title: Patterns of brain activity during a semantic task differentiate normal aging from early Alzheimer's disease.
abstract: In a study of the effects of normal and pathological aging on semantic-related brain activity, 29 patients with Alzheimer's disease (AD) and 19 controls subjects (10 young and 9 older controls) performed a version of the Pyramids and Palm Trees Test that had been adapted for use during functional magnetic resonance imaging (fMRI). Young and older controls activated the left inferior and middle frontal gyri, precuneus and superior parietal lobule. Right frontal and left temporal cortices were activated only in the young. The AD group activated only the left prefrontal and cingulate cortex. Separate analyses of high- and low-performing AD subgroups showed a similar pattern of activation in the left frontal lobe, although activiation was more widespread in low performers. High performers significantly deactivated anterior midline frontal structures, however, while low performers did not. When the older adult and AD groups were combined, there was a significant positive correlation between left frontal and parietal activation and Mini-Mental State Examination (MMSE) score (covarying for age), suggesting a disease effect. A significant negative correlation between activation in the left temporal cortex and age (covarying for MMSE score) reflected a possible age effect. These differential effects suggest that semantic activation paradigms might aid diagnosis in those cases for whom conventional assessments lack the necessary sensitivity to detect subtle changes.
authors.affiliation: Clinical Neuroscience Centre, University of Hull, UK.
authors.forename: William Jonathan
authors.initials: WJ
authors.lastname: McGeown
authors.forename: Michael Fraser
authors.initials: MF
authors.lastname: Shanks
authors.forename: Katrina Elaine
authors.initials: KE
authors.lastname: Forbes-McKay
authors.forename: Annalena
authors.initials: A
authors.lastname: Venneri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000544:Alzheimer Disease / Q000473:pathology* / Q000503:physiopathology; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D012044:Regression Analysis; D012660:Semantics; D055815:Young Adult
chemical_list: D010100:Oxygen