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Alexithymia is considered a “sub-clinical phenomenon” (Silani et al. 2008) and doesn’t identify a personality disorder per se but is a personality trait that is dimensional in nature (Taylor et al. 1991). Alexithymia is not a symptom of autism, but rather an independent construct that frequently co-occurs with autism. Although alexithymia has similar symptoms, it is distinct from autism – it is neither a necessary nor sufficient feature for an autism diagnosis, and there are autistic people without alexithymia and alexithymic people without autism – but alexithymia is much more common among autistic people than among the neurotypical population (Brewer et al. 2015).
Despite the extensive research dedicated to exploring the connection between alexithymia and ASD, a definitive answer regarding their precise relationship remains elusive. It is still unclear whether this relationship should be viewed in causal terms (and if so, in which direction) or coincidental. It is also uncertain whether one condition might result from the dysfunctions caused by the other, suggesting potential comorbidity or epiphenomenal relationship. Alternatively, it is possible that the co-occurrence of alexithymia and ASD is simply a coincidental occurrence that has yet to be fully understood.
Etiological perspectives
While there is an apparent overlap between alexithymia and ASD, the two disorders may have different causes. E.g., the genetic and neurochemical underpinnings of the disorders may be different (Hill & Berthoz 2006). Alexithymia in people with ASD may involve a disruption in how physiological arousal modulates the subjective experience of feelings (Gaigg et al. 2018).
Cognitive issues
Research suggests that difficulties in emotion recognition and theory of mind are both associated with autistic traits, and this is not accounted for by individual differences in levels of alexithymia (Moraitopoulou et al. 2024). Autism is associated with atypical theory of mind but not empathy, while alexithymia is associated with atypical empathy but not theory of mind (Brewer et al. 2015).
A concrete, utilitarian thinking style, not dissimilar to “operative thinking,” is common in alexithymia (Suslow, Junghanns 2002) and ASD, though its impact on moral judgment differs between alexithymia and ASD (Lemche et al. 2004).
Sensory processing
Some studies have outlined how alexithymia in people with ASD may be interpreted as a consequence of the extreme sensory processing patterns of ASD (Serafini et al. 2017), and, more specifically, of the atypical sensory function and associated intolerance of uncertainty, possibly due to a deficit in limbic-, insula-, and medial prefrontal cortex-based network integration (South & Rogers 2017).
The alexithymia hypothesis
The alexithymia hypothesis suggests that certain aspects of socio-cognitive functioning typically attributed to autism, namely difficulties in emotion recognition, might be better explained by often co-occurring alexithymia (Bird, Cook 2013).
Social functioning and empathy
Both ASD and alexithymia have difficulties with social interactions. However, the presence of alexithymia may have a greater impact on social and emotional functioning of ASD individuals than previously thought. Higher alexithymia traits predict lower levels of social competence.
There is a significant range of social difficulties observed in ASD individuals. The variability in these impairments has been linked to the presence or absence of alexithymia. These findings indicate that alexithymic traits, rather than autistic traits, may be the primary factor influencing prosocial behaviour across the autism spectrum (Lischke et al. 2022).
Research shows that autistic children with more alexithymia problems had poorer social skills (Scheerer, Boucher, Iarocci 2021). Severity of alexithymia symptoms predict fewer social interactions in autistic adults regardless of ASD status, suggesting that alexithymia, not ASD severity, may drive social isolation (Gerber et al. 2019).
Empathy
Empathy difficulties, traditionally viewed as core features of autism, may actually be due to co-occurring alexithymia. Alexithymia predicts empathy deficits better than autistic traits, supporting the alexithymia hypothesis (Speyer et al. 2022).
The data suggest that interoceptive dysfunctions that underpin the core symptomatic emotion recognition and empathy deficits in ASD may be contributed to by high levels of alexithymia rather than autistic symptoms per se (Li et al. 2019). These findings are suggestive of an alexithymic subgroup in ASD, with distinct interoceptive processing abilities, and have implications for diagnosis and interventions (Mul et al. 2018).
Interoception
Impaired interoception, i.e., problems with perceiving internal bodily signals, is a candidate mechanism underlying alexithymia (Herbert et al. 2011). However, interoceptive difficulties have also been implicated in ASD and this impairment may contribute to social cognitive dysfunctions. Research suggests alexithymia serves as an important node, bridging interoceptive deficits, self-awareness, and empathic impairments of ASD (Yang et al. 2022).
There is no evidence that ASD (in the absence of comorbid alexithymia) is associated with a failure of interoception, so some researchers suggest that alexithymia, rather than autism, is most accurately characterised as a general failure of interoception (Shah et al. 2016).
Co-occurring alexithymia, driven by poor interoception, may signify a particular subgroup of individuals with ASD who experience emotional as well as core autistic difficulties. This implies that managing the emotional difficulties in ASD may be possible without needing to “treat” the core features of ASD (Livingston & Livingston 2016).
Emotional Dysregulation and Expression Difficulties
It is widely accepted that autism is associated with difficulties processing, recognising and expressing emotions (verbally and nonverbally) (Cook et al. 2003; Ola & Gullon-Scott 2020; Gehdu et al. 2023; and others). Bird & Cook (2013) argue that emotional impairments are due to alexithymia rather than a feature of autism per se, i.e., alexithymia, not ASD, is a leading cause of the emotional deficits inherent to ASD symptomatology. Alexithymia may disrupt one of the steps in the hierarchy of internal and external emotional responses in people with ASD, which will affect their ability to respond appropriately to emotions. (However, there is a considerable
heterogeneity in emotional competence within the autistic population.)
Poquérusse et al. (2018) break down the phenomenon of emotional processing to determine where and how deficits arise, and how these are connected to the dynamic interplay between alexithymic and autistic traits. Their findings provide evidence that alexithymia can both trigger and result from autistic behaviours, i.e., alexithymia is both a cause and consequence of autistic behaviours (Poquérusse et al. 2018).
Mental health implications
Alexithymia is linked to worse mental health outcomes in autistic individuals, particularly regarding depression and social phobia. Research shows that alexithymia increases depression symptoms, while autistic traits increase social phobia symptoms (Albantakis et al. 2020). Additionally, the risk of suicidality among adults with ASD increases if they also have high levels of alexithymia (Costa et al. 2020).
There are more indirect links between alexithymia and ASD as well. Alexithymia in itself may cause anxiety and related sleep issues (Tani et al. 2004) and the inability to healthily express and externalise emotions can lead to various psychosomatic manifestations, including immune, gastrointestinal, and circadian disruptions, commonly seen in ASD (Poquérusse et al. 2018).
The relationship between alexithymia and ASD is complex and multifaceted. Further research is essential to understand the intricate interplay between these conditions. This understanding is vital for developing effective interventions and support strategies for individuals with both alexithymia and ASD.
Knowledge of alexithymia and interoception could be particularly useful for autistic individuals, their families and carers. For example, supporting people with ASD to be more aware of their internal bodily signals may be of therapeutic value (Livingston & Livingston 2016). Training interoceptive ability may also enhance emotional clarity and reduce alexithymia in autistic individuals (Bonete, Molinero, Ruisanchez 2023).
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