Losses in gross brain volume and cerebral blood flow account for age-related differences in speed but not in fluid intelligence.
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.
Rabbitt
Patrick
P
Age and Cognitive Performance Research Centre, University of Manchester.
Scott
Marietta
M
Department of Radiology, University of Manchester.
Thacker
Neil
N
Department of Radiology, University of Manchester.
Lowe
Christine
C
Department of Psychology, University of Manchester.
Jackson
Alan
A
0000-0002-1623-0383
Department of Radiology, University of Manchester.
Horan
Mike
M
Department of Geriatric Medicine, Hope Hospital, University of Manchester.
Pendleton
Neil
N
0000-0003-0794-2386
Department of Geriatric Medicine, Hope Hospital, University of Manchester.
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