Trait Anxiety In Individuals On The Autism Spectrum: A Systematic Review

Jolliffe, R., Adams, D., & Simpson, K. (2023). Trait anxiety in individuals on the autism spectrum: a systematic review. Review Journal of Autism and Developmental Disorders, 10(3), 523-545. https://doi.org/10.1007/s40489-022-00308-8

Anxiety is frequently observed in autistic individuals. Signs of anxiety in autism can include increased repetitive behaviors, avoidance of social situations, sleep disturbances, and heightened sensory sensitivities.

Anxiety disorders such as social anxiety, generalized anxiety disorder, and specific phobias are also common co-occurring conditions in autism.

The high prevalence of anxiety in autistic individuals may be due to a combination of factors including difficulties with social interaction, sensory processing differences, and cognitive inflexibility.

Understanding and addressing anxiety is crucial for improving quality of life for autistic individuals.

Key Points

• The primary methods of measuring trait anxiety in individuals with autism spectrum disorder (ASD) include self-report questionnaires, with the State-Trait Anxiety Inventory for Children-Trait subscale (STAIC-T) and State-Trait Anxiety Inventory-Trait subscale (STAI-T) being the most commonly used measures.
• Factors like gender, age, intellectual ability, and cultural background significantly affect the measurement and expression of trait anxiety in individuals with ASD. However, current research lacks diversity in these areas.
• Most studies found significantly higher trait anxiety scores in individuals with ASD compared to neurotypical controls. Trait anxiety was associated with increased alexithymia and irritability and decreased emotion recognition and social responsiveness in some studies.
• The research, while enlightening, has certain limitations such as lack of diverse participant samples, inadequate reporting of study details, and use of anxiety measures not yet validated for individuals with ASD.
• Trait anxiety is an important construct to study in ASD given the high prevalence of anxiety in this population and its potential impacts on functioning and quality of life. Understanding trait anxiety could inform interventions and supports.

Rationale

This systematic review aimed to synthesize and evaluate existing research on trait anxiety in individuals with autism spectrum disorder (ASD). The rationale for conducting this review stems from several key factors:

1. High prevalence of anxiety in ASD: Anxiety is one of the most common co-occurring conditions in ASD, with a lifetime prevalence of clinically elevated anxiety estimated at 42% (Hollocks et al., 2019). However, much of the existing research has focused on specific anxiety disorders rather than general trait anxiety.
2. Importance of trait anxiety: Trait anxiety refers to a general personality trait of anxiety proneness, as opposed to state anxiety which is a transient emotional response (Spielberger, 1966). High trait anxiety has been associated with increased risk for developing anxiety disorders and other mental health issues in the general population (McEwen & Gianaros, 2011).
3. Limited research on trait anxiety in ASD: While anxiety disorders in ASD have been widely studied, there has been relatively little research specifically examining trait anxiety in this population. Understanding trait anxiety in ASD could provide insights into anxiety vulnerability and inform interventions.
4. Measurement challenges: Accurately assessing anxiety in individuals with ASD can be challenging due to diagnostic overshadowing, communication difficulties, and potential ASD-specific anxiety presentations (Kerns & Kendall, 2012; Kerns et al., 2014). It is important to evaluate how trait anxiety is being measured in this population.
5. Need for synthesis: With the growing body of research on anxiety in ASD, a systematic review was needed to consolidate findings specifically related to trait anxiety, identify trends, evaluate methodological quality, and highlight gaps for future research.

By addressing these rationales, this review aimed to provide a comprehensive overview of the current state of knowledge regarding trait anxiety in ASD and inform future research directions in this important area.

Method

This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review protocol was registered with PROSPERO (registration number: CRD42020207483).

Search strategy and terms:

Eight electronic databases were searched in September 2020 with an update in March 2021: CINAHL, Embase, ERIC, MEDLINE, ProQuest Central, PsycINFO, Scopus, and Web of Science.

