Cognition and Memory in Late Adulthood

Learning Objectives

By the end of this section, you will be able:

• Describe the concept of successful aging
• List behaviors and lifestyle choices that promote successful physical and cognitive aging
• Explain how normative aging and dementia relate to successful cognitive aging

Roberto never intended to keep working after he turned sixty years old, but at age sixty-two years, he’s still a successful plumber with no signs of slowing down. He’s delegated most of the harder physical work to his younger colleagues but still does physical labor two days a week and runs the business from his office the other three days. He enjoys the challenges of responding to emergencies and investigating the sources of problems, as well as all the social interaction that goes with the job. Roberto has learned to balance his work and professional lives to prevent burnout, and he deliberately carves out time for family activities and participation in his mosque Roberto and his family and coworkers agree that while he’ll have to stop working eventually, there’s no need for him to think about doing so right now.

What does it mean to age successfully? Traditionally, researchers studying this question considered cognitive and physical health, social or productive activities, and level of functioning (Rowe & Kahn, 1997). They later included goals such as avoiding disability and adding longevity, and subjective factors like enjoying life (Vaillant & Mukamal, 2001). Research has consistently identified four aspects of successful aging (Daniel, 2020; Rowe & Kahn, 1997; Kim & Park, 2017; Urtamo et al., 2019). They are health, physical ability, cognitive functioning, and psychological adaptation/social engagement. You’ll learn about the first three in this section, and psychological adaptation/social engagement in Chapter 16 Social and Emotional Development in Late Adulthood (Age 60 and Beyond).

Research on Successful Physical Aging and Health

There is potentially good news when it comes to physical functioning and health in later life (Figure 15.22). For example, the concept of compression of morbidity suggests that a healthy lifestyle can extend life expectancy while decreasing time spent in poor health and/or a highly dependent state (Fries, 1983). In other words, having a healthy lifestyle may help us not only live longer but also be healthier while doing so. In fact, improving health has better outcomes for the individual than simply prolonging life (Friedman, 2020; Jivraj et al., 2020), and it also lowers health-care costs (Hajat & Stein, 2018; Scott et al., 2021).

Figure 15.22 A healthy lifestyle can include not just good diet and exercise but also participation in enjoyable activities and social interactions. (credit: “Dancing Lady” by “kennie143”/nappy, Public Domain)

It Depends

Compression of Morbidity

James Fries (1983) first introduced the idea of compression of morbidity, a result that occurs when the average age of onset of chronic disease and disability increases at a faster rate than increases in life expectancy. In other words, people live a longer life while also experiencing fewer years in states of poor health and dependence. Such a trend could drastically reduce the costs associated with caring for a rapidly growing population of older adults while also improving their quality of life, allowing them to maintain their independence for longer than ever. Compression of morbidity was introduced as a theoretical concept, however. What do the data suggest?

It turns out that it depends. Research related to compression of morbidity yields mixed results. Crimmins and Beltrán-Sánchez (2010) conducted a review of research on some of the serious diseases common in late life and concluded that the data did not support compression of morbidity. Specifically, the age at which many health problems occurred stayed stable despite increasing life expectancy, and the amount of time people experienced disease and functional losses lengthened. The researchers’ conclusion was that people are living longer with health and functional limitations rather than delaying the onset of these problems.

Still, Fries and colleagues (2011) point to multiple longitudinal studies, some focused on healthy aging interventions or very healthy samples, that do support the idea of decreasing disability in older age. On a societal level, however, many major disease processes appear not to follow the trend. Perhaps more large-scale efforts to minimize risk factors for older adults through active, healthy lifestyles could result in the compression of morbidity on a societal level.

What factors might promote good health and physical ability in older people? It is well established that eating a diet high in fruits and vegetables, maintaining a healthy weight, ensuring proper hydration, and engaging in moderate or vigorous levels of exercise are all predictive of better physical health in later life (Buettner & Skemp, 2016; Evans & Cyr-Campbell, 1997; Herbert et al., 2022; Kreouzi et al., 2022; Poulain & Herm, 2022; Sowa et al., 2016). Sleep that is good in quality and sufficient in duration has also been found to be predictive of better health in these years (McCrae et al., 2008; Sivertsen et al., 2021).

Longitudinal research suggests that health-related tendencies and characteristics in middle adulthood, such as high blood pressure, are also predictive of later health outcomes (Perrig-Chiello et al., 2009). Even childhood experiences have been correlated with health in later life. Older individuals who had experienced traumatic events in childhood, such as abuse or exposure to substance abuse, later had higher incidences of heart disease, cancer, and many other chronic health conditions. This positive correlation is likely due to a combination of socioeconomic factors and riskier health behaviors throughout the lifespan (Merrick et al., 2019).

