Relational processes of Non-Suicidal Self-Injury (NSSI): A review of the evidence and a brief Cognitive Analytic Therapy-informed intervention

  • Kelly-Marie Peel-Wainwright

Student thesis: Doctor of Clinical Psychology


The current thesis investigates the relational processes of non-suicidal self-injury (NSSI) and evaluates a pilot, brief Cognitive Analytic Therapy (CAT) informed intervention for those who engage in NSSI. The thesis is presented as three papers: 1) a systematic review of the literature; 2) an empirical study evaluating the intervention; and 3) a critical appraisal of the overall research process. The systematic review (Paper 1) was a qualitative meta-synthesis aimed to investigate the proximal interpersonal processes (such as triggers, causes or precipitating factors) of NSSI, from first-hand accounts of those who engage in the behaviour. A comprehensive search was conducted and 25 papers were included in the review. The synthesis revealed two overarching themes: ‘Challenging interpersonal experiences’ and ‘Getting needs met’. The synthesis provided a nuanced understanding of interpersonal processes of NSSI and clinical implications include the implementation of relational psychological approaches to support those who engage in NSSI. The empirical study (Paper 2) describes the qualitative evaluation components of a larger Randomised Control Trial: Cognitive Analytic Therapy for the Containment of Self-Harm (CATCH). Whilst the larger trial broadly explored feasibility of this ultra-brief intervention for individuals who engage in NSSI, the current study specifically aimed to evaluate the acceptability of CATCH from the perspective of those who engaged in the study. A secondary aim was to investigate the acceptability of the broader research process. A small-scale Randomised Control Trial was conducted and 14 participants were randomised into either the CATCH plus Treatment-as-Usual (TAU) or TAU alone condition. Thirteen participants then engaged in qualitative interviews regarding their experiences. Four overarching themes were found: ‘Pre-participation experiences’, ‘Acceptability of CATCH’, ‘Acceptability of the research’ and ‘Relational factors’. Overall, participants generally found CATCH and the broader research process acceptable to engage with. Results suggest that a further, larger scale evaluation of CATCH is indicated. Finally, the critical appraisal (Paper 3) provides an in-depth evaluation of the entire research project. This includes investigation into decision-making processes, the challenges of conducting research and the relative strengths of the thesis. A brief CAT-informed reformulation of the researcher’s experiences and personal reflections is presented.
Date of Award31 Dec 2020
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorPeter Taylor (Supervisor) & Richard Brown (Supervisor)


  • Cognitive Analytic Therapy
  • CAT
  • Interpersonal
  • Non-suicidal self-injury
  • NSSI

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