Alzheimer's disease (AD) is the most common neurodegenerative disorder encountered by the practicing geriatrician. However, a sizable number of other neurodegenerative diseases will be seen in a typical practice, rendering a working knowledge of these disorders critical for practicing clinicians. This chapter provides an overview of the more common neurodegenerative disorders with emphasis on those that influence behavior and cognition early in the course. We begin by reviewing the clinical approach to neurodegenerative cognitive disorders and then review the clinical presentation, epidemiology, and examination findings of the more common neurodegenerative syndromes. We attempt to link clinical presentation to anatomy and neuropathology whenever possible.
The evaluation of neurodegenerative disorders is multifaceted, requiring careful attention to the cognitive, behavioral, and motor history combined with a comprehensive neurological examination aiming to identify the brain regions involved. Isolating anatomy in patients who present with slowly progressive neurodegenerative disorders greatly facilitates the determination of the correct diagnosis.
Emphasis should be placed on the earliest presenting symptoms, whether cognitive, behavioral, or motor in origin. These early features may be critical to the identification of the pathological substrate. As diseases progress, signs and symptoms merge between the different disorders, making diagnosis more difficult. An early history of repeated falls, for example, should warrant concern for progressive supranuclear palsy (PSP) or vascular dementia; although most dementias are associated with basal ganglia involvement later in their disease course, diminishing the value of falls for diagnosis. Likewise, inappropriate behavior and disinhibition are commonly seen in patients with advanced dementia syndromes regardless of disease etiology. However, when these findings are a prominent presenting feature in the relative absence of amnestic symptoms, frontotemporal dementia (FTD) should be considered more likely.
Cognitive histories should be comprehensive, and must include evaluation of memory, language, visuospatial function, executive functioning, and attention (Table 67-1). The comprehensive history should probe for autonomic symptoms and sleep patterns, with emphasis on symptoms associated with disorders of rapid eye movement (REM) sleep behavior and sleep apneas.
Table 67-1 Assessment of Major Cognitive Domains in Neurodegenerative Disorders |Favorite Table|Download (.pdf)
Table 67-1 Assessment of Major Cognitive Domains in Neurodegenerative Disorders
Memory: repetitive statements, misplacing items, missed appointment or medications, recalling recent/remote events
Language: speech fluency, comprehension, reading, writing, articulation, word-finding, content of speech, output, spelling
Visuospatial: getting lost, driving, object perception, completing household repairs, parking
Executive: planning, flexibility/rigidity in thinking, organization, multistep tasks
Motor: gait, falls, tremor, dysphagia, weakness, handwriting, coordination
Autonomic: light-headedness, bowel/bladder function, impotence, hypotension
The assessment of behavioral symptoms can be particularly helpful and sometimes critical in non-Alzheimer's neurodegenerative disorders. FTD is the most common cause of dementia in patients younger than the age of 60 years. Behavioral symptoms or personality change are commonly the presenting symptoms of this disorder (see Table 67-4 and discussion later in this chapter). When evaluating for change in ...