Factors influencing implementation of an Alzheimer’s disease blood test among UK old age psychiatrists: mixed-methods study using the theoretical domains framework

INTRODUCTION: Only 6% of UK memory services meet Alzheimer's disease (AD) biomarker access guidelines, limiting psychiatrists' experience. Emerging AD blood biomarker (BBM) tests will potentially expand access. Exploring implementation barriers and enablers a priori can inform rollout strategies. This study examined current clinical practises, barriers and enablers to implementation and potential interventions to support implementation. METHODS: In November 2024, Royal College of Psychiatrists Old Age Psychiatry Faculty members (n = 172) participated in an online survey and four focus groups (n = 16 participants), informed by the Theoretical Domains Framework (TDF) and Behaviour Change Wheel. Demographic data were summarised descriptively. Mean (SD) belief statement scores for TDF domains and percentage agreement were calculated. Multiple linear regression examined associations between TDF domains and intention to use BBMs. RESULTS: Respondents were mainly consultants in England; <33% had used biomarkers. Key barriers to use were: 'Knowledge,' 'Environmental Context and Resources' and 'Goals.' Enablers included: 'Behavioural Regulation,' 'Social Influences' and 'Intention.' Mixed enablers/barriers included: 'Beliefs about Consequences', 'Optimism' and 'Social/Professional Role & Identity'. In regression analyses, 'Memory, Attention and Decision Processes' (B = 0.44, 95%CI 0.20-0.68), 'Beliefs about Consequences'(B = 0.45, 95%CI 0.11-0.78), and 'Social Influences' (B = 0.24, 95%CI 0.04-0.44) were positively associated with intention, while 'Optimism' (B = -0.31,95% CI-0.58 to-0.04) and 'Emotion' (B = -0.33, 95%CI -0.60 to-0.06) were negatively associated. Key interventions were 'Guidelines' (e.g. appropriate use criteria) and 'Environmental Restructuring' to expand resources and re-organise pathways. DISCUSSION: A complex interplay of barriers and enablers influences AD BBM implementation. Interventions targeting clinician, service and policy levels are required to support their introduction.