Visual function and cognitive speed of processing mediate age-related decline in memory span and fluid intelligence.
OBJECTIVE
To evaluate the relationship between sensory and cognitive decline, particularly with respect to speed of processing, memory span, and fluid intelligence. In addition, the common cause, sensory degradation and speed of processing hypotheses were compared.


METHODS
Structural equation modeling was used to investigate the complex relationships among age-related decrements in these areas.


RESULTS
Cross-sectional data analyses included 842 older adult participants (M = 73 years). After accounting for age-related declines in vision and processing speed, the direct associations between age and memory span and between age and fluid intelligence were nonsignificant. Older age was associated with visual decline, which was associated with slower speed of processing, which in turn was associated with greater cognitive deficits.


CONCLUSIONS
The findings support both the sensory degradation and speed of processing accounts of age-related, cognitive decline. Furthermore, the findings highlight positive aspects of normal cognitive aging in that older age may not be associated with a loss of fluid intelligence if visual sensory functioning and processing speed can be maintained.
Department of Psychology, University of Alabama at Birmingham, 415 Campbell Hall, 1300 University Boulevard, Birmingham, Alabama 35294-1170, USA. oclay@uab.edu
Olivio J
OJ
Clay
Jerri D
JD
Edwards
Lesley A
LA
Ross
Ozioma
O
Okonkwo
Virginia G
VG
Wadley
David L
DL
Roth
Karlene K
KK
Ball
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications*; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D008568:Memory; D008569:Memory Disorders / Q000150:complications*; D010829:Physiological Phenomena; D012677:Sensation; D013997:Time Factors; D014481:United States; D014786:Vision Disorders / Q000150:complications*; D014792:Visual Acuity