Association between depression and medication adherence in noncommunicable diseases: a narrative review

Noncommunicable diseases (NCDs), including cancer, diabetes, hypertension, cardiovascular diseases, and chronic respiratory conditions, are the leading global causes of morbidity and mortality. Depression frequently co-occurs with these conditions, and may significantly reduce medication adherence, thereby worsening health outcomes. This narrative review examines the relationship between depression and medication adherence in patients with NCDs. It also highlights the current challenges in managing this comorbidity and explores potential strategies for improving adherence outcomes. Most studies have reported a significant negative association between depression and medication adherence in diverse NCD populations. Depressive symptoms impair motivation, memory, and executive functioning, which are essential for the maintenance of treatment regimens. However, inconsistencies across studies have been observed due to variability in the measurement of depression and adherence, study design, and control of confounding factors. Despite evidence from high-income countries supporting integrated care models such as collaborative care and cognitive behavioral therapy, implementation of these models in low- and middle-income countries remains limited. Emerging strategies, including task shifting, digital health tools (e.g., mobile health apps and telemedicine), and community-based support systems, offer promising avenues for intervention. Addressing this issue requires integrated and scalable interventions tailored to local contexts. Future research should focus on longitudinal and interventional studies, particularly in resource-limited settings, to inform policies and practices.