Cognitive Aging Progress in Understanding and Opportunities for Action (2015) / Chapter Skim
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4A Risk and Protective Factors and Interventions: Lifestyle and Physical Environment
4A Risk and Protective Factors and Interventions: Lifestyle and Physical Environment
Pages 109-148
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From page 109... ...
Risk and protective factors include all of the personal lifestyle, behavioral, social, medical, and genetic characteristics of an individual or environment that are associated with, respectively, decreases or increases in cognitive function. There is wide variability in cognitive functioning levels among individuals, and risk and protective factors may affect a person's long-term cognitive trajectory in varying ways.
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From page 110... ...
(Chapter 4C) • Physical activity and • Medications • Cognitive stimulation and exercise • Cerebrovascular and training • Education and cardiovascular disease • Arts intellectual engagement and risk factors • Pharmacologics, • Social isolation, • Delirium and nootropics, and loneliness, and social hospitalization supplements engagement • Major surgery and • Trans-cranial direct current • Diet general anesthesia stimulation • Vitamins • Thyroid disorders • Multi-domain trials • Alcohol • Chronic kidney disease • Smoking • Cancer • Substance abuse • Depression • Physical environment -- • Traumatic brain injury air pollution and • Hearing and visual loss occupational exposures • Sleep • Stress • Genetic factors NOTES: A number of other topics are relevant to this discussion, including early childhood factors: developmental conditions, childhood exposures; environmental exposures, including to trace metals or pesticides; elder abuse and neglect; psychological factors, including resilience, anxiety, mental illness, posttraumatic stress disorder; atrial fibrillation; chronic liver disease; chronic lung disease; diseases affecting the brain (infections, inflammatory conditions, neoplasm, and neurodegenerative diseases)
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From page 111... ...
Although some individuals with acute decline may return to their baseline level of cognitive functioning, others may make only a limited recovery, and still others may find that their cognitive function does not improve at all; the long-term impacts of acute cognitive decline on cognitive aging are not fully understood. Furthermore, much of the literature on medical-related risk factors has focused on neurodegenerative diseases and less research on these factors has been devoted to cognitive aging per se.
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From page 112... ...
The following factors affect the interpretation of the evidence about the risk factors for cognitive aging and the ability to draw conclusions from that evidence: • Age range: Ideally, an evaluation of risk factors for cognitive aging would include representative populations of adults followed from young adulthood to very late life. Many studies include only cross sectional (one-time)
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From page 113... ...
Interpreting Intervention Studies Intervention studies have the potential to provide strong evidence for behavior change or other interventions that could mitigate the risk factors associated with cognitive aging. The synergistic effects of various components of an intervention (e.g., the social component of a physical activity intervention)
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From page 114... ...
PHYSICAL ACTIVITY AND EXERCISE Physical activity is strongly linked to healthy aging and remaining independent, and it has been associated with helping individuals maintain their physical and cognitive function throughout life and also with older adults developing fewer chronic conditions (Lee at el., 2012; NIH, 2014b)
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From page 115... ...
. In a recent systematic review, 21 of 24 prospective studies found an association between physical activity and cognitive outcomes, and all four of the cross-sectional reports included did so as well (Beydoun et al., 2014b)
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From page 116... ...
Evidence from Intervention Studies A substantial number of intervention studies have reported that physical activity and exercise have a benefit on cognition. For example, in one early randomized trial, three groups 4A-1 older adults (an aerobic exercise Figure of group, a strength and flexibility group, and a non-exercising control group)
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From page 117... ...
People older than 65 years showed more benefits than those from 55 to 65 years of age, and exercise sessions longer than 30 minutes showed larger cognitive benefits than shorter ones. More recently, behavioral assessments of physical activity and exercise effects have been augmented with human neuroimaging studies, particularly studies using functional magnetic resonance imaging (fMRI)
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From page 118... ...
. Although the evidence is strong that physical activity and exercise can positively affect cognitive aging, many unanswered questions need to be addressed in future research, such as: • Do different modes of exercise produce different cognitive benefits?
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From page 119... ...
. Supporting the concept of cognitive reserve, cross-sectional studies of nondemented and demented individuals have reported greater levels of brain atrophy among individuals with higher cognitive reserve than among those with lower cognitive reserve and similar levels of cognitive functioning, suggesting that the effects of atrophy on cognition are reduced in individuals with higher reserve (Arenaza-Urquijo et al., 2013; Liu et al., 2012; Querbes et al., 2009; Reed et al., 2010; Sole-Padulles et al., 2009)
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From page 120... ...
As educational levels become more uniform in advanced societies, indicators of the quality of education, especially literacy, may become better predictors of cognitive function. The available evidence emphasizes the importance of both early life education and maintaining cognitive function over the life span for peak cognitive capacities.
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From page 121... ...
increased cognitive demand due to chronic surveillance for and protection from threats; (5) increased depression and decreased physical activity; (6)
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From page 122... ...
. Fifth, there may be gender differences in associations between social engagement and cognitive aging.
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From page 123... ...
, evidence from RCTs is needed before recommendations can be made for specific social interaction interventions. Social engagement is often integral to other activities, such as physical activity or participation in the arts, that also have shown cognitive benefits (see Chapter 4C)
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From page 124... ...
