Discussion
The present study aimed to extend previous research regarding the
relationships between autism, anxiety and the mediating influence of IU
and SOR. Previous research has mainly focused on children with ASC, with
limited research studying autistic traits in anxious individuals,
particularly adults. Furthermore, there is a shortage of research
focusing on autism in women, resulting in arguments that there is a
poorly understood female phenotype which may be characterised by
elevated anxiety in women (Ludlow et al., 2015), and thus the argument
that women diagnosed with anxiety disorders may include some of the
undiagnosed female ASC population (Kim et al., 2011). In line with the
first hypothesis results indicated women with anxiety disorder diagnoses
had significantly higher autistic traits on average than general
population samples, with 21.1% meeting the clinical cut-off (over 20
times higher than general population). This finding may be explained by
the camouflaging hypothesis, in that women with autism have higher
anxiety due to the stress of masking their autistic traits (Lai et al.,
2017). Indeed, there were significant correlations between all measures
of anxiety and autistic traits, with each measure also correlating with
the two mediating factors of IU and SOR, in line with previous findings
(Bitsika et al., 2016).
While previous research has established ASC severity as a reliable
predictor of anxiety in autistic individuals (e.g. Lever & Guerts,
2016; Murry et al., 2019), little research has investigated whether
anxiety can predict autistic traits. The present study found all four
anxiety subtypes were individually significant predictors of autistic
traits, supporting the findings of van Steensel et al., (2013) in
children. Additionally, all four anxiety subtypes were predictive of
both IU and SOR, with these two factors also being significant
predictors of autistic traits.
Finally, IU has been identified as a key construct in a range of anxiety
disorders (Norr et al., 2013) as well as demonstrating links with ASC
(Neil et al., 2016), thus South and Rodgers (2017) propose that IU is
one mediator between ASC and anxiety, however previous research has
focused on autistic samples rather than those with anxiety disorders. As
far as we are aware, the present study has been the first to demonstrate
that IU was a significant partial mediator between all four anxiety
subtypes and autistic traits. For all anxiety subtypes the effect of
anxiety symptoms was not completely reduced when accounting for IU,
suggesting partial mediation in the model and that other factors may be
of influence. Indeed, SOR was also found to be a significant partial
mediator between all anxiety subtypes and autistic traits. The present
findings were in line with South and Rodger’s (2017) model and with
research linking SOR to a range of anxiety subtypes (Bitsika et al.,
2016).
As noted, IU and SOR only partially explained the relationship between
anxiety and autistic traits, indicating the presence of other mediating
factors. Indeed, South and Rodgers (2017) have identified alexithymia as
a further possible mediating factor that has been shown to mediate the
relationship between autistic features and anxiety (Morie et al., 2019)
though research has yet to investigate a possible mediating relationship
in the opposite direction. Additionally, alexithymia has also been
associated with SOR, bringing up another area of possible further
research regarding investigating the relationships between the mediating
factors themselves. Indeed, IU mediated the relationship between sensory
features and anxiety (Uljarević et al., 2016), and in autistic children
but not typically developing controls, SOR was found to mediate the
relationship between both separation anxiety and Specific Phobia
symptoms and the autistic trait of insistence on sameness (Black et al.,
2017).
Further variables that could also be investigated for potential
mediating effects include RRBs, which have been associated with both ASC
and OCD (Stewart et al., 2016) and have been linked to increased anxiety
in autistic samples (Rodgers et al., 2012). Indeed, Wigham et al. (2015)
found that the relationship between sensory atypicalities and RRBs was
mediated by IU, though research has yet to investigate the role of RRBs
in elevated autistic traits in anxious samples. Even within the
mediating variables investigated, there are further areas that could be
researched. For instance, both sensory over- and under-responsivity has
been associated with ASC (Ben-Sasson et al., 2007), as well as a range
of atypical processing across different domains of sensory function
including auditory and visual (Tavassoli et al., 2014), each of which
may have differential relationships with ASC and anxiety. For instance,
Bitsika, Arnold & Sharpley (2019) found that auditory-specific sensory
behaviours shared the strongest correlation with parent-rated anxiety in
autistic children and also identified the further variable of sensory
avoiding, finding that ASC symptoms influenced elevated levels of
parent-rated GAD indirectly through greater levels of sensory avoiding.
