Clarifying the relationship between alexithymia and subjective interoception

Abstract

The long-standing hypothesis that emotions rely on bodily states is back in the spotlight. This has led some researchers to suggest that alexithymia, a personality construct characterized by altered emotional awareness, reflects a general deficit in interoception. However, tests of this hypothesis have relied on heterogeneous assessment methods, leading to inconsistent results. To shed some light on this issue, we administered a battery of self-report questionnaires of interoception and alexithymia to three samples from Italy, the U.S., and Singapore (N = 814). Correlation and machine learning analyses showed that alexithymia was associated with deficits in both subjective interoceptive accuracy and attention. Alexithymics’ interoceptive deficits were primarily related to difficulty identifying and describing feelings. Interoception showed a weaker association with externally-oriented thinking as operationalized by the Toronto Alexithymia Scale (TAS-20) and no association with the affective dimension of alexithymia later introduced by the Bermond-Vorst Alexithymia Questionnaire (BVAQ). We discuss our results with reference to the theoretical and psychometric differences between these two measures of alexithymia and their shortcomings. Overall, our results support the view that interoceptive deficits are a core component of alexithymia, although the latter cannot be reduced to the former.

Shared and unique interoceptive deficits in high alexithymia and neuroticism

“…The data collection for the current study was part of a broader data collection, involving additional psychological tests. The findings related to the other parts of the project are reported in a separate paper [ 31 ]. The protocols of this project were approved by the Nanyang Technological University of Singapore (PSY-IRB 2019–030; IRB 2020-10-016).…”

“…There is evidence that high alexithymic traits also occur in the non-clinical population; an incidence between 9 and 13% has been reported in Western countries [ 29 , 30 ]. In non-clinical populations, alexithymic traits were found to be associated with lowered self-reported interoceptive accuracy [ 12 , 31 ] and interoceptive awareness [ 32 ].…”

“…However, the degree of this association is still debated. Some researchers characterize alexithymia as a general failure of interoception [ 33 ], while others adopt a more cautious position [ 31 , 34 ]. The latter position is largely based on methodological considerations, especially uncertainties concerning how to best measure interoception across different dimensions (i.e.…”

“…New behavioural tasks for measuring Interoceptive Accuracy (IAcc) are urgently needed given that the widely used Heartbeat Counting Task (HCT) sometimes produces contradictory findings which, overall, do not support the association between IAcc and alexithymia [ 12 , 35 ]. Despite such concerns, the negative association between alexithymia and self-reported interoceptive ability (IS) is statistically well supported [ 12 , 31 ].…”

“…Yet, there are at least two theoretical issues that also suggest caution in inferring a strong relationship between alexithymia and interoception. Firstly, while atypical interoceptive awareness is certainly a characteristic of alexithymia, it might be possible that not all aspects of this condition are directly related to it [ 31 , 34 ]. For example, two of the three subscales of the TAS-20 are quite closely related to atypical interoception (DIF and DDF), while the third (EOT) may instead reveal disrupted cognitive processing of the emotional signal.…”