The Infinity Formulation: how transdiagnostic behaviours and endeavours for behavioural change serve to maintain co-morbid mental health presentations

Treatment recommendations for mental health are often founded on diagnosis-specific models; however, there are high rates of co-morbidity of mental health presentations and growing recognition of the presence of ‘transdiagnostic processes’ (cognitive, emotional or behavioural features) seen across a range of mental health presentations. This model proposes a novel conceptualisation of how transdiagnostic behaviours may maintain co-morbid mental health presentations by acting as a trigger event for the cognitive biases specific to each presentation. Drawing on existing evidence, psychological theory and the author’s clinical experience, the model organises complex presentations in a theory-driven yet accessible manner for use in clinical practice. The model offers both theoretical and clinical implications for the treatment of mental health presentations using cognitive behavioural approaches, positing that transdiagnostic behaviours be the primary treatment target in co-morbid presentations. Key learning aims (1) To understand the strengths and limitations of existing transdiagnostic CBT formulation models. (2) To learn about a novel, transdiagnostic and behaviourally focused formulation for use in clinical practice. (3) To understand how to use the tool in clinical practice and future research.