| |
Abstract:
Alzheimer's disease (AD) is the most common cause of dementia
in older adults. Neuropsychological studies have delineated the
cognitive deficit and neuropathologic studies have characterized
the histologic hallmarks of this disease. However, few studies have
examined the functional competency of brain regions and the
relationship to the behavioral deficits in AD. Functional MRI
(fMRI) allows non-invasive investigation of the relationship
between behavior and brain activation. Six AD patients and 7
healthy age-matched controls were studied with fMRI at 3 Tesla
during intentional encoding of scenes. Subjects viewed the stimuli
in blocks of novel scenes, repeated scenes, or fixation. Post-scan
memory testing revealed poor memory for the scenes in the AD group.
AD patients had less medial temporal lobe (MTL) response to novel
stimuli compared to fixation than did healthy controls.
Novelty-associated MTL activation in AD patients was even more
affected. In contrast, AD patients had preserved activations within
earlier processing areas (primary visual cortex and fusifom gyrus)
during both initial and repeated presentations of the stimuli.
Functional MRI may be provide insights into the mechanisms of the
cognitive deficits in AD and other dementing illnesses and may also
provide a useful diagnostic and prognostic tool.
|
