SIDEBAR 3.3Neurodegenerative Disorders

Alzheimer’s disease is the most common form of dementia among elderly people, affecting an estimated 4.5 million Americans. It is a brain disorder that seriously affects a person’s ability to carry out daily activities (NIA 2006). Its hallmark characteristics are the presence of excessive amyloid plaques (i.e., abnormal clumps) and neurofibrillary tangles (tangled bundles of fibers) that damage parts of the brain involved in thought, memory, and language (see Figure 3.5).

Brain diagram

Brain diagram. SOURCE:, adapted from Palmer (1999).

Huntington’s disease is an inherited disease—that is, a mutation, or genetic change, in the Huntington’s disease gene is passed on from a parent to a child. This change causes degeneration of brain cells that result in uncontrolled movement, loss of intellectual faculties, and emotional disturbances, such as mood swings and depression (NINDS 2006a).

Pick’s disease is also known as fronto-temporal dementia. It is a syndrome associated with shrinking of the frontal and temporal anterior lobes of the brain (see diagram) that disrupts either an individual’s ability to understand language (difficulty speaking or understanding speech) or causes changes in the person’s behavior (e.g., loss of impulse control resulting in inappropriate social behavior, lack of empathy, apathy) (NINDS 2006b).

From: 3, Nuclear Medicine Imaging in Diagnosis and Treatment

Cover of Advancing Nuclear Medicine Through Innovation
Advancing Nuclear Medicine Through Innovation.
National Research Council (US) and Institute of Medicine (US) Committee on State of the Science of Nuclear Medicine.
Washington (DC): National Academies Press (US); 2007.
Copyright © 2007, National Academy of Sciences.

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