title: Losses in gross brain volume and cerebral blood flow account for age-related differences in speed but not in fluid intelligence.
abstract: Age-related gross head size; adjusted age-related change in brain volume and carotid and basilar blood flow; as well as scores on 3 tests of fluid intelligence (gf), 2 tests of information-processing speed, 2 memory tests, and 3 tests of executive function were obtained from 69 volunteers aged from 62 to 84 years. Brain volume negatively predicted scores on all 10 cognitive tasks, accounting for up to 78% of age-related variance in scores on the speed tasks and on 1 executive task. Cerebral blood flow (CBF) negatively predicted scores on 8 cognitive tasks, accounting for up to 36% of age-related variance in speed scores. However, neither brain volume nor CBF accounted for significant age-related variance between individuals on any of 3 gf tests. We conclude that speed, but not gf, is an exceptionally sensitive behavioral index of the progress of gross brain changes that affect cognition in old age and that speed and gf do not reflect integrity of the same functional systems.
authors.affiliation: Age and Cognitive Performance Research Centre, University of Manchester.
authors.forename: Patrick
authors.initials: P
authors.lastname: Rabbitt
authors.affiliation: Department of Radiology, University of Manchester.
authors.forename: Marietta
authors.initials: M
authors.lastname: Scott
authors.affiliation: Department of Radiology, University of Manchester.
authors.forename: Neil
authors.initials: N
authors.lastname: Thacker
authors.affiliation: Department of Psychology, University of Manchester.
authors.forename: Christine
authors.initials: C
authors.lastname: Lowe
authors.affiliation: Department of Radiology, University of Manchester.
authors.forename: Alan
authors.identifier: 0000-0002-1623-0383
authors.initials: A
authors.lastname: Jackson
authors.affiliation: Department of Geriatric Medicine, Hope Hospital, University of Manchester.
authors.forename: Mike
authors.initials: M
authors.lastname: Horan
authors.affiliation: Department of Geriatric Medicine, Hope Hospital, University of Manchester.
authors.forename: Neil
authors.identifier: 0000-0003-0794-2386
authors.initials: N
authors.lastname: Pendleton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000254:growth & development*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D007206:Individuality; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012727:Sex Characteristics