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fMRI studies of associative encoding in young and elderly controls and mild Alzheimer's disease
R A Sperling1, J F Bates, E F Chua
1Memory Disorders Unit, Department of Neurology, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA. reisa@rics.bwh.harvard.edu
Objective:
To examine alterations in patterns of brain activation seen in normal aging and in mild Alzheimer's disease by functional magnetic resonance imaging (fMRI) during an associative encoding task.
Methods:
10 young controls, 10 elderly controls, and seven patients with mild Alzheimer's disease were studied using fMRI during a face-name association encoding task. The fMRI paradigm used a block design with three conditions: novel face-name pairs, repeated face-name pairs, and visual fixation.
Results:
The young and elderly controls differed primarily in the pattern of activation seen in prefrontal and parietal cortices: elderly controls showed significantly less activation in both superior and inferior prefrontal cortices but greater activation in parietal regions than younger controls during the encoding of novel face-name pairs. Compared with elderly controls, the Alzheimer patients showed significantly less activation in the hippocampal formation but greater activation in the medial parietal and posterior cingulate regions.
Conclusions:
The pattern of fMRI activation during the encoding of novel associations is differentially altered in the early stages of Alzheimer's disease compared with normal aging.