An approach that includes healthy diet, physical activity, adequate sleep, and mentally and socially stimulating activities is more important for preserving cognitive health with age than any individual intervention.
Physical Activity
Staying physically active throughout life is critical to maintaining healthy cognitive function. Exercise has been linked to slower rates of age-related brain atrophy in key areas of the brain involved in cognitive decline, and being physically active in midlife is associated with slower cognitive decline and reduced risk of cognitive impairment and dementia later in life.
Preclinical research suggests exercise can stimulate production of growth factors such as brain-derived neurotrophic factor (BDNF), which promote neuroplasticity. Exercise also improves cerebrovascular function, supports formation of new blood vessels in the brain, and increases blood flow.
A large body of evidence indicates that any type and amount of physical activity is better than none when it comes to cognitive health. It is clear that both aerobic exercise and strength training can prevent or delay cognitive decline in older adults, regardless of their current cognitive status. Even seated exercises have cognitive benefits for older patients who are unable to exercise upright.
Mental Activity
Engaging in activities that are mentally stimulating has been shown in numerous studies to be important for cognitive health during all life stages. It is thought that education and other forms of mental stimulation build cognitive reserve (ie, the brain’s ability to use alternative neuronal pathways to accomplish cognitive tasks) over a lifetime. Having greater cognitive reserve may delay the onset of symptoms related to aging or pathological changes in the brain.
Higher education level and bilingualism over a lifetime have protective effects on cognitive function, and early research suggests educational pursuits and language acquisition at older ages may still benefit some aspects of cognition. A meta-analysis of studies found that musical practice is associated with preservation of a variety of aspects of cognitive function, including those affected by aging. The effect is strongest in those with long-term musical training, but is also observed after short-term musical training later in life.
Mentally stimulating leisure activities have been linked to cognitive benefits in multiple studies. For example, in one study in 100 cognitively healthy older adults, long-term jigsaw puzzlers were found to have higher function in all aspects of cognitive ability examined. There is some evidence that doing Sudoku and crossword puzzles can benefit the aging brain. A study in 16,572 participants aged 65–100 years found that higher frequency of engagement in word or number games was associated with better cognitive performance on tests of memory, numeracy, and verbal fluency both at baseline and after two years. Even those who began playing word or number games after the beginning of the study demonstrated better cognitive function at the end than those who did not play word or number games regularly. The effect was equally strong in participants of all ages, and was more pronounced in those with a lower level of education. Another study found that activities such as computer use, crossword puzzles, handicrafts, and educational courses were each associated with reduced cognitive decline over one year. Early research suggests mentally stimulating computerized programs may be useful for improving cognitive performance in patients with mild cognitive impairment and dementia.
Stress Reduction
Chronic stress, anxiety, depression, and sleep disturbance are often inter-related. These conditions have well-established detrimental effects on brain structure and function, and are associated with increased risk of dementia. Stress reduction techniques, such as meditation and yoga, may have a role in slowing age-related cognitive decline and preventing cognitive impairment. Mindfulness meditation, for example, has consistently been found to positively affect brain structure, function, and plasticity, including in regions of the brain associated with cognitive dysfunction.6 Long-term yoga practitioners have been found to be less likely to have age-related brain atrophy and perform better on some cognitive tests compared with those not practicing yoga. Other research found similar effects in long-term meditators. Looking at cognitive function in subjects with a wide age range, one study determined that long-term yoga practitioners and meditators had slower cognitive decline and more resilient neuronal networks than those with neither practice.
Preliminary studies have indicated that meditation practice can improve memory, attention, and executive function in older adults, and may mitigate age-related cognitive decline.164 Mindful movement therapies such as tai chi, yoga, and walking meditation also have positive effects on quality of life, mood, and cognitive function. In one randomized controlled clinical trial in 118 participants with an average age of 62, an eight-week Hatha yoga program involving postures, breathing, and meditation exercises improved performance on tests of attention and information processing speed.
Social Engagement
Social engagement, like physical and mental activity, may be an important mediator of healthy brain function throughout life. A growing number of studies indicate high social engagement and strong social networks are correlated with reduced age-related cognitive decline, mild cognitive impairment, and dementia. On the other hand, progressive loss of cognitive function, as well as physical function, can lead to diminished strength of social networks and increased isolation, contributing to further cognitive losses.
