INTRODUCTION

Research in the field of dementia has increased exponentially over the last 30 years, leading to a wealth of information on the epidemiology, psychology, neuropathology, biochemistry and genetics of Alzheimer's, Parkinson's and other neurodegenerative diseases. Interdisciplinary approaches have begun to combine the information gathered from the various fields of study into theories regarding the etiology, prevention and treatment of these disorders. This chapter will focus on the neuropathology of several neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and progressive supranuclear palsy, diffuse Lewy body disease, Huntington's disease, corticobasal degeneration, Pick's disease and prion disease. Vascular dementia is beyond the scope of this chapter and will not be discussed. The currently known neuropathological changes will be discussed in relation to the cognitive impairments of each neurodegenerative disease. Clinical and neuropathological criteria for the various neurodegenerative diseases are presented in Tables 3.1 and 3.2.

Due to the considerable overlap of clinical and neuropathological symptoms among neurodegenerative diseases, guidelines have been published to aid in the collection of information important for an accurate diagnosis. The American Academy of Neurology has recommended the following diagnostic tests be performed on patients with dementia to rule-out potentially treatable disorders: complete blood cell count, serum electrolytes, serum glucose, blood urea nitrogen, serum creatinine, liver function tests, syphilis serology and serum vitamin B12 level (Lanska 1996). Although in most clinical settings, detailed medical and neuropsychological information is often not gathered on each patient, collection of such data in research programs is important for providing clues to the causes and progression of various types of dementia.