Episodic memory functioning in very old age : Individual differences and utilization of cognitive support

Sammanfattning: Wahlin, Å. Episodic memory functioning in very old age: Individual differences and utilization ofcognitive support. Doctoral Dissertation, Department of Clinical Neuroscience and Family Medicine,Division of Geriatric Medicine, Karolinska Institute; and Stockholm Gerontology Research Center,Section of Psychology. Correspondence: Stockholm Gerontology Research Center, Box 6401, S- 11382 Stockholm, Sweden. 1996; ISBN 91-628-1860-0The general aim of the present doctoral thesis was to examine potential age-related differences inepisodic memory performance and utilization of cognitive support in very old age. An additionalobjective was to investigate the influence of individual difference variables within demographic (e.g.,education, gender), psychometric (e.g., general cognitive status; MMSE, fluid intelligence), lifestyle(e .g ., social activity), and biological (e.g., serum vitamin B 12) domains on episodic memory functioningin late life. A population-based sample of normal adults between 75 and 96 years served as subjects.Across all five studies, participants were carefully screened for health, using a variety of exclusioncriteria (e.g., depression, dementia, sensory loss). In Study I, II, and III the aims were addressedemploying several episodic memory tasks, including verbal and non-verbal materials, and examiningutilization of cognitive support in the form of task-relevant prior knowledge, extended study time, copycues at retrieval (recognition), organizability of the to-be-remembered materials as well as categorycuing at retrieval. In these studies, the age-related deterioration of episodic memory performance wasfound to be slight, albeit reliable. Furthermore, the ability to utilize cognitive support appeared to remainunaffected by advancing age. Several individual difference variables including age, MMSE score, fluidintelligence, and level of formal education, were generally and positively related to memory performance.Study IV examined the impact of demographic and lifestyle factors on episodic memory andperformance benefits due to the provision of cognitive support. Results indicated that age wasnegatively related to performance, whereas education and participation in social activities exerted apositive influence. Exercise was also positively related to performance, but only in the least supportedtasks. With regard to performance benefits due to cognitive support, education was positively relatedto benefits from more study time and item organizability, age was negatively related to the effect of itemorganizability, and social activity was positively associated with the ability to benefit from retrievalcues. Study V explored the impact of low serum vitamin B12 and folic acid on episodic memoryperformance and utilization of cognitive support. It was found that participants with low levels of serumfolic acid performed significantly worse than controls in both free recall and recognition of verbalmaterials, and that this deterioration was most pronounced in participants with low levels of both folicacid and vitamin B 12. However, vitamin status did not affect utilization of more study time or copy cues(recognition). Overall, the five studies indicated that the well-known age-related deficit in episodicmemory performance continues into very old age, although the ability to utilize the studied forms ofcognitive support is less affected by advancing age. In addition to age, several individual-differencefactors contributed to the amount of explained variance in both episodic memory performance andutilization of cognitive support, such that advantaged older persons (e.g., in terms of education andsocial activity) remembered more and benefited more from cognitive support. The results also indicatethe relevance of including serum vitamin status as a health screening factor in research concerning age-related differences in episodic memory performance.Key words: Episodic memory, aging, cognitive support, individual differences. Åke Wahlin, 1996 Number of pages 60: ISBN 91-628-1860-0