As a consequence of the shift in service delivery from institution to community, there has been an increasing amount of research focussing on the mental health needs of this population. One of the important outcomes of the research has been the recognition of people with an intellectual and/or developmental disability suffering from a concomitant mental health disorder. Anxiety and depression are the most common mental health disorders experienced by people with an intellectual and/or developmental disability.
There is a plethora of studies endorsing the evidence based practices of cognitive behaviour therapy (CBT) to treat these mental health disorders in the general population, yet there remains a conspicuous lack of research related to people with an intellectual and/or developmental disability with concomitant mental health disorder. Over the past two decades, there have been increasing studies on prevalence, diagnostic issues, assessment and treatment interventions. Despite this, there is a paucity of research examining the use of CBT to treat mental health disorders experienced by adults with an intellectual and/or developmental disability.
Whilst some studies of CBT interventions have been promising, they are largely based on weaker research design such as uncontrolled trials and case study approaches. Methodologically sound, randomised, control trials have been largely confined to treatment of anxiety/anger in children with autism spectrum disorder (Chalfant et al., 2007; Sofronoff et al., 2005, 2007) and the treatment of anger problems in adults with an intellectual disability (Taylor et al., 2002; Willner et al., 2002). Access to participants is affected by lack of detection, use of tools with poor psychometric properties, and diagnostic overshadowing. Furthermore, carers are more likely to consider the person’s behaviour within a challenging behaviour framework rather than a mental health framework. Hence, people with an intellectual and/or developmental disability are not likely to be referred to mental health services.
Prevalence rates for mental health disorder are estimated to be within 30-50 percent and most epidemiological studies suggest this figure remains an underestimate (Borthwick-Duffy, 1994; Cooper, 1997; Reiss, 1990; Smiley, 2005). Given the increased risk of mental health disorders and lack of evidence based treatments, people with an intellectual and/or developmental disability suffering from depression or anxiety have limited access to appropriate assessment and treatment, and remain under serviced.
There have been studies supporting the use of CBT interventions based on two approaches, cognitive deficit (Meichenbaum, 1977) and/or cognitive distortion (Beck, 1976) models (Anderson & Kazantsis, 2006; Dagnan & Chadwick, 1997, Dagnan & Jahoda, 2006; Esbensen & Benson, 2004; Lindsay, 1999; McCabe, McGillivray & Newton, 2006; Sofronoff et al, 2005; 2007; Ooi et al., 2008). Considering the methodological and treatment approaches of these previous studies, the current research examined the effectiveness and feasibility of applying cognitive behaviour therapy (CBT) to treat anxiety and/or depression in people with an intellectual and/or developmental disabilities with a concomitant mental health disorder.
A case study design was adopted in this research for three reasons. Firstly, there were anticipated problems accessing and recruiting participants to this study. Secondly, this design provides opportunities to examine the process and clinical issues of implementing CBT intervention to this population. Thirdly, the CBT interventions available in the literature lack adequate evidence or were not appropriate for the sample. For the purposes of this study, people with an intellectual disability and/or people with autism spectrum disorder (ASD) were included.
The participants were offered treatment at a community clinic where the author worked and delivered clinical psychology services. Prior to the intervention, the participants were diagnosed by their treating psychiatrist using DSM-IV-TR criteria and the diagnosis was confirmed with the Diagnostic Manual –Intellectual Disability (NADD, 2007) for participants with intellectual disability. Furthermore, medication remained unchanged throughout the course of the treatment. Individually, the participants were offered a CBT intervention spanning between 14 and16 weeks after they were assessed for suitability to engage in this form of treatment. Each study consisted of comprehensive assessments prior to commencement of treatment intervention and outcomes were measured on self-report and informant based tools. Each participant was re-assessed three months after the completion of the treatment.
