Prevalence of autism is constant across the life span; if 1 in 100 children experience autism worldwide, then 1 in 100 adults experience autism worldwide (Baxter, 2014; Brugha, 2012). But, adults with autism attract little attention from researchers. An Australian Cooperative Research Centre (Autism CRC, 2014) recently estimated that only 1% of the international autism research agenda focuses on adults.
Adults with autism who also experience intellectual disability may have distinct clinical presentations and needs. They are likely to experience poorer long-term health and social outcomes compared with those without intellectual disability (Howlin, 2012). In particular, ‘challenging behaviour’ may increase social isolation, and importantly, reduce access to quality health care.
National Institute for Health and Clinical Excellence (NICE) guidelines state that clinicians should look at the wider causes of challenging behaviour in adults with autism before they administer other interventions (NICE, 2012). Challenging behaviour may be an individual’s way to communicate that they are in pain or have unmet medical needs. But, medication is often the first step clinicians take to treat challenging behaviour in this group.
Unfortunately, NICE guidelines don’t exist for adults with autism and intellectual disability and there has been very little research about the treatment of challenging behaviours in this group. In this study, recently published in Research in Autism Spectrum Disorders (Sawyer et al. 2014), researchers from the University of Toronto took steps to better understand the efficacy of pharmacology for challenging behaviours in adults with autism and intellectual disability.
Using a systemic review strategy, the authors explored three databases for English-language studies of interventions targeting challenging behaviour among adults with autism and intellectual disability. In this study, authors describe challenging behaviour as jeopardising an individual or excluding them from community involvement.
Using this strategy, the authors were unable to find any studies involving participants with both autism and intellectual disability. So, they included studies where all participants experienced autism and at least some experienced intellectual disability, and they took note of the statistics included for this subgroup.
The authors assessed study quality using The Cochrane’s Collaboration tool for assessing risk of bias in randomised trials. They also looked at study characteristics, outcomes and interventions.
The authors decided only seven articles should be included in the review. Of these articles, four were written by the same author, and two articles arose from the same study. Given this small number, the authors conclude that research on the pharmacological treatment of adults with autism and intellectual disability is remarkably limited.
Five medications were included in the studies:
- sertraline (SSRIs),
- clomipramine (anti-depressants),
- ziprasidone (atypical antipsychotics).
Only risperidone and fluvoxamine were subjected to randomised control trials (considered to offer the highest level of evidence).
The other studies used case series or open label trials. All medications showed reductions in challenging behaviours.
Risperidone provided the best evidence for effective short- and long- treatment across repetitive, self-injurious and aggressive behaviours.
There is not enough research exploring the efficacy of pharmacological and psychosocial interventions for adults with autism. No studies of interventions among adults with autism and intellectual disability exist. Without high quality studies, clinicians have little guidance about treatment approaches for challenging behaviour in this group.
Strengths and limitations
The authors have worked hard to ensure the high quality of their systematic review. In using The Cochrane Collaboration tool to consider issues of bias, they critiqued study quality well. The authors offer clear data on the efficacy of medications across three aspects of challenging behaviour as well as tolerability of each medication. This structured assessment may be useful as a ‘one-stop-shop’ for clinicians/practitioners. It’s important to note, however, that although the authors found that Risperidone provided the best evidence for treatment, given the small number of studies available, the evidence base for this medication remains weak.
The review was limited by the small number of eligible studies and the poor methodological rigour of most of the included studies. The variety of outcome and interventions (e.g., RCTs, open label trials, case series) across the studies meant that statistical data synthesis was impossible. Among the six studies, four were categorised as ‘high risk of bias’ across over half of the measures used for assessment.
The review authors emphasised the importance of understanding the biological, psychological and psychosocial causes of challenging behaviour. However, the studies reviewed did not provide enough detail to assess whether they were treating challenging behaviour, or anxiety or simply noting the sedating effects of the medication. In other words, the studies offered little in relation to understanding the ‘aetiology’ of challenging behaviours.
Authors offer important directions for future studies. They encourage researchers to better understand the causes of challenging behaviour. Medical interventions for challenging behaviour may not help if someone has an untreated medical illness or is in pain. The authors also note the need for tools that help carers monitoring treatment efficacy and adverse effects, especially for those individuals without verbal communication.
This way, we won’t have to rely on opinion to assess whether behaviour has changed. However, such tools would be difficult to develop and validate, and might not be available before other pharmacology interventions progress.
Such is the difficulty of research in this field – we must work well with ‘what we’ve got’, while continuously pushing for higher quality tools that allow for better evidence.
It is clear that more research is needed to help practitioners to make evidence based decisions when working in already challenging circumstances. No studies were found offering guidance about people with autism and intellectual disability.
This finding is representative of the evidence gap that exists for this group and the health professionals who support them.
Sawyer A, Lake JK, Lunsky Y, Liu SK, Desarkar P. Psychopharmacological treatment of challenging behaviours in adults with autism and intellectual disabilities: a systematic review. Research in Autism Spectrum Disorders 2014; 8(7): 803-813 [abstract]
Autism Cooperative Research Centre (Autism CRC) Ltd. Program 3: Adulthood. Available at: http://www.autismcrc.com.au/research-programs/adulthood.
Baxter, AJ et al. (2014). The epidemiology and global burden of autism spectrum disorders. Psychological Medicine First View: 1-13.
Brugha, T. S., S. McManus, J. Bankart, F. Scott, S. Purdon, J. Smith, P. Bebbington, R. Jenkins and H. Meltzer (2011). Epidemiology of autism spectrum disorders in adults in the community in England. Archives of General Psychiatry 68(5): 459-466.
NICE. Autism: Recognition, referral, diagnosis and management of adults on the autism spectrum. Clinical guideline 142. http://guidance.nice.org.uk/ck142
Piven, J., P. Rabins and A.-I.-O. A. W. Grp (2011). Autism Spectrum Disorders in Older Adults: Toward Defining a Research Agenda. Journal of the American Geriatrics Society 59(11): 2151-2155.