Type of Document Dissertation Author Kitner-Triolo, Melissa Hughes Author's Email Address Melissa@lpc.grc.nia.nih.gov URN etd-05122000-16440006 Title Predicting Future Age-Related Cognitive Delcine: Processing Speed and Frontal Lobe Functioning Degree PhD Department Psychology Advisory Committee
Advisor Name Title Crawford, Helen J. Committee Chair Bell, Martha Ann Committee Member Blieszner, Rosemary Committee Member Franchina, Joseph J. Committee Member Prestrude, Albert M. Committee Member Zonderman, Alan B. Committee Member Keywords
- Working Memory
- Cross-sectional aging
- Reaction Time
- Longitudinal aging
- Prefrontal cortex
Date of Defense 2000-05-03 Availability unrestricted AbstractPREDICTING FUTURE AGE-RELATED COGNITIVE DECLINE: PROCESSING SPEED AND FRONTAL LOBE FUNCTIONING
Melissa H. Kitner-Triolo
Helen J. Crawford, Ph.D., Chair
The present study assessed the impact of aging on cognitive functioning over six to 16 years in exceptionally healthy individuals (20 to 79 years) drawn from the Baltimore Longitudinal Study of Aging. The first study (N = 380 women, 757 men) examined the relationship between age and speed of processing as measured by five reaction time (RT) tasks (simple reaction time to complex reaction time involving varying amounts of inhibitory and working memory processing). Unlike previous research, this study additionally assessed the impact of processing speed, working memory, inhibitory processing, and interference RT measures in predicting future performance 6-16 years later (N=103) on (1) mental status (Blessed Information-Memory-Concentration, Mini-Mental State Examination), and prefrontal mediated neuropsychological tests (Trail Making A and B; verbal and category fluency; WAIS digits forward and backwards, California Verbal Learning Test proactive interference index). Regression analyses assessed which theoretical approach, speed of processing (Salthouse, 1996) or prefrontal cortex (Hasher & Zacks, 1988; West, 1996), better explained cognitive change.
Age-related cognitive slowing was observed for initial RT tasks. Especially among the oldest studied (62-79 years of age), slower speed of processing was accelerated by task complexity. Increases in response time were substantially steeper for older as opposed to younger participants. Men were faster than women were on simple RT and a RT task that involved inhibitory processing. A 6-9 year age decline in speed of processing only occurred among individuals over 60 years. RT omission and commission errors showed similar results.
Hierarchical regression analyses determined that RT tasks involving inhibitory control, working memory and interference were most predictive of future prefrontal-mediated cognitive performance (Trail Making B, digit span backwards, letter and
category fluency). Prediction of the prefrontal outcome measures of Trail Making A and digit span forward performance from simple reaction time was mediated by the RT measures (inhibitory control, working memory and interference), but not the other way around. Thus, the data most strongly support the Inhibitory Deficit (Hasher & Zacks, 1988) and Prefrontal Cortex Function (West, 1996) theories. There was little support for the processing speed theory (Salthouse, 1996).
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Melissahkt.pdf 364.14 Kb 00:01:41 00:00:52 00:00:45 00:00:22 00:00:01
If you have questions or technical problems, please Contact DLA.