Normative data for tasks of executive function and working memory for Australian-born women aged 56 – 67

Abstract

Normative data for tests of working memory and executive function (a term adopted to cover a range of cognitive skills) are primarily based on the U.S. population and are not always specific for gender or education levels. The diagnosis of, and research into, cognitive diseases rely on the use of relevant normative data. This study presents normative data for an ageing, female, Australian-born population, and an analysis of the factors that contribute to variation in performance. Three tasks of executive function: Trail Making Test, Part B (Trails-B); Tower of London, and the oral version of the Symbol Digit Modalities Test (SDMT), and a working memory task (Letter-Number Sequencing, LNS) were administered as part of a 14-item neuropsychological battery to 257 participants (M age = 60 years, range = 56 – 67 years), who have been participating in the Melbourne Women's Midlife Health Project. The Center for Epidemiological Studies Depression Scale (CES-D) was also administered. A regression analysis incorporating age, years of education, CES-D score, current use of hormone therapy and menopausal status as independent variables demonstrated that education and age contributed to the variation in SDMT and the LNS but not in the Tower of London. Education alone contributed to variation in Trails-B, although there was a trend for performance to decrease with age. Mood, hormone therapy use, and menopausal status were unrelated to test scores. Tables of mean scores were constructed for age ranges and level of education, for each of the tests except the Tower of London, which was presented as education groups only. Partial correlations between test performances demonstrated significant correlations between all the major components of the tests. This study provides education- and age-based normative data for tests of executive function for the ageing female, Australian-born population.

Acknowledgements

Funding was provided in part by Alzheimer's Association grant IIRG-01-2684. The authors wish to thank Gael Trytell for her able assistance in testing participants, and all the women who participated in this project.