Abstract
Despite average intellectual capacity, autistic traits may complicate performance in many everyday situations, thus leading to stress. This study focuses on stress in everyday life in intellectually able adults with autism spectrum disorders. In total, 53 adults (25 with autism spectrum disorder and 28 typical adults from the general population) completed the Perceived Stress Scale. Autistic traits were assessed using the Autism Spectrum Quotient. Adults with autism spectrum disorder reported significantly higher subjective stress and poorer ability to cope with stress in everyday life, as compared to typical adults. Autistic traits were associated with both subjective stress/distress and coping in this cross-sectional series. The long-term consequences of chronic stress in everyday life, as well as treatment intervention focusing on stress and coping, should be addressed in future research as well as in the clinical management of intellectually able adults with autism spectrum disorder.
Keywords
Introduction
Autism spectrum disorders (ASDs) in adults are associated with psychiatric and psychosocial problems, and these difficulties are not limited to groups with intellectual difficulties (Hofvander et al., 2009). Despite average intellectual capacity, autistic traits may complicate performance in many everyday situations, including social interaction and communication in different work, leisure activity, and family situations. Autistic traits may also impair performance when there are unplanned changes in the individual’s usual routines (i.e. when flexibility is required), thus leading to stress. The association between autistic traits and stress in everyday life in adults with ASD is a clinically relevant but understudied area of research.
Internal or external stimuli that an individual perceives as threatening (i.e. stressors) disturb the dynamic equilibrium of the body (i.e. homeostasis) and elicit a stress reaction. Notably, what is perceived as stressful differs from individual to individual. Moreover, the individual’s subjective perception of his or her ability to cope with the specific stressor, or perception of control, is crucial for the perception of distress (Karasek and Theorell, 1990). Previous studies investigating stress in ASD have focused on biological stress markers, such as adrenocorticotropic hormone (ACTH) (Tani et al., 2005) and cortisol (Brosnan et al., 2009; Tani et al., 2005; Zinke et al., 2010). Different stress responses (as compared to controls) have been observed in some of the studies (Brosnan et al., 2009; Tani et al., 2005), but not all (Zinke et al., 2010). However, self-perceived stress was not reported in these studies.
The first aim of this study was to describe level of self-perceived stress in intellectually able adults with ASD. We hypothesized that adults with ASD would describe more subjective distress and poorer coping ability than typical adults. The second aim was to study the hypothesis that autistic traits are correlated with both perceived stress (distress) and perceived coping ability.
Methods
Study setting
The study comprises part of a study of oral health in adults with ASD. Inclusion criteria were subjects aged 18 years or older with an ASD diagnosis living in the Northern Stockholm area in 2008. Exclusion criteria for participants with ASD were diagnosed intellectual disability, diagnosed attention-deficit hyperactivity disorder (ADHD), a history of brain damage, current or past medical or neurological disorder, epilepsy, alcohol abuse or dependence, past or present substance abuse, and psychosis. In addition, exclusion criteria for the typical adults were a positive outcome in a screening for neurodevelopmental disorders (ASD or ADHD).
Participants
Adults with ASD were recruited from a tertiary unit for diagnosing neurodevelopmental disorders in adulthood, as well as from a community-based unit for adults with ASD in Stockholm. The diagnoses of ASD were established according to Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) in consensus between a psychiatrist and a psychologist, both with solid experience in neurodevelopmental disorders. The participants were first contacted by means of an invitation letter. The recruitment procedure is described in detail in Figure 1. The final study group comprised 25 adults with ASD (15 males, 10 females).
Flowchart of participants with ASD (F = females; M = males).
In total, 28 typical adults (12 males, 16 females) were recruited from six private dental clinics in Stockholm. The typical adults were matched with the ASD group with regard to age, gender, and residential area. In order to screen for behaviors related to neurodevelopmental disorders, the typical adults completed the Adult ADHD Self-Report Scale (ASRS) Screener (Kessler et al., 2005) and the Autism Spectrum Quotient (AQ) questionnaire (Baron-Cohen et al., 2001). The ASRS Screener comprises the first six questions of the ASRS. A dichotomous version of the six-question ASRS Screener has been shown to have adequate sensitivity and excellent specificity (Kessler et al., 2005). A score of 4–6 on the dichotomous ASRS Screener was considered to be a positive outcome (Kessler et al., 2005). For screening purposes, a positive outcome in the AQ questionnaire was defined as 32 answers indicating “definitely agree” or “slightly agree” out of 50 questions (Baron-Cohen et al., 2001). None of the typical adults had a positive outcome in this screening.