The search string used was: (autis* OR asd OR asc OR asperger* OR “pervasive development* disorder*” OR pdd OR hfa) AND (trait NEAR/10 anxi*). Database-specific syntax was used as needed.

Inclusion criteria:

1. Original peer-reviewed studies published in English between 1994-2020
2. Used a reliable diagnostic/screening measure to confirm ASD diagnosis
3. Measured trait anxiety as specified by study authors
4. Reported trait anxiety data for ASD participants separately

Exclusion criteria:

1. No reliable ASD diagnostic/screening measure used
2. Did not specify measuring trait anxiety
3. Trait anxiety not measured in individuals with ASD
4. ASD group trait anxiety results not presented separately
5. Reviews, meta-analyses, case studies, dissertations, etc.

The initial search yielded 1099 records. After removing duplicates, 451 titles/abstracts were screened, with 296 full-text articles assessed for eligibility.

A total of 23 studies met all inclusion criteria and were included in the review.

Statistical measures

Due to the heterogeneity of included studies, a narrative synthesis approach was used rather than meta-analysis. Descriptive statistics were used to characterize study and participant features.

Cohen’s kappa was calculated to assess inter-rater reliability for study selection. Percentages were used to evaluate reporting quality based on STROBE and CONSORT checklists.

Results

Prevalence and Severity of Trait Anxiety in ASD:

• 18 studies (78.3%) compared trait anxiety between ASD and neurotypical (NT) groups
• Most studies found significantly higher trait anxiety scores in ASD:
  • 5 out of 7 child studies (71.4%) reported higher trait anxiety in ASD vs. NT
  • 10 out of 11 adult studies (90.9%) reported higher trait anxiety in ASD vs. NT
• One study (South et al., 2017) found that NT adults with high anxiety scored higher on trait anxiety than both ASD and low-anxiety NT groups

Factors Associated with Trait Anxiety in ASD:

• Alexithymia: Milosavljevic et al. (2016) found adolescents with ASD and high alexithymia had higher trait anxiety than those with low alexithymia
• Autism Characteristics: Three adult studies reported positive correlations between trait anxiety scores and measures of autism traits (AQ and SRS-2)
• Emotion Recognition: Two studies indicated a relationship between higher trait anxiety and poorer emotion recognition in ASD
• Depression: Zukerman et al. (2019b) found a positive correlation between trait anxiety and depression scores in adults with ASD
• Age and IQ: No significant correlations were reported between trait anxiety and age or IQ in ASD groups

Physiological Correlates of Trait Anxiety in ASD:

• Mixed findings regarding correlations between trait anxiety and physiological measures:
  • One study found high parent-reported trait anxiety predicted dampened heart rate reactivity to stress in adolescents with ASD
  • Most studies (4 out of 5) found no significant correlation between trait anxiety and salivary cortisol response to stress in children with ASD
  • No significant correlations were found between trait anxiety and measures of brain activity (fMRI, EEG) in adults with ASD

Trait Anxiety Across Different ASD Subgroups:

• Limoges et al. (2005) reported no significant differences in trait anxiety scores between high-functioning autism and Asperger’s syndrome subgroups
• Althaus et al. (2015) found higher heterogeneity in trait anxiety scores within the ASD group compared to the NT group

Trait Anxiety and Functional Outcomes in ASD:

• Corbett et al. (2017) found that lower trait anxiety scores correlated with increased time spent in peer engagement during a play task
• Trait anxiety scores did not significantly correlate with measures of sleep quality, memory task performance, or academic results in ASD

Interventions Targeting Trait Anxiety in ASD:

• Two studies on a theatre-based intervention reported significant reductions in trait anxiety scores in children with ASD post-intervention
• One study on a social skills training program found no significant change in trait anxiety scores in adolescents with ASD

Measurement of Trait Anxiety in ASD:

