The Impairment Of Executive Function Under Non-emotional And Emotional Context In Alexithymic Individuals:Evidence From Behavioral And Electrophysiological Study

Objective Alexithymia, characterized by difficulties in identifying and describing feelings, is highly indicative of a broad range of psychiatric disorders. Several studies have also discovered the response inhibition ability impairment in alexithymia. However, few studies on alexithymic individuals have specifically examined how emotional context modulates response inhibition procedure. Utilizing the neuropsychological tests, we investigated whether alexithymia is related to or independent of executive function, especially with respect to response inhibition. In order to investigate emotion cognition interaction in alexithymia, we analyzed the spatiao-temporal features of such emotional response inhibition by the approaches of event-related potentials and neural source-localization.Methods Four hundred students from Anhui Medical University were screened for alexithymia using the Chinese version of the Toronto Alexithymia Scale (TAS-20). The participants who scored higher than59were in alexithymic group, and who scored lower than41were in control group. All participants also met the following exclusion criteria:(a) no current substance (including alcohol) abuse.(b) no depressive disorder or anxiety disorder.(scores of the Self-Rating Depression Scale (SDS) of≤41, and scores of the Self-Rating Anxiety Scale (SAS)<40);(c) no demonstrable brain disease (such as epilepsy, schizophrenia, brain injury, or head trauma); The final sample included33students who scored higher than59in alexithymic group and30students who scored lower than41in control group. The participants were instructed to perform some neuropsychological tests (including Stroop test, Digital Span and Digital Sign tests and attention network test) and a modified emotional Go/Nogo task while their continuous electroencephalography activities were synchronously recorded. Results1、Results of neuropsychological tests:There were no significant group differences on the number of items completed under the color condition{t=-0.87, P>0.05) or the color-word condition (t=0.34, P>0.05). However, alexithymic individuals experienced greater interference as indicated by their total interference score (t=2.83, P <0.01), and were significantly slower in interference effect on RT (t=3.75, P<0.001). In addition, the scores of alexithymic individuals were more lower than scores of controls in Digital Span (t=-2.81, P=0.008);(t=-4.71, P<0.001) and Digital Sign tests(t=-2.26, P<0.05). In ANT, the alexithymic group had similar overall RT (t=0.532, P=0.601), and accuracy (t=0.345, P=0.738), as the control group. The alexithymic group had greater conflict scores, indicating that these individuals took longer to resolve conflict and had less efficient executive attention than normal controls (t=2.568, P=0.01). The differences between groups for alerting and orienting network scores were not significant (t=-0.42, t=1.448respectively, P>0.05).2、Results of ERP:The P3amplitudes of the Nogo-Go difference wave only in response to negative context was much larger for the alexithymic group than for the control group [F(1,29)=4.47, P<0.05]. Significant sources relating to the Nogo-P3are located in the ACC (x=-5, y=20, z=20; BA24/32) and showed significantly greater activation during response inhibition (Nogo conditions) than during response execution (Go conditions).Conclusion These results suggest that, alexithymic individuals had impairment in executive function, especially in response inhibition. Morever, our result provides further evidence at the neural level, that difficulty in identifying feelings is a major feature of alexithymia, particularly in negative emotion. Furthermore, our findings supported that anterior cingulate cortex (ACC) plays a critical role in emotion-modulated response inhibition related to alexithymia.