Methodological and Conceptual Advances in Understanding Psychological Flexibility as a Modifiable Protective Factor for Suicidal Thoughts and Behaviours

Abstract

Suicide is a global public health issue. Cross-nationally, many people experience suicidal thoughts and behaviours (STBs). Much is known about the risk factors of STBs; for example, as depicted by the Integrated Motivational Volitional (IMV) Model. However, modifiable protective factors remain relatively under-researched. Psychological factors which underlie existing intervention packages, such as psychological flexibility. Psychological flexibility is purported to be the therapeutic process of change underlying an existing intervention package – Acceptance and Commitment Therapy. Broadly, this PhD explored whether psychological flexibility had a potentially protective role for STBs. Four original studies designed this evidence gap were conducted. A large, three-wave longitudinal survey with adults from the online general population laid the conceptual groundwork for this thesis on proximal risk. Testing the IMV model cross-sectionally and longitudinally using structural equation modelling confirmed that the IMV’s central path was empirically sound. The full model with motivational moderators showed poor model fit, perhaps explainable by methodological and statistical challenges discussed. Psychological flexibility, particularly valued actions and behavioural awareness were moderate-to-strong cross-sectional and longitudinal correlates of proximal risk factors, and possibly volitional moderators. The natural stability of the constructs suggests that experimental, intervention work is needed to fully test the theorised effect of psychological flexibility as a protective factor for proximal risk of STBs. Study 2 examined the acceptability of five values clarification exercises (VCEs) using an online randomised, active-controlled experimental trial. Adults with recent experience of suicidal thoughts provided invaluable open-ended feedback on the acceptability of the VCEs, informing a tailored, single-session VCE. Study 2 also found preliminary evidence that the VCEs improved state value clarity, the therapeutic process of change. Study 3 evaluated the short-term effects of the tailored VCE using 4 a single-case experimental design (SCED) with ecological momentary assessment (EMA) technology. Individual- and group-level analyses suggested largely equivocal results for suicidal thoughts and value clarity/actions. Study 4, an EMA item validation study, confirmed that low convergent validity may explain these equivocal findings. Moreover, participants experienced some degree of momentary reactivity to the EMA item-sets throughout the day, highlighting potential implications for understanding confounding effects in intervention EMA-informed SCED studies. Conceptually, the longitudinal evidence provided throughout this thesis means that we are one step closer towards understanding the protective role of psychological flexibility (in particular, value clarity and action). The acceptability data on the experience of an online, self-guided single-session VCE for adults at-risk of suicide may be particularly relevant for clinicians. Methodologically, the feasibility and measurement challenges discussed throughout this thesis highlight important considerations for future research. Replication is needed prior to scaling up this work. Going forward, researchers are encouraged to work collaboratively with people with lived experience to co-produce effective online values-based interventions.