• All studies relied on self-report measures, with STAIC-T (for children) and STAI-T (for adults) being most common
• Only two studies included parent-report measures in addition to self-report
• Limited reporting of psychometric properties for ASD samples:
  • Only two studies reported reliability data for ASD participants
  • No studies reported on validity of measures for ASD populations
• 21 out of 23 studies used measures not yet validated for use in ASD

Insight

This systematic review provides several key insights into the current state of research on trait anxiety in autism spectrum disorder (ASD):

1. Higher trait anxiety in ASD: The consistent finding of elevated trait anxiety scores in individuals with ASD compared to neurotypical controls aligns with the broader literature on anxiety in ASD. This suggests that individuals with ASD may have a general predisposition to anxiety beyond specific anxiety disorders.
2. Measurement challenges: The reliance on self-report measures not validated for ASD populations raises questions about the accuracy of trait anxiety assessment in this group. The lack of reported psychometric properties for ASD samples is concerning and limits the confidence in reported findings.
3. Limited diversity: The overrepresentation of male participants from Western countries and exclusion of older adults and individuals with intellectual disability limits the generalizability of findings. This highlights a significant gap in understanding trait anxiety across the full spectrum of individuals with ASD.
4. Complex relationships: The mixed findings regarding correlations between trait anxiety and other variables (e.g., physiological measures, emotion recognition) suggest complex relationships that warrant further investigation. This complexity may reflect the heterogeneity of ASD presentations.
5. Potential for intervention: While limited, the intervention studies included suggest that trait anxiety in ASD may be modifiable through targeted interventions. This is an important area for future research given the impact anxiety can have on quality of life for individuals with ASD.

These findings extend previous research by providing a focused examination of trait anxiety in ASD, highlighting both the prevalence of elevated trait anxiety and the methodological challenges in this area.

Future research should prioritize:

1. Developing and validating trait anxiety measures specifically for ASD populations
2. Including more diverse samples across age, gender, cognitive ability, and cultural backgrounds
3. Investigating the relationship between trait anxiety and ASD-specific characteristics
4. Exploring targeted interventions for reducing trait anxiety in ASD

Strengths

The study had several methodological strengths including:

1. Comprehensive search strategy: Eight databases were searched using a well-defined search string, increasing the likelihood of capturing relevant studies.
2. Adherence to guidelines: The review followed PRISMA guidelines and was pre-registered, enhancing transparency and reproducibility.
3. Rigorous selection process: Two independent raters screened studies with strong inter-rater reliability, reducing potential bias in study selection.
4. Quality assessment: The use of standardized checklists (STROBE and CONSORT) to evaluate reporting quality provides valuable context for interpreting study findings.
5. Detailed data extraction: Comprehensive data extraction covered multiple aspects of each study, allowing for thorough analysis of trends and gaps in the literature.
6. Focus on psychometric properties: By examining the reporting of psychometric properties, the review highlights an important methodological issue in this research area.

Limitations

The review has several limitations that should be considered:

1. Geographical restrictions: Most included studies were conducted in Western countries, limiting generalizability to other cultural contexts.
2. Demographic limitations: The overrepresentation of male participants and exclusion of older adults and individuals with intellectual disability restricts the applicability of findings across the autism spectrum.
3. Reliance on self-report measures: The exclusive use of self-report questionnaires may not capture the full complexity of trait anxiety in ASD.
4. Lack of longitudinal data: Most studies were cross-sectional, limiting understanding of how trait anxiety may change over time in ASD.
5. Limited intervention research: Only a few studies examined interventions for trait anxiety, providing limited evidence on effective treatments.
6. Potential publication bias: The review only included published, peer-reviewed studies in English, potentially missing relevant unpublished or non-English research.
7. Inability to conduct meta-analysis: Due to the heterogeneity of included studies, a quantitative meta-analysis was not possible, limiting the ability to draw more definitive conclusions about effect sizes.