, but it concluded that the quality of the available evidence was low at that time. In two more recent studies, Cache County and Health ABC, global cognitive function scores were found to be significantly higher among those who most adhered to the Mediterranean diet than among those who followed it the least (p = 0.001)
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From page 125... ...
Long-term RCTs that attempt to change people's dietary patterns are difficult and expensive, yet many scientists have called for these in order to more firmly determine whether the Mediterranean diet can actually slow cognitive aging. The intake of n-3 fatty acids is one aspect of the Mediterranean diet that has received a great deal of attention.
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From page 126... ...
Summary Based on observational studies and limited clinical trials, dietary interventions such as the DASH and Mediterranean diets appear to have promise but their efficacy and effectiveness need to be confirmed in additional clinical trials and community-based studies. While interesting and promising in some studies, the evidence regarding their effects on cognitive aging is too inconclusive to warrant recommendations for dietary change.
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From page 127... ...
systematic review, 9 of 21 prospective studies and 2 of 6 cross-sectional studies did find positive associations between antioxidant intakes, especially vitamin E, and cognitive outcomes (Beydoun et al., 2014a)
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From page 128... ...
In the NIA systematic review, 12 of 19 prospective studies and 11 of 14 prospective studies found higher homocysteine levels to be associated with poor cognitive outcomes (Beydoun et al., 2014a)
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From page 129... ...
Furthermore, high levels of alcohol intake may be associated with psychiatric comorbidity, which also may have adverse cognitive consequences. Compared to either abstinence or excessive alcohol consumption, moderate drinking in adulthood -- generally
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From page 130... ...
. In the NIA systematic review, 8 of 18 prospective studies found the J- or U-shaped association between moderate alcohol consumption and cognitive outcomes, as did 9 of 12 cross-sectional studies (Beydoun et al., 2014a)
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From page 131... ...
, while these risks were not significantly increased among former smokers. In the NIA systematic review, 16 of 29 prospective studies observed associations between smoking and poorer cognitive outcomes, while four studies found associations with some outcomes or in some subgroups, and nine studies found no associations or associations in which smokers had better cognitive outcomes than non-smokers (Beydoun et al., 2014a)
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From page 132... ...
, but, as above, several problems arise in interpreting this research, including the presence of psychiatric comorbidity and neurotoxic exposures. A systematic review of the impact of methadone, an opioid congener used in the treatment of opiate addiction, suggested that impaired cognitive function was correlated with its use (Wang et al., 2013)
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From page 133... ...
. Air pollutants may have other important, if indirect, effects on cognitive function through their contributions to the development of cardiopulmonary conditions, including ischemic heart disease, stroke, lung conditions (Gold and Mittleman, 2013; Shah et al., 2013)
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From page 134... ...
While knowledge about the effects of occupational exposures on cognitive performance is an extremely important area for prevention, research on these effects is always challenging: many similar chemical and other exposures occur simultaneously; industrial processes and consequent exposures change with advances in production; exposed workers may be subject to other factors, occupational or non-occupational, that could lead to cognitive decrements; some studies use clinical dementia or specific neurodegenerative diseases as outcomes rather than cognitive aging; and workers in jobs with substantial occupational chemical exposures may have lower levels of education, itself an important risk factor for cognitive change in later life. Despite the uncertainties, one clear message is that whenever workers may be exposed to a substance for which there is reasonable evidence of neurotoxicity, effective exposure prevention programs should be enforced in the workplace at all times to protect both younger and older workers.
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From page 135... ...
. Thus, it is not surprising that the evidence relating stress to cognitive outcomes has been compiled in diverse ways and has produced results that are inconsistent and difficult to interpret.
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From page 136... ...
. In the Longitudinal Aging Study Amsterdam, the death of a child or grandchild was associated with faster cognitive decline, and having experienced fewer major life events was associated with better cognitive function (Comijs et al., 2011)
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From page 137... ...
2008. Physical activity and enhanced fitness to improve cognitive function in older people without known cognitive impairment.
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From page 138... ...
2012. Social activity and cognitive functioning over time: A coordinated analysis of four longitudinal studies.
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From page 139... ...
2013. Dietary antioxidants, cognitive function and dementia -- A systematic review.
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From page 140... ...
2009. The role of occupational complex ity in trajectories of cognitive aging before and after retirement.
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2013. Substance use and mental health characteristics associated with cognitive functioning among adults who use methamphetamine.
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From page 142... ...
2013. Mediterranean diet, cognitive function, and dementia: A system atic review.
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From page 143... ...
2010. Physical activity over the life course and its association with cognitive performance and impairment in old age.
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From page 144... ...
2013. Mediterranean diet and cognitive function in older age: Results from the Women's Health Study.
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From page 145... ...
2013. Social isolation and loneliness: Relationships with cognitive function during 4 years of follow-up in the English Longi tudinal Study of Ageing.
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From page 146... ...
2013. Mediterranean diet habits in older individuals: Associations with cognitive functioning and brain volumes.
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From page 147... ...
2013. Methadone maintenance treatment and cognitive function: A systematic review.
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