Alexithymia linked to white matter integrity in schizophrenia

By Mark Cowen, medwireNews Reporter

Increased levels of alexithymia among patients with schizophrenia are associated with reductions in white matter integrity in specific regions of the corpus callosum, researchers report.

"The results indicate the existence of white matter pathology possibly underlying impaired emotional self-awareness in schizophrenia," say Jun Miyata (Kyoto University, Japan) and colleagues.

The findings come from a study of 44 patients (26 men) with schizophrenia, aged a mean of 36.6 years, and 44 age-, gender- and predicted IQ level-matched mentally healthy individuals (controls).

All of the participants were evaluated for emotional self-awareness using the 20-item Toronto Alexithymia Scale (TAS-20), which assesses difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking.

They also underwent diffusion-weighted imaging of the brain, and differences in white matter fractional anisotropy (FA) values were compared with scores on the TAS-20.

Overall, patients with schizophrenia scored significantly higher than controls on the TAS-20, at 57.34 versus 45.09, indicating greater impairments in emotional self-awareness.

Patients with schizophrenia also exhibited significant white matter FA reductions compared with controls in a cluster involving the frontal, temporal, parietal and occipital lobes, a large portion of the corpus callosum, and the corona radiata.

In patients with schizophrenia, TAS-20 scores were negatively correlated with white matter FA values in the splenium and the corpus callosum; mostly the left part of the superior longitudinal fasciculus, the inferior longitudinal fasciculus, the inferior fronto-occipital fasciculus, and the posterior thalamic radiation.

No such correlations were observed in controls, the researchers note.

"In conclusion, the present study suggested an association between alexithymia and schizophrenia," write Miyata et al in Schizophrenia Research.

They add: "Our results suggest that these white matter regions might be an important underlying pathology of impaired emotional self-awareness in schizophrenia, sharing the neural bases with interhemispheric transfer deficits and impaired cognitive domains, including language processing, social cognition, and self-related processing in this disease."

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