These limitations highlight the need for more diverse and methodologically rigorous research on trait anxiety in ASD.

Implications

The findings of this systematic review have several important implications:

1. Clinical practice: The consistently higher trait anxiety found in autistic individuals suggests that clinicians should routinely screen for anxiety symptoms, even in the absence of a specific anxiety disorder diagnosis. This may help identify individuals who could benefit from anxiety management strategies or interventions.
2. Assessment methods: The lack of validated measures for assessing trait anxiety in ASD populations highlights the urgent need for developing and validating ASD-specific anxiety measures. Clinicians and researchers should be cautious when interpreting results from measures not validated for ASD.
3. Intervention development: The mixed findings from intervention studies suggest that more research is needed to develop effective treatments for reducing trait anxiety in ASD. Interventions may need to be tailored to address ASD-specific anxiety presentations.
4. Lifespan perspective: The absence of research on older autistic adults emphasizes the need for a lifespan approach to understanding trait anxiety in this population. This has implications for long-term care and support services.
5. Diversity considerations: The limited diversity in study samples highlights the importance of considering how factors such as gender, cognitive ability, and cultural background may influence the expression and experience of trait anxiety in ASD.
6. Research priorities: The review identifies several key areas for future research, including the need for more diverse samples, longitudinal studies, and investigations into the relationship between trait anxiety and ASD-specific characteristics.
7. Educational implications: Understanding trait anxiety in ASD could inform educational strategies and supports for students on the autism spectrum, potentially improving academic outcomes and overall well-being.

These implications underscore the significance of trait anxiety as an important construct in ASD research and clinical practice, with potential impacts on diagnosis, treatment, and support across various life domains.

References

Primary reference

Jolliffe, R., Adams, D., & Simpson, K. (2023). Trait anxiety in individuals on the autism spectrum: a systematic review. Review Journal of Autism and Developmental Disorders, 10(3), 523-545. https://doi.org/10.1007/s40489-022-00308-8

Other references

Hollocks, M. J., Lerh, J. W., Magiati, I., Meiser-Stedman, R., & Brugha, T. S. (2019). Anxiety and depression in adults with autism spectrum disorder: a systematic review and meta-analysis. Psychological medicine, 49(4), 559-572.

Kerns, C. M., & Kendall, P. C. (2012). The presentation and classification of anxiety in autism spectrum disorder. Clinical Psychology: Science and Practice, 19(4), 323.

Kerns, C. M., Kendall, P. C., Berry, L., Souders, M. C., Franklin, M. E., Schultz, R. T., Miller, J., & Herrington, J. (2014). Traditional and atypical presentations of anxiety in youth with autism spectrum disorder. Journal of autism and developmental disorders, 44, 2851-2861. https://doi.org/10.1007/s10803-014-2141-7

McEwen, B. S., & Gianaros, P. J. (2011). Stress-and allostasis-induced brain plasticity. Annual review of medicine, 62(1), 431-445. https://doi.org/10.1146/annurev-med-052209-100430

Spielberger, C. (1966). Theory and research on anxiety. In C. Spielberger (Ed.), Anxiety and behavior. Academic Press.

Keep Learning

1. How might cultural differences influence the expression and measurement of trait anxiety in individuals with ASD?
2. What are the potential benefits and drawbacks of developing ASD-specific trait anxiety measures versus adapting existing measures?
3. How might trait anxiety interact with core ASD characteristics to influence overall functioning and quality of life?
4. What ethical considerations should be taken into account when conducting anxiety research with individuals who have ASD and intellectual disability?
5. How could understanding trait anxiety in ASD inform the development of more personalized interventions or supports?
6. What role might sensory sensitivities play in the experience of trait anxiety for individuals with ASD?
7. How might trait anxiety in ASD change across the lifespan, and what factors could influence these changes?
8. In what ways could high trait anxiety be adaptive or beneficial for some individuals with ASD?