Potential of acceptance and commitment therapy (ACT) to improve outcomes in muscle disorders: a longitudinal investigation of psychological flexibility and systematic review of ACT for long-term conditions

Abstract

Muscle disorders are chronic, progressive conditions, the majority of which are without disease modifying treatments. Quality of life (QoL) is reduced in these conditions, and alternative methods, such as psychological intervention, may offer ways to improve QoL. Previous work has suggested that aberrant illness perceptions may be influential targets for psychological interventions; however, emerging evidence suggests that psychological flexibility might offer another treatment target. This thesis first presents a longitudinal investigation of the role of these two variables, alongside disability level, in explaining life satisfaction and mood measured four months later. Participants were recruited from charities and online communities, with data collected via online questionnaires. Here, illness perceptions and psychological flexibility, but not disability level, were cross-sectionally associated with all dependent variables. In prospective analyses psychological flexibility accounted for greater variance in life satisfaction and anxiety; while illness perceptions explained more variance in depression. However, after controlling for variance in time one dependent variables, psychological flexibility alone was predictive of life satisfaction and anxiety at time two. Therefore, psychological flexibility represents a possible influential target for psychological intervention in muscle disorders. Acceptance and Commitment Therapy (ACT) is a psychological intervention specifically designed to improve psychological flexibility. Subsequently, the results of the empirical study imply that ACT is worthy of trial with muscle disorders. However, there has been no comprehensive review of the use of ACT in chronic disease or long-term conditions. Therefore, Chapter 2 presents a systematic review of ACT as applied to chronic disease/long-term conditions. The aims were to collate all ACT interventions with chronic disease/long-term conditions; evaluate their quality and comment on efficacy. Ovid MEDLINE, EMBASE and Psych Info were searched, with a further search of citing articles undertaken using Google Scholar. Studies with mental health or chronic pain populations were excluded. Study quality was then rated, with a proportion re-rated by a second researcher. Seventeen studies were included, of which: eight were randomised controlled trials (RCTs), three used pre-post designs, and seven were case studies. A broad range of applications were observed (e.g. improving quality of life and symptom control, reducing distress) across many diseases/conditions (e.g. HIV, cancer, epilepsy). However, study quality was generally low, and many interventions were of low intensity. The small number of RCTs per application and lower study quality emphasise that ACT is not yet a well-established intervention for chronic disease/long-term conditions. However, there was promising evidence for certain applications: the parenting of children with long-term conditions, seizure-control in epilepsy, psychological flexibility and possibly self-management/lifestyle. The studies comprising this thesis suggest that, whilst psychological flexibility appears influential in muscle disorders, high-quality research into ACT interventions for chronic disease/long-term conditions is generally lacking. Therefore one cannot confidently generalise from existing studies that ACT will improve outcomes in muscle disorders. Thus an evaluation of ACT in the context of muscle disorders is now required. This should adhere to the methodological suggestions provided in the systematic review.