Clinical Applications: Neurodegenerative Disorders and MS

Parkinson's disease (PD) and Alzheimer's disease (AD) are the two most common neurodegenerative disorders. Multiple sclerosis (MS) is the most common demyelinating disorder. Although there are strong inflammatory components to multiple sclerosis, it is clear that the disease also has a strong neurodegenerative component. Combined these three disease processes affect more than 6 million Americans in countless more people around the world. The cost related to care and treatment for these patients are staggering both in terms of human suffering and the financial burdens on the patient and families as well as national health care systems. In the US alone, some estimates suggest that over $100 billion is spent yearly in terms of direct and indirect health-care costs. The total amount spent on neurodegenerative processes, particularly for AD and PD, is expected to rise given the aging demographic in the US and other countries. AD and PD have been studied extensively using a variety of imaging techniques. Conventional MR imaging has play a primary role in excluding other neurologic abnormalities. Multiple sclerosis has been extensively studied using conventional MR imaging techniques. Unlike AD and PD, conventional MR imaging plays an important role in the diagnosis of MS. Newer imaging techniques such as diffusion tensor imaging and functional MRI offer the potential for improved diagnosis, better understanding of the underlying mechanisms, improved disease monitoring and guidance of therapy PD, AD, and MS The majority of MR imaging research directed towards Alzheimer's disease has focused on morphologic measurements. There's a large body of information documenting morphologic changes related to Alzheimer's disease, particularly, findings of hippocampal and cortical atrophy. A multitude of quantitative methodologies have been proposed for assessment of atrophy. Overall findings suggest that morphologic measurements are useful for the diagnosis of AD, sensitive to early changes in mild cognitive impairment and useful for monitoring disease progression. (1-8) More recently, cognitive impairments associated with Alzheimer's disease have been studied using functional MRI. There are significant underlying issues related to task performance, evaluation of functional activation in the face of atrophy and age-related changes in blood flow and vascular coupling to be considered in studying Alzheimer's patients. Despite these considerations, an increasing body of literature has accumulated over the last several years demonstrating fMRI activation changes in Alzheimer's disease utilizing a variety of tasks including memory, verbal and semantic tasks. Findings suggest decreased activation in the hippocampal regions of patients with mild cognitive …