Alexithymia and brain gray matter volumes in a general population sample

Abstract

Alexithymia is perceived as a personality construct involving deficits in the cognitive processing of emotion. Brain areas that process emotions might be structurally altered in affected people. Subjects from the Study of Health in Pomerania who underwent whole body magnetic resonance imaging were investigated. After quality control procedures 2,589 subjects with Toronto Alexithymia Scale 20 (TAS-20) data and interview-based information on major depressive disorder (MDD) were available. After exclusion of study participants who were older than 65 years or had MDD in their lifetime, 1,685 subjects were included in the voxel-based morphometric (VBM 8) analyses. In whole-brain analyses, the TAS-20 total score was associated with less gray matter (GM) volumes of the bilateral dorsal anterior cingulate cortex (dACC). The TAS-20 factor scale difficulty identifying feelings (DIF) was associated with less GM volume in three clusters: dACC, left middle and inferior temporal gyrus, left fusiform gyrus and cerebellum. The lower GM volume in the left fusiform gyrus was specific for females. Absolute GM volume analyses also revealed associations between the factor scales difficulty describing feelings, external orientated thinking and the dACC. Adjustment for current symptoms of anxiety and depression did not change the effects sizes substantially. In conclusion, lower GM volume in the dACC represents the major structural correlate of alexithymia. Associations with DIF suggest a prominent involvement of left temporal areas. These areas represent language and semantic processing and might be involved in the cognitive processing of emotions and the conscious identification of feelings.

Neuroanatomical profiles of alexithymia dimensions and subtypes

“…Similarly, previous studies reported either smaller [Borsci et al, ; Grabe et al, ; Ihme et al, ] or larger [Zhang et al, ] volumes of the insula, whereas others did not observe alexithymia‐related differences in this structure [Heinzel et al, ; Kubota et al, ; Sturm and Levenson, ]. Smaller amygdala volume was observed in two studies [Grabe et al, ; Ihme et al, ], while others failed to find differences in amygdala volume [Borsci et al, ; Heinzel et al, ; Kubota et al, ].…”

“…Kugel et al reported a negative correlation between TAS‐20 (i.e., cognitive) alexithymia scores and amygdala reactivity to masked emotional faces [Kugel et al, ], a finding that was replicated by Reker et al, who used the same paradigm and additionally observed reduced automatic activation of the insula [Reker et al, ]. Although not identified in all studies [e.g., Heinzel et al, ; van der Velde et al, ], both the amygdalae and the insulae have indeed been found to differ in volume as a function of alexithymia by previous VBM studies employing the TAS‐20 scale (and thus assessing the cognitive alexithymia dimension): Ihme et al reported reduced left amygdala ROI volume in 17 high‐ compared to 17 low‐scorers on alexithymia [Ihme et al, ], a finding that was confirmed by a recently published large‐scale study, which reported reduced gray matter volumes in the right amygdala and the left insula in 844 male participants [Grabe et al, ]. Moreover, several studies reported differences in insula volume in relation to high levels of alexithymia [Borsci et al, ; Goerlich‐Dobre et al, ; Ihme et al, ; Zhang et al, ].…”

“…Reduced white matter volume [Habib and Joly‐Pottuz, ] and integrity [Kubota et al, ] of the corpus callosum were reported in alexithymic patients with multiple sclerosis and schizophrenia, respectively, whereas no corpus callosum differences were found in a healthy control group in relation to alexithymia [Kubota et al, ]. Using surface area measurements, the ACC was found to be larger in surface in individuals scoring high on alexithymia [Gundel et al, ], whereas other studies using automated voxel‐based morphometry (VBM) observed smaller gray matter volumes of the ACC [Borsci et al, ; Grabe et al, ; Ihme et al, ; Koven et al, ; Paradiso et al, ; Sturm and Levenson, ], or no association between alexithymia and ACC volume [Heinzel et al, ]. Similarly, previous studies reported either smaller [Borsci et al, ; Grabe et al, ; Ihme et al, ] or larger [Zhang et al, ] volumes of the insula, whereas others did not observe alexithymia‐related differences in this structure [Heinzel et al, ; Kubota et al, ; Sturm and Levenson, ].…”

“…Using surface area measurements, the ACC was found to be larger in surface in individuals scoring high on alexithymia [Gundel et al, ], whereas other studies using automated voxel‐based morphometry (VBM) observed smaller gray matter volumes of the ACC [Borsci et al, ; Grabe et al, ; Ihme et al, ; Koven et al, ; Paradiso et al, ; Sturm and Levenson, ], or no association between alexithymia and ACC volume [Heinzel et al, ]. Similarly, previous studies reported either smaller [Borsci et al, ; Grabe et al, ; Ihme et al, ] or larger [Zhang et al, ] volumes of the insula, whereas others did not observe alexithymia‐related differences in this structure [Heinzel et al, ; Kubota et al, ; Sturm and Levenson, ]. Smaller amygdala volume was observed in two studies [Grabe et al, ; Ihme et al, ], while others failed to find differences in amygdala volume [Borsci et al, ; Heinzel et al, ; Kubota et al, ].…”

Tai Chi Chuan and Baduanjin Increase Grey Matter Volume in Older Adults: A Brain Imaging Study

“…The template was then used to normalize the images into the standard Montreal Neurological Institute (MNI) space using the “DARTEL Normalize to MNI Space” program, utilizing the “preserve amount” option to retain the volumetric data of the original images. Finally, spatial smoothing was performed with an isotropic Gaussian kernel of 8mm full-width at half maximum [59,60]. …”