Mixed emotions: the contribution of alexithymia to the emotional symptoms of autism

Abstract

It is widely accepted that autism is associated with disordered emotion processing and, in particular, with deficits of emotional reciprocity such as impaired emotion recognition and reduced empathy. However, a close examination of the literature reveals wide heterogeneity within the autistic population with respect to emotional competence. Here we argue that, where observed, emotional impairments are due to alexithymia-a condition that frequently co-occurs with autism-rather than a feature of autism per se. Alexithymia is a condition characterized by a reduced ability to identify and describe one's own emotion, but which results in reduced empathy and an impaired ability to recognize the emotions of others. We briefly review studies of emotion processing in alexithymia, and in autism, before describing a recent series of studies directly testing this 'alexithymia hypothesis'. If found to be correct, the alexithymia hypothesis has wide-reaching implications for the study of autism, and how we might best support subgroups of autistic individuals with, and without, accompanying alexithymia. Finally, we note the presence of elevated rates of alexithymia, and inconsistent reports of emotional impairments, in eating disorders, schizophrenia, substance abuse, Parkinson's Disease, multiple sclerosis and anxiety disorders. We speculate that examining the contribution of alexithymia to the emotional symptoms of these disorders may bear fruit in the same way that it is starting to do in autism.

Figure 1

(Top panel) Illustration of the alexithymia hypothesis. Samples drawn from the autistic population may contain a high proportion of individuals with co-occurring alexithymia (for example, sample A), in which case the majority of tested individuals will exhibit emotional symptoms such as difficulties in recognizing others' emotions and reduced empathy. Samples may also contain relatively few individuals with co-occurring alexithymia (for example, sample C) yielding little evidence of emotional impairment in the majority of individuals tested, leading to the conclusion that autism is not characterized by emotional symptoms. More typically, however, samples drawn from the autistic population are likely to be heterogeneous; comprising a mix of individuals with varying degrees of co-occurring alexithymia (for example, sample B), leading to weak inconsistent trends toward emotional deficits across studies and wide heterogeneity within experimental samples. (Bottom panel) Representative data from Cook et al. demonstrating that increasing degrees of alexithymia is associated with increased attribution thresholds (indicative of poor emotion recognition) for emotional facial expressions. After accounting for alexithymia there was no effect of autism.