Strong social networks have been correlated with better cognitive function in older adults and reduced likelihood of experiencing anxiety and depression symptoms in those with mild cognitive impairment. One study found that cognitive decline in older men and women over an eight-year period was mitigated by regular engagement in social activities, regardless of cognitive status at the beginning of the study. Similarly, social engagement was correlated with slower cognitive decline in 543 cognitively healthy 67-year-old participants who were monitored for eight years. Volunteering was identified in one study as a particular predictor of cognitive resiliency with aging, which may be due in part to the combined social and cognitive aspects of many volunteer activities.
Participating in group social activities may become more important to cognitive health at older ages.176 Even in the very old, social engagement appears to be beneficial; participation in art, craft, and social activities were all noted as protective against mild cognitive impairment in a group of 256 people aged 85 years and older who were cognitively normal at the beginning of the study and were monitored for approximately four years.
Sleep
Sleep is a critical time for brain rest and repair, and both acute and chronic sleep disturbances have measurable negative impacts on physical, emotional, and cognitive health. Long-term sleep deprivation and chronic sleep restriction or fragmentation damages neuronal function and contributes to stress, mood symptoms, and cognitive dysfunction. In healthy older adults, subjective cognitive symptoms are reported more often in those also reporting sleep disturbances.
Aging is naturally associated with diminished sleep quantity and quality, which may influence cognitive function by disrupting circadian regulation and stress hormone signaling, and promoting systemic inflammation, metabolic disturbance, and fat deposition. Furthermore, poor sleep may influence cognition through epigenetic changes affecting neuroplasticity.
According to large meta-analyses of research into this relationship, the optimum amount of sleep for healthy cognitive function appears to be 7–8 hours per night, with both shorter and longer sleep durations associated with increasing risks of cognitive decline, mild cognitive impairment, and dementia.
Sufficient daily activity and a nighttime environment that promotes sleep may help older people struggling with sleep disorders. Strategies that have demonstrated some effectiveness include:
- Daytime activities. Because too little or too much activity during the day can contribute to sleep problems at night, maintaining a balanced schedule of daily activities and engagements may help prevent daytime napping and facilitate better nighttime sleep.
- Meditation. Mind-body therapies and meditations promote relaxation and may increase time asleep.
- Cognitive behavioral therapy. Cognitive behavioral interventions for insomnia focus on reframing negative thought patterns around sleep.
- Sleep-enhancing devices. Use of devices that improve the sleep environment (eg, earplugs, eye masks, white noise machines, weighted blankets, and devices that play sleep-inducing music) have all demonstrated some effectiveness in reducing sleep disturbance.
- Daytime bright-light therapy. Bright light therapy may help increase daytime activity, reduce daytime napping, and reset the circadian clock, thereby assisting in restoring normal sleep patterns.
Obstructive Sleep Apnea and Cognitive Dysfunction
Obstructive sleep apnea is a common form of sleep-disordered breathing characterized by periodic episodes of complete or partial airway closure, resulting in apnea (lack of breathing) or hypopnea (insufficient breathing), during sleep. Falling blood levels of oxygen and rising levels of carbon dioxide as a result of apnea and hypopnea cause brain arousal that triggers the resumption of sufficient breathing. Frequent cycling between apnea and arousal causes sleep fragmentation that, when chronic, can lead to disrupted circadian signaling, dysregulation of the stress response, systemic inflammation, and increased oxidative stress. Obstructive sleep apnea can be a major contributing factor in metabolic and cardiovascular diseases, as well as cognitive dysfunction.
The relationship between obstructive sleep apnea and cognitive decline, mild cognitive impairment, and dementia has been observed in numerous studies. According to a large meta-analysis that included 14 studies with over 4 million participants, sleep-disordered breathing is associated with a 26% increased likelihood of developing cognitive impairment. A growing body of evidence suggests treatment of sleep apnea with continuous positive airway pressure (CPAP) can reduce sleep apnea-related cognitive decline.
Diet
An eating pattern based on the traditional Mediterranean diet has been shown to have anti-aging effects on brain, cardiovascular, and metabolic functions, and on overall longevity. Findings from a variety of studies suggest eating a Mediterranean-style diet can slow cognitive decline and may reduce risk of dementia.
Mediterranean diet. With its emphasis on fruits, vegetables, unrefined whole grains, legumes, and extra virgin olive oil, as well as moderate amounts of seafood, fermented dairy products, and red wine with meals, the traditional Mediterranean diet provides ample amounts of critical nutrients such as mono- and polyunsaturated fatty acids, antioxidants, vitamins, minerals, and phytonutrients. It can be used as a template that can be adapted to favor local and seasonal availability of specific foods.
