The Betula prospective cohort study: Memory, health and aging

The objective of this article is to present an overview of a prospective cohort study involving a total of 3,000 subjects whose ages were 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 years when first tested. The design of the study includes three waves of data collection. The first of these waves was conducted in 1988-1990, the second in 1993-1995, and the third will be conducted in 1998-2000. One sample of 1,000 subjects in these age cohorts underwent testing in 1988-1990 (100 subjects per cohort). This sample and two additional samples were tested in 1993-1995 and will be tested again in 1998-2000. Subjects take part in extensive health and memory examinations, and interviews about social factors. The memory testing covers a wide range of memory functions. The chief objectives of the study are to (a) examine the development of health and memory in adulthood and old age; (b) determine early preclinical signs of dementia; (c) determine risk factors for dementia; and (d) assess premorbid memory function in subjects who are in accidents or acquire diseases during the course of the study. Cross-sectional data from the first sample show a continuous age-related deterioration in tasks assessing episodic memory, no age-related deficit in semantic memory tasks when educational level is partialed out, and no age effects in priming. Finally, the relationships between subjective (i.e., self-rating) and objective (blood and urine parameters, blood pressure and pulse, medication, recent contacts with a physician, and sensory function) indexes of health, on the one hand, and memory performance, on the other, were in general relatively weak in all age groups. The health-memory relationship was completely mediated by age, whereas the age-memory relationship was only partially mediated by health.