Another component of successful aging (Kim & Park, 2017) is maintaining physical functioning. Physical activity has been associated with many positive outcomes, such as better health, less stress, and better cognitive functioning. Current levels of physical activity may also predict future physical activity. Longitudinal research suggests that the combination of physical ability, activity, and nutrition in the earlier part of late adulthood is predictive of physical abilities and mobility (ability to walk) ten years later (Idland et al., 2012; Reis, 2020). Overall, research consistently suggests that the best thing you can do to increase the odds of aging successfully is to eat a healthy diet and exercise regularly. An unhealthy diet and sedentary lifestyle may even accelerate age-related declines in health and physical functioning.

Intersections and Contexts

Physical Fitness in Late Adulthood

Many people associate aging with decreased physical activity. Is it therefore safe to assume that an older adult is likely to have a lot of limitations regarding what they can achieve physically?

No. Many older adults exercise regularly and are in great physical shape. They may not be as capable as they were in their twenties, but they can maintain or even improve physical fitness well into later life. Largely, however, their success depends on how active they were in early and middle adulthood. It’s easier to maintain fitness than create it.

Physical activity can initially be uncomfortable and painful, but as the body gets used to activity, the pain and discomfort decrease. Older adults who aren’t used to being active may thus need extra encouragement to keep up with it, especially since normative aging often brings joint pain and loss of flexibility and stamina.

While ordinary exercise and physical activity appear sufficient to keep most people healthy, some strive to achieve impressive physical accomplishments during their later years. The Appalachian Trail is a backpacking hike that stretches nearly 2,200 miles, starting in Georgia and ending in Maine. People who attempt the entire trail in one year, which requires hiking consistently for about six months and averaging 14 to 20 miles a day, are considered “through-hikers.” Only one in four through-hikers successfully complete this challenging trek (Appalachian Trail Conservancy, 2022). An eighty-three-year-old going by the trail name of Nimblewill Nomad recently broke the record of oldest successful through-hiker, set just four years earlier by a hiker calling himself Grey Beard (then eighty-two years old).

Research on Brain Health

How do we keep our brain healthy as we age? While behavioral and lifestyle characteristics have not been linked to early-onset Alzheimer’s disease or Lewy body dementia, a recent comprehensive review of research estimated that around 40 percent of dementia cases were associated with risk factors like high blood pressure and obesity that can be minimized or controlled with a healthy diet and regular exercise (Alzheimer’s Association, 2024; Livingston et al., 2020).

Different characteristics across the lifespan are both predictive of dementia and changeable. Research by Livingston and colleagues (2020) identifies which potentially modifiable risk factors are associated with different life stages, as well as the percentage reduction in dementia prevalence if that risk factor is eliminated (Table 15.3). For example, not smoking in late life reduces your risk of developing dementia by 5 percent. According to this research, about 40 percent of risk factors associated with developing dementia are potentially controllable, suggesting that throughout our lifespan, we can reduce our likelihood of experiencing it.

Life Stage	Risk Factor	Percentage Reduction
Early life	Less education	7%
Midlife	Hearing loss	8%
	Traumatic brain injury	3%
	Hypertension	2%
	Alcohol consumption	1%
	Obesity	1%
Later life	Smoking	5%
	Depression	4%
	Social isolation	4%
	Physical inactivity	2%
	Air pollution	2%
	Diabetes	1%

These risk factors aren’t exhaustive. Other potentially modifiable risk factors for dementia are sleep problems, vitamin deficiencies, and poor oral health (Alzheimer’s Association, 2024; Crane et al., 2013; Livingston et al., 2020; Nianogo et al., 2022; Zhang et al., 2021). Many of these can affect aspects of health other than cognitive functioning, so addressing any of them may benefit us in multiple ways. In some cases, we don’t even need a formal diagnosis to have increased dementia risk; for example, some research has demonstrated that even in people who do not have diabetes, higher blood glucose levels are associated with higher dementia risk (Crane et al., 2013). Thus, controlling factors such as diet and activity levels, and keeping blood glucose levels in a healthy range, may lower dementia risk even if we don’t develop diabetes.

Another positive step, and one that might surprise you, is protecting your hearing throughout adulthood. Hearing loss may contribute to stress, social isolation, and lack of environmental stimulation, all of which are already linked to dementia (Huang et al., 2023; Zhang et al., 2021). Hearing loss has also been associated with cognitive decline and an increase in dementia risk (Livingston et al., 2020; Nianogo et al., 2022; Zhang et al., 2021). The reason for this connection is unknown, but hearing loss may be indicative of underlying problems with brain functioning and therefore a symptom of dementia rather than a cause.

Regardless of the cause, treating hearing loss, usually with hearing aids, can lower a person’s risk of dementia (Livingston et al., 2020; Nianogo et al., 2022; Zhang et al., 2021). Someone showing memory problems and confusion should have their hearing tested before assuming dementia may exist; they may simply not hear what others are saying.

Given the same number of dementia-related changes to the brain, some individuals may exhibit greater resistance to damage than others. These people have more cognitive reserve, characteristics that are protective against dementia by delaying onset and reducing symptoms. People with higher educational and occupational attainment earlier in life tend to have greater cognitive reserve, experiencing slower decline if they develop dementia, and with less severe symptoms. One potential explanation is that higher levels of education are predictive of higher verbal ability, which decreases the risk of dementia (Boyle et al., 2021; Nianogo et al., 2022; Tucker & Stern, 2011; Zhang et al., 2021). However, this also means that people who get less education, particularly those who don’t complete high school, are at increased risk of dementia. This is particularly important for people of low socioeconomic status and marginalized groups such as people of color, who may lack opportunities to receive education (Nianogo et al., 2022).

