In recognition of the Baltimore Longitudinal Study of Aging’s (BLSA’s) 50th anniversary, the NIA’s 6th Annual Nathan W. Shock Symposium was extended to highlight findings from the past 5 decades and to look to the future of the study. On September 11–12, some 250 scientists, clinicians, administrators, and guests gathered in Baltimore to hear presentations and discuss the contributions of longitudinal research to the understanding of healthy aging and age-related pathology, with a particular focus on the landmark BLSA.
“It is an honor and a pleasure to be part of this historic study,” said Dr. Luigi Ferrucci, who has directed the BLSA since 2002. “We have a team of committed, creative, and hard-working scientists, nurses, health workers, and administrators who share the legacy of the study and are proud to contribute to its continuation. And most important are the many, many volunteers who have participated over the years, giving their time and sharing their lives with us so that together, we may learn what may improve the quality of life for older people.”
The BLSA began in 1958 as the brainchild of Dr. Nathan W. Shock, head of the NIH’s Gerontology Branch and the first scientific director of NIA. Dr. Shock co-founded the effort with Arthur H. Norris, the initial study coordinator who implemented Dr. Shock's research designs, and Dr. William W. Peter, a retired U.S. Public Health Service physician and the study’s first volunteer, who recruited many of his colleagues to the study. The BLSA’s main objective was to answer the question: “What is normal aging?”
The way BLSA investigators collected data to answer this question is what made the study groundbreaking. First, Dr. Shock and his colleagues designed the BLSA to study healthy, community-dwelling adults. Until then, most research on aging involved institutionalized older adults with many health problems, which made it difficult to differentiate normal aging from changes caused by diseases.
Second, the study was unique because the volunteers were observed over time, or longitudinally, while most other studies were cross-sectional, meaning one age group was compared to another to see how they were different. In cross-sectional studies it is impossible to determine whether differences between individuals of different ages are attributable to age or to different life experiences.
Researchers at the symposium noted that over the past 50 years the BLSA has contributed significantly to the body of knowledge about aging in a variety of areas, in which scientists have been able to measure natural, age-related declines and compare them with declines related to disease. They have also been able to build knowledge about the relationships between health risk factors and aging and to track trends for behaviors that promote health or risk for disease. Some major findings from the BLSA concern:
Cardiology—Investigators observed that age-related changes in the arteries, such as stiffening, increase the risk of cardiovascular disease and, reciprocally, that cardiovascular disease accelerates arterial aging.
Psychology—Several BLSA measurements indicate that personality traits change little after age 30 and that changes in personality with age typically result from disease.
Cognition—In 2008, BLSA scientists reported that almost everyone experiences a steady rate of natural decline in their cognitive abilities. However, the rate of decline is faster among people who developed Alzheimer’s disease at certain points in time.
Oncology—Researchers discovered a pattern of rise in prostate-specific antigen (PSA) levels about 5 years before a prostate cancer diagnosis. They also observed that measuring the rate of PSA change is more sensitive than using a fixed cutoff value to detect possible prostate cancer. Examining the ratio of free PSA to total PSA helps reduce incorrect diagnosis, and the percentage of free PSA in the blood can predict the aggressiveness of prostate cancer a decade before diagnosis.
Metabolism—Investigators found that men’s waist circumference increased with age while their hip circumference remained stable. In contrast, women showed approximately equal changes in waist and hip measurements. Thus, even though women typically carry more total body fat than men, men develop a more dangerous fat distribution pattern.
The BLSA’s golden anniversary was also recognized at the annual meeting of the Gerontological Society of America (GSA) in November 2008. Researchers led by Dr. Ferrucci reprised their review of findings for the GSA’s broader audience. The scientists were joined by participants from the scientific community and others who recounted their long-time association with the study, with a specific mention and appreciation of the study staff.
A great deal has been learned from the BLSA, but much more remains to be explored. For example, while BLSA scientists have been able to distinguish changes due to normal aging from those caused by health problems, relatively little is known about why certain individuals have excellent health well into their 80s while others experience disease and physical decline as they age.
In 2009, the BLSA will begin the Insight into the Determinants of Exceptional Aging and Longevity (IDEAL) study. IDEAL will examine the genetic, environmental, social, and behavioral factors linked to preserving health and function in the oldest old by studying people 80 years and older who are living free of physical and cognitive disease. Along with factors that contribute to extraordinary health at very advanced age, scientists hope to identify the risk factors that may be associated with the loss of exceptional aging over time.
Healthy Aging: Lessons from the Baltimore Longitudinal Study of Aging