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Left Parietal Lobe Disruption May Signal Alzheimer's Risk

Women at high risk for Alzheimer's disease show increased brain activation in the left parietal region during a fluency task.

This finding adds weight to the possibility there is disruption of functional circuits involving the left parietal lobe in asymptomatic people at increased risk for Alzheimer's disease (AD). Disparities in resting metabolism and in functional activation between cognitively normal people at high and low risk for AD have been shown in imaging studies.

Authors of a recent study postulated the increased parietal activation they found in high-risk subjects during a paired associates recall task might overlap activation typically observed in verbal fluency.

Thus, C. D. Smith and colleagues from the University of Kentucky College of Medicine, Lexington, Kentucky, United States, examined whether parietal activation is altered in a letter fluency task in people with no symptoms but at increased risk for AD.

These researchers compared cortical activation between two groups of cognitively normal women differing in their risk for developing AD using fMRI. A letter fluency task was used, which activates left frontal and parietal regions.

Although the risk groups differed in family history of AD and APOE allele status, they were matched on age, which averaged 53 years, as well as on education and measures of cognitive performance.

Regional patterns of brain activation were found to be similar between groups and similar to patterns observed by other investigators. However, the high-risk group showed significantly increased activation in the left parietal region despite identical letter fluency performance between risk groups.
Neurology 2002;58:1197-1202. "Women at risk for AD show increased parietal activation during a fluency task"

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