Purpose: This study was conducted to examine age-related differences in cognitive function, and their relation to higher-level competence of elderly living in an urban community.
Method: Participants were 438 individuals (males 168, females 270) aged 70 to 84 years living in an urban community in Tokyo. Three cognitive performance tests, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Digit Symbol, Word Fluency Test, and the WAIS-R Digit Span, were employed for estimating cognitive function, and the TMIG Index of Competence for measuring higher-level competence. In the Index, three constructions: "Instrumental Self-Maintenance", "Intellectual Activity", and "Social Role" were involved.
Results and conclusions: Age-related differences in the cognitive tests were analyzed using ANCOVA controlling for educational year. Age-related differences between younger elderly (70-79 years old) and older elderly (80-84 years old) were observed with the WAIS-R Digit Symbol, Word Fluency Test and the WAIS-R Digit Span. The results indicate that information processing speed, executive function and primary memory in community-dwelling elderly continue to decline in old age, and this trend is salient in the old-old. We carried out partial correlation analysis and multiple regression analysis for exploring the relationships between cognitive function and the sub-scales in the TMIG Index of Competence, controlling for age and educational year. Cognitive function was significantly and positively related with the sub-scales in the Index, this being especially robust for "Intellectual Activity". The results suggest that higher-level competence can be modestly determined with reference to cognitive function, and "Intellectual Activity" may have a stronger relation with cognitive function than the other two sub-scales in the Index.