Factors associated with oral nutritional behaviours in Neurodegenerative Disorders of the motor system: A systematic review

Background. Excessive weight loss is common in Neurodegenerative Disorders of the motor system (NDMS; e.g., Parkinson’s disease, Amyotrophic Lateral Sclerosis) and is associated with poor health outcomes. Weight loss may arise from disease activity directly (e.g., muscle wastage) and altered oral nutritional behaviours (ONBs). However, little is known about the key factors associated with these oral nutritional behaviours (ONBs) or outcomes.Methods. A systematic search of electronic databases identified papers examining factors (e.g., knowledge, beliefs) associated with ONBs/outcomes (e.g., swallowing, calorie intake, weight) in NDMS. The COM-B model was used to interpret the narrative review and synthesis. Results. Sixty-one quantitative papers and four qualitative papers were included. The most consistent correlates of poorer ONBs/outcomes were disease characteristics including severity, duration, and dysphagia (Capability–Physical). Cognitive impairment and lack of knowledge about high calorie diets (Capability–Psychological) and the absence of caregivers (Opportunity–Social/Physical) were related to poorer ONBs/outcomes. Patients’ desire for independence was related to better outcomes whereas low perceived need and low response efficacy of a high calorie diet were related to poorer ONBs/outcomes (Motivation–Reflective). Eating habits, depression, and lack of appetite related to poorer outcomes (Motivation–Automatic).Conclusion. Quantitative studies focused on the impact of disease characteristics on nutritional outcomes, whereas qualitative studies explored the impact of NDMS on ONBs in the context of everyday life. Together, these findings highlight that interventions to prevent weight loss in people with NDMS should target their capabilities, opportunities and motivations and be tailored to their disease stage and living circumstances.