Insistence on sameness, repetitive negative thinking and mental health in autistic and non-autistic adults.

Lay abstract: Autistic people are more likely to have mental health problems than non-autistic people. We know that having repetitive and negative thoughts can contribute to multiple mental health problems such as depression and obsessive-compulsive disorder. Autistic people often do the same behaviours repetitively, and they may also have more repetitive thinking styles. This could contribute to higher rates of mental health problems in autistic people. In this research, we wanted to find out if higher rates of repetitive behaviours contributed to depression and anxiety, and whether this relationship was because of repetitive negative thinking. We asked three groups of autistic adults to take part in the research. Sixty-seven autistic clinical participants were recruited from clinical settings and had moderate depression. Fifty-four autistic community participants and 66 non-autistic community participants were recruited from community settings. All participants completed measures of repetitive behaviours; a measure of anxiety and depression; and two measures of repetitive negative thinking (ruminating and obsessing). Autistic community participants had significantly higher repetitive behaviours, rumination and obsessing scores than non-autistic community participants. We found that higher rates of repetitive behaviours contributed to more repetitive thinking (obsessing and ruminating), which contributed to higher rates of depression and anxiety. The higher rates of repetitive negative thinking found in autistic individuals may contribute to higher rates of mental health problems in this group. Mental health assessments and interventions for autistic people should therefore consider the role of multiple forms of repetitive negative cognition and behaviour, which cut across diagnostic categories such as anxiety, depression and obsessive-compulsive disorder. These should be considered when aiming to understand why individuals develop mental health conditions and why these conditions persist.