Chapter 2 was a single case study that examined the assessment, treatment, and outcomes of a 33-year-old man with an intellectual disability and schizophrenia who presented with clinically significant anxiety and depression symptoms. This man was offered an intervention drawn from principles of the Coping Strategy Enhancement (CSE) (Yusupoff & Tarrier, 1996) and modified CBT from previous studies (Haddock et al., 2004; Hatzipetrou & Oei, 2010). This study incorporated a multiple baseline design and the participant was seen weekly for one hour over 16 weeks. Self-report and carer informed measures were collected prior, during, and at the end of the treatment. Three months later, the same measures were collected. The results revealed a reduction in anxiety and depression reported during the course of the treatment despite the persistent and significant positive symptoms. Furthermore, the participant reported increased confidence in managing anxiety and depression and developed simple and effective coping skills. These clinical outcomes were sustained over the course of three months post treatment.
Chapter 3 presented a single case study examining the efficacy of cognitive behavioural therapy for the reduction of psychological distress experienced by a 17-year-old male with Asperger's Disorder and major depression. The treatment consisted of CBT strategies utilised in previous research (Attwood, 2004; Cardaciotto & Herbert, 2004; Kendall, 1994, Reaven et al., 2008; Sofronoff, 2005; Ooi et al., 2008) to treat anxiety in children and young adolescents with autism spectrum disorder. This intervention consisted of affective education, cognitive restructuring, and enhancement of social skills and coping strategies. The results of this intervention were two fold. There was a spontaneous reduction in the frequency of physical aggression, self-harm, and utterances reflecting erroneous cognitions. Secondly, the results revealed decreases in the reported symptoms of depression and anxiety which had been sustained at three months post treatment.
Chapter 4 provided the study which examined the effectiveness of CBT to treat three female adults with an intellectual disability and major depression. Each participant underwent assessment and individualised treatment at a community clinic. The carer and self report measures were collected throughout the treatment phase, end of treatment, and three months later. The participants were offered a CBT intervention over the course of 14 weeks. The design of the study was multiple baseline and the participants completed self-report measures of anxiety and depression at each weekly session. The results of this intervention revealed two of the three participants experienced fewer and less severe symptoms of depression and anxiety at the completion of the treatment. These treatment gains were maintained at three months post treatment. One participant reported little improvement over the course of the treatment yet the carers observed subtle improvements in participant’s coping responses and self esteem.
Chapter 5 presented a single case study involving a 53-year-old Caucasian man who was referred to the study due to his diagnosis of intellectual disability and paranoid schizophrenia. Whilst accepted to the program, the pre-treatment assessment revealed a failure to meet criteria for an intellectual and/or a developmental disability. Despite a Full IQ Score of 65, these significant cognitive impairments appeared to be associated to chronic schizophrenia, rather than an intellectual disability. However, this case study was retained in the research due to its relevance to the previous three studies. Importantly, it provides an opportunity to demonstrate the application of CBT interventions to people with cognitive impairments arising from chronic and severe mental illness such as schizophrenia. He participated in weekly sessions containing CBT interventions based on Coping Skills Enhancement (CSE) (Yusupoff & Tarrier, 1996) over the course of fourteen weeks. He demonstrated increased confidence in applying coping strategies and less self reported anxiety and depression. Importantly, this study supported the use of CBT interventions to treat people with significant intellectual impairments experiencing co-morbid mental health disorders.
Together, the studies demonstrated the feasibility and effectiveness of cognitive behaviour therapy to treat anxiety and depression in people with an intellectual and/or developmental disabilities with a concomitant mental health disorder. All participants, with the exception of one, experienced reductions in self-reported anxiety and depression over the course of the interventions. Whilst these findings were encouraging, they were not conclusive or generalisable. There were inherent problems in conducting research with this population, including difficulties in identifying and recruiting participants, absence of evidence based CBT interventions, and paucity of randomised control trials in the literature. Clinically, people with an intellectual and/or developmental disability possess cognitive, social skill, and communication impairments that can impede the application of CBT intervention. However a small, growing body of literature demonstrates the effectiveness of this intervention and the need to pursue further research.