Study Design and Measures
A longitudinal study
The BLSA's innovative, longitudinal design helps investigators piece together a more accurate picture of normal aging. Before the BLSA, scientists generally conducted cross-sectional studies, comparing participants in one age group to a different set of people in another age group. Most of the differences between these groups may not have been attributed to age but the result of life experiences, genetics, or environmental factors. Imagine comparing two people, one who has lived through two wars and the other who was raised in a peaceful and prosperous society. How each aged might be different, but the effect of age alone would be difficult to sort out. By looking at the same individuals over time, external influences are reduced. Longitudinal research allows scientists to gather thousands of case studies of human aging.
An observational study
Unlike a clinical trial, no interventions are tested in the BLSA. The BLSA is an observational study. Researchers measure physical and cognitive changes associated with aging in real time among a dedicated group of BLSA participants who come in for testing at regular intervals over the course of their lives. Presently, participants under age 60 are assessed every 4 years; those aged 60 to 79 years come every 2 years, and participants aged 80 and older are assessed annually. During the assessment, they receive comprehensive health, cognitive, and functional evaluations that take nearly 3 days to complete. A consortium of scientists collects and analyzes data from this study population with the aim of characterizing normal and exceptional aging, along with age-associated health issues, such as frailty.
The BLSA measures:
- Changes that occur over the aging process
- Biological, behavioral, genetic, and environmental factors that account for these changes, helping researchers to understand why the effects of aging differ in different individuals
- Potential predictors and risk factors for specific diseases, frailty, and other end-points reflecting success or failure to adapt to aging
- Possible targets for interventions that may positively affect several aspects of the aging process and prevent age-related diseases
- Factors that predict healthy aging across the life span
View this short video, which features several walking tests conducted in the BLSA Gait Lab. The tests help researchers study the components of gait in older adults to gain a better understanding of how gait mechanics change with age and how these changes may impact overall mobility.