
Am J Psychiatry 163:1603-1610, September 2006
doi: 10.1176/appi.ajp.163.9.1603
© 2006 American Psychiatric Association
Increased Brain Activation During Working Memory in Cognitively Intact Adults With the APOE 4 Allele
Heather A. Wishart, Ph.D.,
Andrew J. Saykin, Psy.D.,
Laura A. Rabin, Ph.D.,
Robert B. Santulli, M.D.,
Laura A. Flashman, Ph.D.,
Stephen J. Guerin, M.D.,
Alexander C. Mamourian, M.D.,
Dorothy R. Belloni, B.S.,
C. Harker Rhodes, M.D., and
Thomas W. McAllister, M.D.
OBJECTIVE: Altered patterns of brain activity during cognitive tasks have been demonstrated using functional magnetic resonance imaging (fMRI) in mild cognitive impairment and Alzheimers disease. However, there have been few studies of adults at genetic risk for Alzheimers disease prior to the onset of symptoms. The purpose of this study was to determine whether brain activation patterns associated with working memory differ as a function of apolipoprotein E (APOE) genotype in cognitively intact adults. METHOD: Participants were cognitively intact, healthy adults who completed genotyping, comprehensive neuropsychological testing, and structural and functional neuroimaging. Twenty-two participants had the APOE 3/ 3 genotype, and 13 participants had the APOE 3/ 4 genotype. The study employed an auditory verbal N-back task to probe working memory-related brain activity. RESULTS: The 3/ 3 and 3/ 4 groups did not differ in demographic characteristics, cognitive ability, mood, or in-scanner task performance. The 3/ 4 group showed greater activity during working memory in the medial frontal and parietal regions bilaterally and in the right dorsolateral prefrontal cortex. There were no regions in which the 3/ 3 group showed greater activation than the 3/ 4 group. CONCLUSIONS: These results indicate that differences in brain activity are evident in cognitively intact individuals who are at risk for late-onset Alzheimers disease by virtue of their APOE allele status. As neuroprotective interventions become available, early detection will increase in importance. The combination of genetic and functional neuroimaging strategies may prove useful for monitoring individuals at risk for Alzheimers disease before the onset of cognitive symptoms.
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H. A. Wishart, A. J. Saykin, T. W. McAllister, L. A. Rabin, B. C. McDonald, L. A. Flashman, R. M. Roth, A. C. Mamourian, G. J. Tsongalis, and C. H. Rhodes
Regional brain atrophy in cognitively intact adults with a single APOE {varepsilon}4 allele.
Neurology,
October 10, 2006;
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