High levels of aerobic exercise and cognitively stimulating activities have been found to increase cognitive reserve (Cheng, 2016; Nianogo et al., 2022; Zhang et al., 2021), as have engagement in creative activities and an active social life in later ages (Hansdottir et al., 2022; Zhang et al., 2021) (Figure 15.23). These may not only decrease the risk of experiencing dementia, they could also minimize the severity of any dementia a person has.

Figure 15.23 An active social life is one of the factors that can help increase cognitive reserve in later life. (credit: “U.S. Army Corps of Engineers Sacramento District retiree luncheon at Club Pheasant in West Sacramento on May 16, 2017” by U.S. Army Corps of Engineers Sacramento District/Wikimedia Commons, Public Domain)

Research on Successful Cognitive Aging

Many of the behaviors that help prevent dementia are also related to minimizing normative cognitive declines as well as enhancing overall health. For example, aerobic exercise is especially beneficial for slowing cognitive aging and maintaining cognitive ability (Gomez-Pinilla & Hillman, 2013; Nianogo et al., 2022; Zhang et al., 2021). Education, social engagement, giving up or avoiding smoking, and managing weight and blood glucose levels are also linked with successful cognitive aging (Alzheimer’s Association, 2024; Nianogo et al., 2022; Zhang et al., 2021). These actions may benefit us in several ways. For example, participating in hobbies may reduce stress, provide cognitive stimulation, and increase and strengthen our social network, any one of which can be considered protective (Choi, 2019; Zhang et al., 2021).

Some research has suggested that following diets that are plant based and/or low in fat, sugar, and sodium may be beneficial (Zhang et al., 2023). One example is the Dietary Approaches to Stop Hypertension (DASH) diet (NHLBI, 2006), which emphasizes eating foods high in calcium, fiber, magnesium, potassium, and protein and low in salt and saturated fat. Although the DASH diet was initially developed to help people lower their blood pressure and cholesterol, some evidence exists that it may be helpful for promoting healthy cognitive function (Zhang et al., 2021) (Figure 15.24).

Figure 15.24 The DASH diet emphasizes fruits, vegetables, and protein from lean meats and beans, and encourages limiting consumption of foods high in fat, sugar, and salt. (credit: modification of work “DASH Eating Plan” by NHLBL/National Heart Lung, and Blood Institute, Public Domain)

Cognitive changes are minimal and specific to certain aspects of our cognition for most adults age sixty and beyond. In fact, research suggests that while cognitive changes are common, they are not universal or inevitable. For example, while fluid abilities tend to peak near the beginning of early adulthood before starting a steady decline, this trajectory may be somewhat avoidable. Some research supports the “use it or lose it” idea, which says fluid abilities start declining because we stop practicing them (just when we’re completing our formal education, perhaps), while we tend to maintain or improve other cognitive skills we frequently use (Hultsch et al., 1999; van Balkom et al., 2020).

Consistent with this idea, older adults tend to rely more on crystallized abilities when solving problems, while younger adults lean toward fluid abilities (Artistico et al., 2019; Chen et al., 2017). If, however, we look for opportunities to use our fluid abilities, we may be able to prevent or at least slow the decline. For example, think back to the opening story in 15.3 Cognition and Memory in Late Adulthood, about Ahmad who began volunteering but had no crystallized skills or knowledge to rely on; instead, this activity required the use of fluid abilities to learn and apply new information.

Is it possible to use training programs to improve cognitive functioning, as physical exercise programs improve physical functioning? In general, it might be. In a research context, cognitive training programs typically ask participants to complete structured tasks such as recalling short lists of words, distinguishing between similar-sounding words, following a sequence of instructions, and identifying the pattern in a series of numbers (Ball et al., 2002; Mahncke et al., 2006). Sometimes the tasks are similar to everyday activities, such as reading a map or remembering items on a shopping list (Ball et al., 2002). More recently, researchers have explored using video games as cognitive training exercises (Belchior et al., 2019; Clemenson et al., 2020; Xu et al., 2020).

Results show that cognitive training programs, and games that require coordinating multiple skills, can be effective in improving older adults’ performance on abilities that typically decline in later years, such as inductive reasoning, episodic memory, and even processing speed, and participants maintained these benefits over time (Ball et al. 2002; Belchior et al., 2019; Bherer et al., 2021; Bonnechère et al., 2021; Clemenson et al., 2020; Hausman et al., 2023; Mahncke et al., 2006; Rebok et al., 2014; Xu et al., 2020). However, while cognitive training and “brain games” websites have been shown to improve processing speed and cognitive performance in older adults, stimulation through social interaction and participation in enjoyable activities is likely to be more realistically attainable and equally, if not more, beneficial (Küster et al., 2016).