Understanding relationships between restricted repetitive behaviours and mental health in autistic people without intellectual disability

  • Nahory Hernandez Mancilla

Student thesis: Doctoral ThesisDoctor of Health (DHealth)


Background: Autistic people are at increased risk of developing depressive (Simonoff et al., 2008; Ghaziuddin, Ghaziuddin, & Greden, 2002) and anxiety conditions (Jenkinson et al., 2020; Rodgers, Riby, et al., 2012; van Steensel et al., 2011), and restricted repetitive behaviours (RRBs) in autism have been linked to these conditions in the past. However, there is scarce literature focusing on this topic, especially in autistic adults without intellectual disability. Furthermore, there is limited literature including special interests as a separate subtype of RRBs.

Objectives: The present study aimed to explore differences in the three RRB subtypes of special interests, repetitive sensory-motor behaviours (RSMBs) and insistence on sameness (IS), and the three mental health subtypes of depression, anxiety and stress in autistic compared to non-autistic adults, as well as the relationship between RRBs and mental health between the groups. It was expected the autistic group would have higher RRBs and mental health scores than the non-autistic group, and that there would be a stronger relationship between RRBs and mental health measures for the autistic versus the non-autistic group.

Methods: The study was co-designed with autistic and non-autistic individuals from different countries. A total of 120 autistic adults (Mage=33.58, SDage=11.67; 56M/56F/8Other) and 126 non-autistic adults (Mage=32.99, SDage=11.16; 56M/64F/6Other) were recruited, and all participants completed the Adult Behaviour Questionnaire-2 (RBQ-2A; subscales RSMBs and IS), and the University of Bath Interests Scale (UBIS; subscales degree of interest, time engaging in interests, interference and distress), and the Depression Anxiety and Stress Scale (DASS21) to measure mental health. ANOVAs were used for group comparisons and hierarchical regressions were used to explore relationships between RRBs and depression, anxiety, and stress.
Results: ANOVA results showed higher depression, anxiety, and stress scores as well as greater repetitive sensory-motor behaviours and IS in the autistic versus the non-autistic adults. Autistic adults also showed reduced interests and higher distress and interference in everyday life when unable to engage in their interests, than the non-autistic adults. Regression results showed a stronger negative relationship for the autistic group between time engaging in interests and both depression and anxiety scores, and a stronger positive relationship between the degree of interests and both depression and anxiety scores, compared to the non-autistic group. There was a stronger positive relationship for the autistic group between RSMBs and anxiety compared to the non-autistic group.

Conclusions: The greater scores in RRBs, depression, anxiety, and stress scores in autistic versus non-autistic adults are consistent with previous research showing an association between autism and poorer mental health, and with diagnostic criteria demonstrating repetitive behaviours and reduced interests. A higher degree of interest in autistic participants related to poorer mental health, which may reflect the effects of overly-intense interests. Reduced time spent on interests was associated with poorer mental health in autistic adults than non-autistic adults, perhaps reflecting the importance of time engaging in specialised interests for autistic wellbeing. These findings help to inform interventions and future research exploring the effects of RRBs, specifically of interests on mental health in autism.
Date of Award29 Mar 2023
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorChris Ashwin (Supervisor) & Hazel Went (Supervisor)


  • autism
  • Mental Health
  • RRBs
  • Autism spectrum conditions

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