Adults with autism spectrum conditions experience increased levels of anomalous perception

RESEARCH ARTICLE Adults with autism spectrum conditions experience increased levels of anomalous perception Elizabeth Milne1*, Abigail Dickinson1, Richard Smith2 1 Sheffield Autism Research Lab, Department of Psychology, The University of Sheffield, Sheffield, South Yorkshire, United Kingdom, 2 Sheffield Adult Autism and Neurodevelopmental Service, Sheffield Health and Social Care NHS Trust, Sheffield, South Yorkshire, United Kingdom * a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Milne E, Dickinson A, Smith R (2017) Adults with autism spectrum conditions experience increased levels of anomalous perception. PLoS ONE 12(5): e0177804. https://doi.org/10.1371/ journal.pone.0177804 Editor: Marina A. Pavlova, Universitatsklinikum Tubingen, GERMANY Received: December 1, 2016 Accepted: May 3, 2017 Published: May 18, 2017 Copyright: © 2017 Milne et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are hosted at Figshare at the following DOI: https://doi. org/10.15131/shef.data.4269716. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Abstract Autism spectrum condition (ASC) is characterised by differences in social interaction and behavioural inflexibility. In addition to these core symptoms, atypical sensory responses are prevalent in the ASC phenotype. Here we investigated anomalous perception, i.e. hallucinatory and/or out of body experiences in adults with ASC. Thirty participants with an ASC diagnosis and thirty neurotypical controls completed the Cardiff Anomalous Perception Scale (CAPS) and the Social Responsiveness Scale (SRS-2). The CAPS is a 32-item questionnaire that asks participants to indicate whether or not they experience a range of anomalous and out of body experiences, and to rate how intrusive and distressing these experiences are. The SRS-2 asks participants to rate the extent to which they identify with a series of 65 statements that describe behaviours associated with the autism phenotype. We found that total CAPS score was significantly higher in the participants with ASC (mean = 14.8, S.D. = 7.9) than the participants without ASC (mean = 3.6, S.D. = 4.1). In addition, the frequency of anomalous perception, the level of distraction and the level of distress associated with the experience were significantly increased in participants with ASC. Importantly, both the frequency of anomalous perceptual experiences and the level of distress caused by anomalous perception in this sample of adults with ASC were very similar to that reported previously in a sample of non-autistic participants who were being treated in hospital for a current psychotic episode. These data indicate that anomalous perceptual experiences are common in adults with ASC and are associated with a high level of distress. The origins of anomalous perception in ASC and the implication of this phenomenon are considered. Introduction Autism spectrum condition (ASC) is a pervasive developmental disorder that is diagnosed on the basis of impairments in social interaction and communication, in the presence of restricted interests and repetitive behaviours [1]. In addition to these primary symptoms, sensory issues occur frequently in ASC and there is now a wealth of empirical evidence which suggests that PLOS ONE | https://doi.org/10.1371/journal.pone.0177804 May 18, 2017 1 / 12 Anomalous perception in adults with autism spectrum conditions the majority of individuals with ASC demonstrate some form of atypical sensory behaviour. For example, one large study which reported data obtained from the short sensory profile from 291 families found that 95% of children with ASC demonstrated abnormal sensory behaviours [2]. In addition, a growing number of qualitative studies highlight sensory issues as one of the key themes of living with ASC [3]. Taking a grounded theory approach, Smith and Sharp [4] investigated the way in which atypical perception affects the lives of adults with ASC and identified heightened senses and sensory stress as commonly experienced phenomena. The term ‘atypical perception’ is frequently used to describe sensory issues in people with ASC. It describes the fact that many people with ASC have different sensory experiences compared with people without ASC. These experiences are generally defined as hyper- or hyporesponsivity to sensory stimuli, and/or alterations in the way in which sensory input is modulated and can manifest in atypical sensory behaviours such as fascination with certain sensory experiences, highly tuned senses and / or intense dislike of some sensory stimuli. A recent study that investigated the extent to which sensory issues are correlated with self-reported autistic traits in the general population found that autistic traits are also related to anomalous perceptual experiences [5]. ‘Anomalous perception’ is distinct from atypical perception as defined above, and is the term given to perceptual and hallucinatory experiences of the type that are commonly associated with psychosis, such as hearing voices, experiencing perceptual distortions, and having ‘out-of-body’ experiences. Anomalous perception is common in a number of psychiatric conditions including schizophrenia and psychosis spectrum disorders; it also occurs to a lesser degree in the non-clinical population [6, 7]. Individual variability in cortical excitability and individual variability in autistic-traits have, in two separate studies, been found to be associated with anomalous perception in the general population [5, 8]. For example, individuals who have had out of body experiences in the absence of any clinical diagnosis show increased sensitivity to high contrast black and white stripes—a phenomenon known as ‘pattern-glare’ that is considered to reflect increased cortical excitability [9]. Furthermore, in a large sample of neurotypical participants, scores on a the Autism-Spectrum Quotient [10] and scores on the Cardiff Anomalous Perceptions Scale (CAPS, [11]) were found to be moderately but significantly correlated [5]. Although this study included some individuals with a diagnosis of ASC no comparison of the extent to which anomalous perception occurred in the participants with and without a diagnosis of ASC was given [5]. Therefore it remains unclear whether or not anomalous perception occurs more frequently in individuals with ASC compared to those without. The aim of the study presented here was to measure anomalous perception in individuals with ASC and to compare this with a well-matched control group. A secondary aim was to investigate the effect of anomalous perception on adults with ASC by measuring the levels of (...truncated)