymic) and the 30 with scores < 51 (non-alexithymic), 2) correlation of TAS-20 scores on the whole sample and 3) contrast between the 14 alexithymic and 14 non-alexithymic matched by age. The significant threshold for VBM comparisons and correlation was set at p<0.005 uncorrected.

The alexithymic group showed smaller GM volume in the anterior cingulate cortex (cluster size: 735 voxel no.; z=3.26; stereotaxic coordinates: -12, 22, 30) and middle temporal gyrus (256; 3.21; -60, 2, -20). Of specific biological relevance, smaller clusters were located in the anterior insula, orbitofrontal cortex and superior temporal sulcus. The opposite comparison was negative. The correlation analysis confirmed the pattern of results mainly in the left hemisphere.

Our findings suggest that the ability to process emotional aspects of the self correlates with morphology of a specific set of cerebral structures known to be involved in decision making and self awareness and rich in neurons subserving social competence.