The two groups (ASD and typical adults) were comparable with regard to age, within-group gender distribution, and Swedish versus non-Swedish origin, as well as educational level. However, in the ASD group, the majority were not working or studying at the time of the study (Table 1).
Sample characteristics.
ASD: autism spectrum disorder; AQ: Autism Spectrum Quotient; SD: standard deviation.
Data missing for one individual in the control group.
Measurements
Demographic and background information
Demographic and background information was collected from the participants in conjunction with the dental appointment, using a self-administered questionnaire. All participants had the opportunity to ask for clarification of the items in this questionnaire, as well as the following self-rating scales.
Self-rating scales
The AQ (Baron-Cohen et al., 2001) is a self-rating scale that describes a variety of behaviors typically observed in individuals with ASD. The AQ is not only sensitive in diagnosed individuals, but it can also detect variance in non-clinical autistic traits (Baron-Cohen et al., 2001). The AQ consists of 50 items and the participants rated to what extent they agreed or disagreed with the statement. To optimize variance in the data for the correlation analyses, the answers were rated on a 4-point Likert scale, from “definitely agree” (1) to “definitely disagree” (4) (and not as a dichotomous scale used for screening of typical adults as described above). All item scores were summed up, resulting in a minimum total AQ score of 50 (no autistic traits) and a maximum score of 200 (full endorsement on all autistic traits).
The Perceived Stress Scale (PSS) (Cohen et al., 1983) was used to assess subjective stress. The PSS is a widely used self-rating questionnaire for measuring the degree to which situations in one’s life are appraised as stressful, that is, how unpredictable, uncontrollable, and overloaded respondents find their lives. The Swedish version of the PSS, based on the original 14-item scale (scored 0–4; total score 0–56), was chosen, and the total PSS score was calculated as a sum of all items (Hirvikoski et al., 2009). Factor analysis of the original 14-item PSS (Hewitt et al., 1992) has revealed a two-factor structure: Distress, a factor of items reflecting adaptational symptoms (e.g. “upset because of something that happened unexpectedly” and “ felt nervous and stressed”), and Coping, reflecting coping ability (e.g. “dealt successfully with irritating life hassles” and “ felt confident about your ability to handle your personal problems”). High scores on Distress subscale indicate high subjective stress, and high scores on Coping subscale reflect poor perceived coping ability. The PSS Distress and PSS Coping factors were used in analyses of the association between ASD-related behaviors (measured with the AQ) and perceived distress and coping.
Statistical analyses
Data were tested for normal distribution (Kolmogorov–Smirnov), homogeneity (Levene’s test), and univariate outliers (using >2.5 SDs from the group mean value as a definition of an outlier; no outliers were detected). For comparisons of the two groups, we used Student’s t-test for continuous variables and the chi-square test for categorical variables. The effect sizes for the t-tests were expressed as Cohen’s d. The association between the ASD-related behaviors, as measured with the AQ, versus the PSS Distress factor and the PSS Coping factor, was calculated using the Pearson correlation. We also calculated (post hoc) correlation between the AQ score and the total PSS score in separate analyses for the two groups (typical adults versus adults with ASD). The alpha level was set at 0.05 for all analyses.
Results
Level of self-perceived stress
In the total score of the PSS, the ASD group scored significantly higher than the typical adults (ASD, M = 29.38, SD = 11.07; typical, M = 19.69, SD = 6.38; t(37.41) = 3.85, p < 0.001, d = 1.07). Similarly, a significant large effect of the diagnostic status was observed in both the Distress subscale (ASD, M = 14.56, SD = 6.27; typical, M = 9.58, SD = 4.01; t(40.01) = 3.40, p = 0.002, d = 0.95) and the Coping subscale (ASD, M = 8.66, SD = 3.79; typical, M = 5.71, SD = 2.28; t(38.37) = 3.38, p = 0.002, d = 0.94).
