Characterizing the Nature of Alexithymia in Autistic Adults: Validation of the Perth Alexithymia Questionnaire

Abstract

Background:

Alexithymia—a trait characterized by difficulties in emotion processing—is of high interest in the autism field. However, the lack of validated alexithymia measures for autistic individuals limits progress. This study aimed to address this gap by examining the psychometric properties of the Perth Alexithymia Questionnaire (PAQ) across autistic and non-autistic samples. Using the PAQ, we investigated how alexithymia manifests in autistic individuals and its links with poor mental health outcomes (anxiety).

Methods:

Autistic individuals (who reported having a diagnosis from a health professional; n = 244) and non-autistic individuals (n = 383; age range: 16–62 years) completed the PAQ and a trait anxiety questionnaire online. We conducted confirmatory factor analysis, item response theory (IRT), and moderated nonlinear factor analyses to investigate the psychometric properties of the PAQ and alexithymia differences between autistic and non-autistic individuals. Regression analyses investigated the relationships between alexithymia and anxiety and whether these relationships differ for autistic or non-autistic populations.

Results:

As operationalized by the PAQ, alexithymia manifested similarly in autistic and non-autistic individuals, comprising a general alexithymia factor and five subfactors: positively and negatively valenced difficulties identifying feelings, positively and negatively valenced difficulties describing feelings, and externally oriented thinking. All factors exhibited good to excellent classical test theory and IRT-derived reliability. The PAQ did not meaningfully bias scores for autistic individuals, who reported greater alexithymia across all its components. Alexithymia predicted greater anxiety, with nuances regarding externally oriented thinking particularly for autistic individuals.

Conclusions:

For the first time, our study illustrates that all facets of alexithymia can be validly and comprehensively assessed in autistic populations. As measured via the PAQ, alexithymia manifests similarly across autistic and non-autistic individuals, and on average, autistic individuals have greater challenges across all aspects of alexithymia. The PAQ, therefore, represents a critical assessment advancement for the field, providing a foundation for future work on alexithymia and autism.

Community Brief

Why is this an important issue?

Many autistic individuals report struggling to focus on, identify, and describe their feelings, an experience known as alexithymia. People experiencing alexithymia may have challenges managing their emotions and can face mental health difficulties (e.g., anxiety). We do not know why autistic individuals are more likely to experience alexithymia. However, some researchers point to the different communication and emotional styles used by autistic and non-autistic individuals. To help autistic individuals experiencing alexithymia, it is crucial to assess it accurately. Until this study, there was no valid way of comprehensively assessing alexithymia in autistic individuals.

What was the purpose of this study?

This study wanted to know (1) whether alexithymia in autistic individuals involved difficulties attending to, identifying, and describing positive (e.g., happiness) and negative (e.g., sadness) feelings; (2) whether a commonly used alexithymia questionnaire, the Perth Alexithymia Questionnaire (PAQ), accurately measures alexithymia in autistic individuals; (3) whether autistic individuals experience greater alexithymia than non-autistic individuals; and (4) whether individuals with more alexithymia experience greater anxiety.

What did the researchers do?

We recruited 244 autistic and 383 non-autistic individuals online through a website called Prolific, who then completed the PAQ and an anxiety questionnaire. To be included as an autistic participant, individuals had to report having a formal autism diagnosis from a health professional (excluding individuals who self-identified as autistic but did not have a formal diagnosis). We then used advanced statistical analyses to answer what we wanted to know.

What were the results of the study?

The PAQ accurately and fairly assessed alexithymia in autistic individuals. Alexithymia includes multiple characteristics, including difficulties paying attention to feelings, identifying positive or negative feelings, and describing positive or negative feelings. The PAQ also does not bias scores for autistic individuals. Lastly, while autistic individuals, on average, reported experiencing more alexithymia than non-autistic individuals, this was not true for all autistic individuals.

Individuals with greater alexithymia experience greater anxiety. Interestingly, we found some evidence that autistic individuals with alexithymia may avoid focusing on their emotions to reduce their anxiety.

What do these findings add to what was already known?

There is now a valid measure of alexithymia for autistic individuals. Additionally, the findings help us better understand how alexithymia presents in autistic individuals and the impact of alexithymia on anxiety.

What are potential weaknesses in the study?

One limitation of our study is that we recruited individuals online. We were unable to verify whether autistic individuals had an autism diagnosis or not, and we excluded self-identifying autistic individuals. As such, we do not know how alexithymia presents or what it may impact in these autistic individuals.

How will these findings help autistic adults now or in the future?

We now have a way to assess alexithymia in autistic individuals. Practitioners can use the PAQ to identify which autistic clients may benefit from support around their alexithymia. Additionally, as the PAQ is freely available, autistic adults can access it to see if they experience high levels of alexithymia. In the future, more research will uncover the best ways to support autistic individuals experiencing alexithymia.