The Impact of Alexithymia on Autism Diagnostic Assessments

Background: Alexithymia, a difficulty identifying and communicating one’s own emotions, affects socio-emotional processes, such as emotion recognition and empathy. Indeed, research has highlighted several behavioural characteristics traditionally attributed to autism that have been demonstrated to be related to alexithymia. Given that many of these behaviours are assessed during autism assessments such as the Autism Diagnostic Observation Schedule (ADOS), it is pertinent to examine the relationship between alexithymia and scores on autism diagnostic assessments.

Objectives: Our objective was to examine the association between alexithymia and ADOS scores. We examined 1) the impact of alexithymia on meeting the criteria for autism/ASD, 2) correlations between alexithymia and ADOS subscales, and 3) whether alexithymia predicted scores on specific ADOS items, selected a priori based on the literature.

Methods: We utilised two previous datasets for which both ADOS and alexithymia data were available. Participants included 96 women with anorexia, and 147 adolescents who were either high in autistic symptoms, or whose twin had high autistic symptoms. Both samples of participants completed the Toronto Alexithymia Scale (TAS-20), a self-report alexithymia measure. For the adolescent sample, parent-report alexithymia scores were also available (the Observer Alexithymia Scale). Current depression/anxiety symptoms were also measured: for the anorexia sample this was via the Hospital Anxiety and Depression Scale or the Moods and Feelings Questionnaire (depending on participant age), and for the adolescent sample this was via the Strengths and Difficulties Questionnaire.

Results: In the adolescent group, parent-reported (but not self-reported) alexithymia predicted autism/ASD diagnosis, correlated with both social affect and restricted and repetitive interests sub-scales, and predicted scores on a priori selected ADOS items. Fewer associations were observed in the anorexic sample, and most associations were removed once depression/anxiety symptoms were controlled for. Nonetheless, the presence of alexithymia predicted a near fourfold increase in the likelihood of meeting diagnostic criteria for autism/ASD in this sample.

Conclusions: Alexithymia does appear to show an association to ADOS scores, at the level of meeting the diagnostic threshold, ADOS subscales, and scores on specific items. The reduced associations in the anorexia sample could have arisen for a number of reasons. This includes the high level of depression and anxiety in this group potentially impacting on self-report alexithymia measures. Alternatively, this could be related to the gender and age of this group, as compared to the mostly male and younger adolescent group. This and future research have important implications for diagnostic practices, but also research practices in which ADOS assessments are considered the gold standard for inclusion in autism research.