Understanding the relationship between autism and anxiety has
significant clinical implications, not only for the diagnosis of both
disorders but for the treatment of the two as comorbidities (Sung et
al., 2011). Anxiety in ASC is associated with increased levels of
repetitive behaviours (Lidstone et al., 2013), externalising problems
including aggression and self-injury (Mattila et al., 2010) and
loneliness (White & Roberson-Nay, 2009). Using the ASC-ASD anxiety
measure in autistic children, those scoring above the cut-off had poorer
scores on a range of quality of life (QoL) domains including social,
emotional, physical and school functioning, with regression analyses
demonstrating that the items relating to IU in particular predicted QoL
domains as well as poorer QoL overall (Adams, Clark & Keen, 2019),
emphasising the need for ASC adapted treatment (Rodgers & Olfield,
2018). Furthermore, as multiple anxiety disorders often occur
concurrently in ASC, symptoms are likely to have both interaction and
additive impacts on treatment efficacy. Adaptations to CBT for the
treatment of those with ASC include being taught social skills to
recognise emotions and identify triggers for anxiety (Sung et al.,
2011), parent management techniques to address broader deficits that may
be contributing to anxiety (Moree & Davis, 2010) and using virtual
reality to aid exposure treatment for phobias (Maskey et al. 2019), the
latter being useful for circumventing the common difficulties with
imagination in ASC (APA, 2013) which may impair engagement in imaginal
desensitisation. Further factors that have been identified as important
for the treatment of autistic individuals include regular sessions in a
structured setting, consistent therapists and social exposure as well as
the use of autism-friendly strategies such as visual strategies or
role-plays (Sung et al., 2011).
The results of the present study suggests that targeting IU and SOR may
be effective for treating anxiety, and indeed Keefer et al., (2017)
found that pre-intervention IU predicted higher anxiety in both pre- and
post-intervention measures, therefore indicating that directly targeting
IU may improve outcomes. Such treatments are in development, with
Rodgers et al., (2016) devising the Coping with Uncertainty in Everyday
Situations Program focused on IU, designed to specifically address a
target uncertain situation identified by the patient, and has shown
promise in both child (Rodgers et al., 2016) and adult samples (Rodgers,
Herrema, Honey & Freeston, 2018).
Regarding SOR as a target in the treatment of anxiety, treatments such
as Sensory Integration Therapy have focused on helping those with ASC to
regulate sensory experiences in order to alleviate ASC symptoms and
anxiety, but evidence is mixed and based primarily on case-study designs
which may not be generalizable (Lang et al., 2012), therefore more
research is required to investigate SOR as a potential target in the
treatment of anxiety. Finally, understanding autism in women is of
clinical significance as the majority of women report negative
experiences during the diagnostic process (Milner, Mcintosh, Colvert &
Happé, 2019) and the lack of understanding is suspected to lead to
delayed diagnosis (Bargiela et al., 2016). Reducing this delay is
significant when those who are not diagnosed until adulthood are less
likely to receive adequate educational support compared to those
diagnosed earlier (Baldwin & Costley, 2016).
Despite being one of the few studies to investigate autistic traits in
anxious samples, there are a number of limitations to this study,
including that the relationship between autistic traits and anxiety
symptoms may be a consequence of diagnostic overshadowing between ASC
and anxiety disorders due to overlapping diagnostic criteria. For
example, SAD and ASC have a number of shared symptoms, including social
avoidance and a failure to speak in social situations (APA, 2013), with
57.1% of an autistic sample reporting clinically significant SAD
symptoms (Kuusikko et al., 2008). White et al. (2012) argue SAD and ASC
are separable but highly correlated disorders, with unique factors
relating to each disorder, and evidence supports different developmental
trajectories of shared deficits in emotion recognition, which are traced
to early delays in mimicry and imitation in ASC yet have been related to
temperamental and environmental factors such as developing biases
towards threatening interpretations of stimuli in SAD (Tyson & Cruess,
2001). Cath, Ran, Smit, Van Balkom and Comijs (2008) found that the AQ
subscales of communication problems and lack of imagination
discriminated between those with a dual diagnosis of ASC and SAD and
those only diagnosed with SAD. Similarly, Hartley and Sikora (2009)
found that scores on communication and social interaction difficulties
scales could differentiate between those with ASC and those with anxiety
disorders. Finally, while White, Schry & Kreiser (2014) acknowledge
that distinguishing the symptoms of SAD from those of ASC may be
difficult for clinicians, they conclude that the two are separable
clinical constructs, and that social anxiety can be statistically
separated from ASC symptom severity (White et al., 2012).
As well as possible conceptual limitations, there are a number of
methodological limitations, including issues regarding how mediation
might not be best tested cross-sectionally, (Cole and Maxwell, 2003).
Future research should aim to explore these findings using a
longitudinal design.
A further limitation relates to the anxiety measures used, the majority
of which are designed for use in typically developing individuals and
thus may not accurately differentiate autism and anxiety symptoms. This
is particularly true when considering that emotion recognition deficits
associated with autism, such as alexithymia, may result in difficulties
in accurately self-reporting anxiety (White et al., 2014).
In conclusion, the present study has demonstrated that autistic traits
can be predicted by anxiety, and that this relationship is partially
mediated by SOR and IU. However, there is a lack of research on autism
in anxious populations and more research is required to corroborate
these findings, as well as investigating other factors which may also
play a role in the relationship between autism and anxiety, such as
alexithymia. Further research would also benefit from tackling some of
the limitations of this study, for example by using a longitudinal
design, and exploring these findings in other populations.