Neuro-cognitive correlates of alexithymia in patients with circumscribed prefrontal cortex damage

Alexithymia has been extensively reported in studies of psychiatric patients. However, little attention has been paid regarding its occurrence in the context of patients with circumscribed prefrontal cortex lesions. Moreover, the neuro-cognitive impairments that lead to alexithymia remain unclear and limited numbers of studies have addressed these issues. The authors investigated the impact of prefrontal cortex lesions on alexithymia and its neuro-cognitive correlates in a population of 20 patients with focal frontal lesions, 10 patients with parietal lesions and 34 matched control participants. Alexithymia was screened using the Toronto Alexithymia Scale (TAS-20) and executive functions were assessed using a large battery of executive tasks that address inhibition, flexibility and the planning process. Results showed that patients with prefrontal cortex damage showed significantly increased difficulty in facets of identifying feelings (DIF) and externally oriented thinking (EOT) on TAS-20, compared to parietal patients and control participants. Moreover, both correlation and regression analysis revealed that higher alexithymia levels on the three facets of TAS-20 were consistently but differentially associated with impairment in inhibition, flexibility and planning tasks for frontal patients and both control groups. These findings provide clinical evidence of the implication of prefrontal cortex damage and executive control in alexithymia. Our results were also discussed in the light of the cognitive appraisal concept as a mechanism involved in emotion episode processing. This study suggests that increased neuropsychological attention should be directed to the relation between the neuro-cognitive model of executive functions and cognitive appraisal theory in processing emotion.