A study including 832 participants examined every two to three years for up to 18 years found that those whose diets most closely reflected a Mediterranean diet experienced significantly less cognitive decline than those whose diets least reflected a Mediterranean diet. A study based on data collected over 16 years from 27,842 men participating in the Health Professionals’ Follow-up Study found that those whose diets were most Mediterranean-like were 36% less likely to report poor subjective cognitive function than those whose diets were least Mediterranean-like. Examining the brains of cognitively normal older-age subjects has revealed that adherence to a Mediterranean-like dietary pattern is associated with reduced β-amyloid accumulation. The components of the diet most closely linked to this effect were high fruit and vegetable consumption and moderate wine consumption.
- Extra virgin olive oil. While it appears that the combination of eating habits comprising the Mediterranean diet is the key to its efficacy, the high consumption of extra virgin olive oil featured in the diet is thought to be an important reason for its protective effect on cognition. Several preclinical studies indicate polyphenols in extra virgin olive oil can reduce β-amyloid and tau accumulation and toxicity, and may modulate microRNA profiles. One clinical trial in 285 older adults compared three diets: Mediterranean diet supplemented with as much as 1 liter per week (more than ¼ cup per day) of extra virgin olive oil; Mediterranean diet including 30 grams per day of mixed nuts; and a low-fat diet. After 6.5 years, the olive-oil-supplemented group had better cognitive performance than the other two groups.
Coffee
Numerous preclinical and clinical studies have examined the potential for drinking coffee to help prevent cognitive decline. Caffeine and coffee are recognized to improve short-term memory and cognition, and some research indicates long-term coffee consumption could protect against dementia and cognitive decline. Furthermore, preclinical models have demonstrated plausible biological mechanisms for bioactive components in coffee to be neuroprotective. For instance, in a three-year study in 145 cognitively healthy elderly participants, moderate-to-heavy coffee drinking was linked to reduced cognitive decline, as well as better preservation of brain white matter and cerebral blood flow. Similarly, an analysis of 11 prospective studies found that the highest levels of coffee consumption were associated with a 27% lower risk of Alzheimer disease. However, some studies have found that smaller amounts also appear to protect cognitive function. An analysis of nine prospective studies concluded that optimal protection resulted from 1‒2 cups of coffee per day, while other studies suggest coffee’s effects on cognition and the brain are complex and require further study.
Caloric Restriction
Caloric restriction, a dietary intervention in which calorie intake is reduced but adequate nutrient intake is preserved, has been shown to delay the onset of age-related diseases and extend lifespan in many organisms. This effect is thought to be due to a triggering of resilience mechanisms that enhance cellular resistance to stress. This effect is known as hormesis.
In rodent models, caloric restriction was associated with decreased neural stem cell senescence, increased neuroplasticity, and better cognitive performance. Specifically, caloric restriction has been found in animal models to stimulate neural stem cell activity, promote normal metabolism of phospholipids needed for myelin production, lower stress reactivity and stress-related changes in brain structure, and induce epigenetic changes that support youthful gene expression in aging brains. Some of the same metabolic and molecular changes and health benefits associated with caloric restriction in animals have been demonstrated in humans engaging in 25% caloric restriction or through an intermittent fasting strategy, combined with physical activity.
Celiac Disease, Gluten Sensitivity, and Cognitive Decline
Celiac disease is a chronic condition caused by an autoimmune response to gluten, a protein found primarily in wheat. Patients with celiac disease typically have a high degree of systemic and gastrointestinal inflammation, as well as a marked imbalance of gut microorganisms (dysbiosis). It is estimated that 10% of celiac disease patients also experience neurological symptoms related to the condition, such as headaches, lack of muscle coordination, numbness or tingling of extremities, depression, and cognitive impairment ranging from mild reversible cognitive symptoms (such as “brain fog”) to permanent neurological damage and dementia.
Non-celiac gluten sensitivity is a gastrointestinal disorder caused by an inflammatory reaction to gluten that does not appear to involve autoantibodies. It can lead to similar consequences as celiac disease, including gut and systemic inflammation and dysbiosis, potentially leading to neuroinflammation and cognitive symptoms.
In older individuals, neurological manifestations of celiac disease and non-celiac gluten sensitivity are frequently attributed to age-related cognitive decline or misdiagnosed as cognitive impairment or even Alzheimer dementia, yet with accurate diagnosis and implementation of a gluten-free diet, these symptoms often resolve.