Emotion processing and autism spectrum disorder: A review of the relative contributions of alexithymia and verbal IQ

Background: People with autism spectrum disorder (ASD) have a unique way of navigating the social world around them, including processing emotions. Discrepancies in emotion processing between persons with ASD as compared to typically developing individuals have been attributed to lower levels of verbal intelligence or the co-occurrence of alexithymia, a personality trait defined as a specific difficulty in identifying and expressing emotions. The purpose of this paper was to systematically review and summarize the literature on alexithymia, while accounting for verbal intelligence, in relation to the emotion processing of people with ASD. Method: Of the 309 identified empirical papers, 13 were eligible for inclusion in this review. Information was compiled on performance on emotion processing tasks, measures of alexithymia, verbal IQ, and ASD symptom severity, as well as age range, sex, and type of study (e.g., beha-vioural, neuroimaging). Results: The majority of studies included adults with average to above average verbal IQ. Overall, the findings from the 13 studies represent preliminary evidence that verbal IQ has a strong in-fluence on performance on behavioural emotion processing tasks, while alexithymia influences physiological and brain responses to emotion tasks. Conclusions: Both verbal IQ and alexithymia play an important and potentially distinct role in explaining how people with ASD process emotions at a behavioural and physiological level.