Association between autistic traits and stress
The total AQ score was significantly correlated with PSS Distress (r = 0.64, r2 = 0.41, p < 0.001, n = 52 including 28 typical adults and 24 individuals with ASD; AQ data missing for one individual with ASD) and PSS Coping (r = 0.63, r2 = 0.40, p < 0.001), respectively (Figure 2). In post hoc separate analysis for the two groups, the correlation of AQ with total PSS score was 0.45 (p = 0.02) for typical adults and 0.62 (p = 0.001) for adults with ASD.
Autistic traits, measured with the AQ, significantly correlated with both the PSS Distress subscale (right panel) and the PSS Coping subscale (left panel) (both p values < 0.001).
Discussion
In this study, intellectually able adults with ASD reported a high level of subjective stress and a perception of low coping ability regarding stressors in everyday life. Autistic traits were associated with both the perception of distress and coping ability. The correlation between the measures of perceived stress and autistic traits was also significant when calculated separately for typical adults versus adults with ASD and thus not driven solely by one of the groups.
The high level of self-perceived stress in the ASD group corresponded to a large effect and to the levels previously observed in adults with ADHD, (Hirvikoski et al., 2009). These results may reflect the challenges adults with neurodevelopmental disorder encounter in everyday life. It is known that individuals with ASD often show problems with executive functions (Kenworthy et al., 2008) which can impede their choosing appropriate coping strategies. Other aspects related to ASD (in intellectually able individuals) that may both predict subjective stress and lead to stressful situations are common co-existing psychiatric problems (Hofvander et al., 2009), sensory processing difficulties (Horder et al., 2013), and impaired adaptive behaviors (Kenworthy et al., 2010). Taken together, these difficulties may complicate seemingly simple everyday situations (e.g. home duties, public transport, informal social commerce, etc.). Autistic traits may also restrict the individual’s ability and/or willingness to seek help and social support.
The core symptoms of ASD, could not only be associated with distress and coping, as in this study, but also frequently bring about stressful situations in everyday life among intellectually able adults with ASD. Thus, intellectually able adults with ASD may be exposed to many stressful situations in everyday life while facing these situations with poor coping strategies and perceptions of high distress.
Limitations
We included adults with ASD and no diagnosis of intellectual disability or ADHD, but did not measure intelligence. However, the assessment of intellectual performance was a routine in Sweden by the time of the study, which is why we consider the diagnostic status regarding intellectual performance valid. The (at least) average intelligence was also demonstrated by the above-mentioned fact that the level of education did not differ from that of the typical adults from general population. Thus, the reported difficulties in coping would not appear to be related to intellectual capacity although slight between-group differences cannot be excluded. Moreover, there are several methodological limitations that can affect the interpretation of the results. First, our study group consisted of intellectually able adults with ASD diagnosed as adults, and it may not be possible to generalize the results to other groups with ASD. For example, an early diagnosis and support during transition from adolescence to adulthood may enhance coping ability and alleviate perceived stress. Finally, the relatively small sample sizes limited analyses of the impact of the demographic variables (such as gender) on self-perceived stress and coping ability.
Clinical significance and future work
Bearing in mind the above limitations, the study still indicated that people with ASD may experience high levels of stress in everyday life. Chronic stress may reduce individual’s ability to participate in different settings in community (e.g. regarding work, leisure, and social activities) and heighten the risk of the somatic burden of the accumulated lifetime stress (McEwen, 2004). Thus, subjective stress and coping ability should be assessed in conjunction with a broad clinical assessment of ASD. It also seems to be crucial to develop treatments focusing on coping skills and management of stress in everyday life (Pahnke et al., 2013). Moreover, an important focus for future research is to investigate how stress interacts with cognition (both general intellectual ability and executive functioning), perception, adaptive behaviors, and psychiatric difficulties in intellectually able adults with ASD.
Footnotes
Acknowledgements
We would like to thank Associate Professor Susanne Bejerot for giving us the opportunity to implement the study at the Neuropsychiatric Unit, Northern Stockholm Psychiatry Clinic, as well as Professor Sven Bölte at the Center for Neurodevelopmental Disorders at Karolinska Institutet (KIND) and Professor Göran Dahllöf at Department of Dental Medicine at Karolinska Institutet for advice and support.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.