Self-Injurious Behaviours in Autism: A Literature Review

Self-injury is a frequent and serious problem for individuals with autism and developmental disabilities. This paper summarizes the clinical and empirical evidence pertaining to self-injury, and highlights valid theories and treatment options. Unlike most reviews of self-injury, the present one pays particular attention to the impact that research has made within the field of autism treatment. The importance of prospective large-scale research is stressed to support the development of treatments that should alleviate or even prevent the primary causes of self-injurious behaviour. This review aims to impart readers with an unambiguous conceptualization of self-injury and hopes to stimulate further research within the field. There is little debate over the seriousness of self-injurious behaviour (SIB) in individuals with autism and developmental disabilities. There exists, however, considerable discussion over the etiology, functions, and treatment of SIB. This is problematic since proposed therapies are often shaped by the hypothesized cause of the problem (Matson, 1988), and are inherently linked to issues of human rights (Rothenberger, 1993a). Thus, a literature review examining the association between self-injury and autism is both clinically and academically relevant. Unfortunately, there has been little theoretical or empirical investigation of self-injury and autism in particular. This is perhaps due to the considerable co-morbidity of autism in developmentally disabled populations, and further, to the fact that selfinjurious behaviours in individuals with autism and individuals with developmental disabilities without autism seem to be functionally similar (Oswald, Ellis, Singh & Singh, 1994). Consequently, while this review is meant to highlight SIB in individuals with autism, it also examines studies of SIB in the field of developmental disabilities in general. By summarizing the leading taxonomies, providing current data on the specificity of SIB in autism, and highlighting clinically and empirically validated etiological theories and treatments, this review hopes to provide clinicians and researchers with a practical and clear conceptualization of self-injury. Definition and Classification It is important to review and arrive at consensus over the definition and taxonomy of SIB, in order to generalize findings across studies and design appropriate treatments. Self-injurious behaviours can be seen as "a class of behaviours, often highly repetitive and rhythmic, that result in physical harm to the individual displaying the behaviour (Fee & Matson, 1992, p. 4). " Moreover, such behaviours should occur without an apparent intent of wilful self-harm. It is important to distinguish between behaviours, such as suicide, that are associated with intentional desires to cause selfharm, and SIB found in individuals with developmental disabilities, which may occur in association with biological pathologies or are more a result of environmental factors. Intentionally self-harming behaviours are also often referred to as selfmutilation, self-destructive, or masochistic behaviours (Fee & Matson, 1992). Self-injurious behaviours are often placed on a continuum with repetitive sterotypies, and have been suggested to only differ at the moment of injury (Jones, 1987). In fact, recent reviews of repetitive behaviours in autism place SIB within its broad class (Turner, 1999). Self-injurious behaviours can range from severe, life-threatening injuries to less directly damaging cases. In their summary of SIB taxonomies, Fee and Matson (1992) place numerous examples of SIB on a continuum ranging from mild to severe, reproduced in Figure 1. For example, cases of ruminative vomiting (Lang & Melamed, 1969) and uncontrollable climbing (Risley, 1968) are considered SIB since they can indirectly cause harm and are treated with the same behavioural techniques used for other injurious behaviours (Murphy & Wilson, 1985). Figure 1: Self-injurious behaviours on a continuum from mild to severe Mild forms Most severe The classification of SIB has occurred on the basis of both conceptual and empirical grounds. In terms of diagnosis, the DSM-IV (American Psychiatric Association [APA], 1994) classifies SIB as Stereotypic Movement Disorder (formerly Stereotypy/Habit Disorder) for individuals with mental retardation, but not for WEISS 130 · Head rubbing · Occasional contact with surface when rocking · Finger sucking · Nail picking · Thigh slapping · Orifice poking · Eye poking · Hair pulling · Self-scratching · Self-pinching · Chronic rumination · Frequent arm biting · Violent head banging individuals with a pervasive developmental disorder (PDD). In the latter case, selfinjury is thought to be better explained by the PDD diagnosis. As will become evident in the following section on the prevalence of SIB in individuals with PDD and mental retardation, the differential inclusion of one population may be empirically unwarranted. Jones (1987) has proposed a conceptual taxonomy based on the frequency of SIB, dividing behaviours into two subgroups. The first subgroup, deemed stereotyped SIB, is comprised of behaviours that are repetitive, and occur with little variation and high frequency. In contrast, self-aggressive behaviours manifest at a much lower rate and may possess adaptive functions. While clinically relevant, there are a number of serious contentions with such a distinction. First, there is little consensus over what quantitative value differentiates ‘high’ from ‘low’ frequencies (and ‘medium’ frequency for that matter). Moreover, SIB frequency and severity may vary depending on particular contexts and environmental demands (Oswald et al., 1994). Thus, a behaviour that may be considered stereotyped may also be considered selfaggressive in a different context. It seems that a conceptual taxonomy is only as valid as its empirical basis. For example, Schroeder, Mulick and Rojahn (1980) developed a useful nosology based on epidemiological data (Schroeder, Schroeder, Smith & Dalldorf, 1978) and a review of 75 studies. Findings indicated two main groups of SIB (as outlined in Table 1) which seemed to differ on the basis of whether or not the behaviour was maintained by social reinforcement. On the one hand, social SIB seemed to occur more often in a social setting, were directly self-injurious, and were associated with stereotyped behaviours and other behaviour problems. On the other hand, non-social SIB seemed to occur less frequently and were all consumatory behaviours. Table 1: Social and Non-social Self-Injurious Behaviour Classifications (Schroeder, Mulich & Rojahn, 1980) Social Non-social Head-banging Stuffing orifices Self-biting Mouthing Self-scratching Sucking Gouging Rumination Pinching Copophagy (ingestion of feces) Hair-pulling Aerophagia (ingestion of air) Polydipsia (excessive fluid intake)