Adherence to Parkinson's disease medication: A case study to illustrate reasons for non-adherence, implications for practice and engaging under-represented participants in research

Parkinson's disease (PD) is a progressive neurodegenerative disease which primarily presents with the core symptoms of rigidity, postural instability, tremor, and bradykinesia. Non-adherence to prescribed PD treatments can have significant ramifications, such as poor symptom control and greater disease burden. Reasons for poor adherence are multifaceted, particularly when medication regimens are complex and often based on perceptual and practical barriers. Additionally, engaging fully non-adherent patients in research is challenging since they may have dropped out of service provision, yet their contribution is vital to fully understand the rationale for non-adherence. This paper aims to present a case study on the perspectives of one person with PD, a participant in a previously published qualitative study investigating the barriers and facilitators to medication adherence in PD. In this paper, the participant's diagnostic journey is described, and experiences of medical consultations are summarised to explain their reasons for not adhering to any of the standard UK PD treatments prescribed. The participant's preferences for using Vitamin B1 (thiamine) injections to manage the symptoms are reported and the rationale for doing so is discussed. We consider the case through the lens of a behavioural science approach, drawing on health psychology theory, the Theoretical Domains Framework (TDF), to inform the review and the practical challenges faced when analysing the data for this participant. Implications for pharmacy practice, in particular, are also put forward with view to ensuring that patients such as Mr. Wilkinson are provided with the opportunity to discuss treatment choices and self-management of long-term conditions such as PD. We also discuss the importance of reaching under-represented members of the population in medication adherence research, which embraces the principles of equality, diversity, and inclusion in research.