Evidence and Opportunities for Studying Sensorimotor Dysfunction Beyond Supratentorial Structures in Alzheimer’s Disease

Alzheimer’s disease (AD) is a debilitating neuropsychiatric disease marked by cognitive decline, but also somatosensory/motor dysfunction. No cure has been found thus far, which prompts the emphasis on both early detection and treatment of its neurodegenerative symptoms. Although the dominant narrative in AD research has focused on supratentorial structures and cognitive symptoms, there is sufficient evidence to support the role of infratentorial structures (cerebellum, brainstem, and spinal cord) that contribute to sensorimotor pathology. In this review, we discuss evidence of motor impairments in AD and how abnormalities in infratentorial structures might contribute to it. Existing literature implicates fine motor dysfunction, gait issues, agraphia, dysphagia, and other motor issues in most AD patients, some even at preclinical stages. We also found considerable evidence of cellular pathology and atrophy in the spinal cord, cerebellum, and brainstem in many AD patients. We posit that pathology in these infratentorial structures contributes, at least in part, to sensorimotor dysfunction in AD. Several important questions remain unanswered on these topics. Further research will improve our understanding of AD and contribute to the discovery of biomarkers for early and better diagnosis, prognosis, and tracking progression of this dangerous disease.