To understand successful brain aging, it is helpful to look first at what we mean by “optimal†aging. Unlike what we associate with losses that accumulate over time (“normal†or “usual†aging), optimal aging improves the individual’s functioning. Now think about people you would nominate as successful, or optimal, agers. What characterizes them? Are they physically stronger than their age peers? Do see better or hear better than people in their 20s and 30s? How about some of those older adults who have become cultural icons, such as Betty White or Jack LaLanne? In an earlier blog, I wrote about these and other amazing older adults, who I call the “Age Busters,†because they “bust†the stereotypes that aging inevitably involves infirmity and obsolescence. You probably know plenty of age busters in your family, neighborhood, or community; maybe you’re one yourself!
These examples show that it is possible for both ordinary and famous older adults to defy traditional stereotypes about aging. How do these optimal agers pull it off? Clearly, there is some set of qualities that allow them to maintain their zest and vitality well into their 60s, 70s, and beyond. To answer this question, we turn to what gerontologists Rowe and Kahn (1998), defined as “successful aging:†(1) absence of disease, (2) absence of disability, (3) high cognitive and physical functioning, (4) and engagement with life.  However, based on numerous investigations, including the University of Michigan’s Institute of Social Research Health and Retirement Study (HRS) on approximately 10,000 U.S. adults (McLaughlin et al., 2010), Rowe and Kahn’s definition is overly restrictive. Using all 4 criteria limits the estimate of successful agers to about 10%. The problem was in the restrictiveness of having “no disease.†Approximately 80% of the HRS elders rated themselves as disability-free, but only about 40% stated that they had no health problems. The Rowe and Kahn definition also fails to take into account social class, race and ethnicity, as shown by studies on other samples (e.g. urban African American older adults in a study by Cernin et al., 2011). In the HRS, successful agers were more heavily represented among Whites and among those with a college education or higher.
The World Health Organization (WHO) definition takes a more liberal approach, and recognizes that people who are objectively not free from health conditions can still have a high quality of life. The WHO defines “active ageing†as the process of optimizing opportunities for health, participation and security in order to enhance quality of life as people age. WHO makes explicit the role of autonomy and independence, placing greater emphasis on the individual’s ability to get around in the environment, rather than on whether or not the individual needs physical accommodations due to disability.
Seeking to quantify successful aging further, and with these considerations in mind, University of California at San Diego researchers led by Ipsit Vahia (2012) administered several standardized measures to nearly 1,950 women participating in the San Diego site of the Women’s Health Initiative (WHI) Study in an attempt to predict self-rated successful aging. They found that the women highest in subjectively-rated successful aging had high scores in what they called the psychological protective factors of resilience, self-efficacy, and optimism, they had positive emotional functioning (low depression and emotional symptoms), and were low in self-rated disability.
Being emotionally resilient can give you an edge in aging successfully. However, cognitive abilities are also key to the overall ability to become an Age Buster. Being able to use your brain may not guarantee you emotional happiness or even material success, but having greater brain reserves can help you adapt to the challenges of daily life. Older adults regard their cognitive abilities as central to their sense of identity, which is one reason that they so greatly fear developing Alzheimer’s disease.
Researchers are now setting on the path to discover the elements of what they call “successful cognitive aging,†or cognitive performance that is above the average for an individual’s age group as objectively measured (Fiocco Yaffe, 2010).  Instead of seeking only to define and diagnose neurocognitive disorders, the pioneering researchers in this field are following up on the concept of “plasticity,†identified by neuroanatomists Coleman and Flood (1987) after their discoveries that in the normal brain, neurons continue to develop the ability to form new branches even as the total numbers of neurons may diminish with age.
Successful cognitive aging clearly requires successful brain aging. To prove this point, Northwestern University’s Theresa Harrison and colleagues (2012) identified a subset of participants in one of their studies who met the criteria for memory “SuperAgers†in that they performed at levels comparable to those of middle-aged adults. When Harrison and her team looked at the brain scans of the SuperAgers, they found that they were equivalent in terms of cortical thickness in key areas to those of the middle-aged participants, and better than those of the age-matched non-SuperAger peers. If you want to be a memory Age Buster, it looks like you have to be a brain Age Buster as well.
Over the past 25 years or so, neuroscientists have been quietly amassing a set of studies in which the brain scans of older adults are compared to those of younger adults, cataloging the relationships of brain scans to cognitive performance. Although the Harrison et al. study is notable in showing a direct correspondence between cortical thickness and memory performance, others have brought some pretty good correlational evidence to bear on the question. UC San Diego researcher Jeste teamed up with a group led by Lisa Eyler in 2011 to review 80 of the best of these studies to find out whether people with better brain response (not just size) would also have better cognitive performance. In other words, does successful brain aging translate into successful cognitive aging?
Of the 80 studies, 39% showed a clear connection among the older adults between brain activation and cognitive performance and another 32% showed mixed findings. The remainder showed either no relationship or a negative relationship. Breaking the findings down by brain region, the best findings appeared for the frontal cortex, tapped by so-called “executive†functions important for planning and decision-making, and thought to be targeted particularly negatively by aging. Another area called the medial temporal lobe, which contains the all-important-for-memory structure known as the hippocampus, tended to show positive relationships to performance, but not consistently. Eyler and her team, from this evidence, concluded that “a simple model of bigger structure  –greater brain response –better cognitive performance might not be accurate for this region†(p. 118).
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