Posture and Movement under Influence: Neurophysiological and Neurobiochemical Factors in Neurodegenerative Diseases

Abstract

Postural instability is a common and tragic symptom of neurodegenerative disorders, markedly elevating the risk of falls and morbidity. Healthcare providers must appropriately evaluate and manage postural instability in individuals with these medical conditions to avert falls and enhance quality of life. Nonetheless, the specific pathophysiological mechanisms underlying these impairments differ significantly across diseases. This study offers an extensive examination of the neurophysiological and neurobiomechanical factors influencing posture in Parkinson’s disease (PD), Multiple Sclerosis (MS), Huntington’s disease (HD), Alzheimer’s disease (AD), and Amyotrophic Lateral Sclerosis (ALS). Dopamine depletion and cholinergic dysfunction in basal ganglia circuits in Parkinson’s disease inhibit anticipatory adjustments and sensory reconfiguration, leading to rigidity and distinct sway patterns. Multiple sclerosis is characterised by conduction delays due to demyelination, exhaustion, and stiffness, resulting in increased sway amplitude and velocity. Conversely, HD entails striatal degeneration that produces involuntary choreiform movements, resulting in unpredictable and unexpected shifts in the centre of mass. Alzheimer’s disease is characterised by cortical shrinkage and cognitive-motor disruption, revealing significant impairments in sensory integration, especially with diminished visual stimuli. ALS exhibits a distinct profile characterised by the degeneration of upper and lower motor neurones, which undermines trunk control and leads to maladaptive stiffening tactics. This analysis posits that extant generic interventions frequently prove ineffective due to a failure to account for these differing mechanisms. Therefore, we propose a move towards disease-specific evaluation methodologies and customised rehabilitation strategies to effectively reduce falls and improve patient autonomy.