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Pages 1-16

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From page 1...
... Furthermore, emerging evidence that the incidence and prevalence of dementia are declining in high-income countries offers hope that public health interventions can be effective in preventing cognitive decline and dementia. Although the evidence base on how to prevent or delay these conditions has been limited at best -- despite the many claims of success made in popular media and advertising -- a growing body of prevention research is emerging.
From page 2...
... Furthermore, the committee's task was to offer recommendations as to what can appropriately be communicated to members of the public, who generally are interested in staying cognitively healthy as they age and are unlikely to make the distinctions that are used in research. When describing the overall goal addressed by this study, instead of specifying particular conditions or listing all relevant conditions repeatedly, the committee uses the shorthand umbrella term preventing cognitive decline and dementia.
From page 3...
... In most cases, the committee relies on longitudinal population-based cohort studies when evaluating observational data; any use of case control studies is specifically noted.
From page 4...
... Accordingly, NIA asked the National Academies to convene an expert committee to help inform the design of a new AHRQ systematic review, whose results then would be used by the committee as the primary evidence base for recommendations on the appropriate content for communicating with the public about steps that can be taken to prevent, delay, or slow the onset of mild cognitive impairment (MCI) and clinical Alzheimer's-type dementia (CATD)
From page 5...
... COMMUNICATING WITH THE PUBLIC ABOUT INTERVENTIONS TO PREVENT COGNITIVE DECLINE AND DEMENTIA The AHRQ systematic review identified no specific interventions that are supported by sufficient evidence to justify mounting an assertive public health campaign to encourage people to adopt them for the purpose of preventing cognitive decline and dementia. The systematic review did, however, find some degree of support for the benefit of three classes of intervention:
From page 6...
... The suggestion that blood pressure management and increased physical activity be included among the interventions with some degree of support is not based primarily on RCT evidence from the AHRQ systematic review; rather, in the committee's judgment, there is sufficient complementary evidence from observational studies and neurobiological understanding to include them in communications with the public. This evidence supports blood pressure management for people with hypertension for preventing, delaying, or slowing CATD based on dementia incidence data, and increased physical activity for delaying or slowing ARCD based on cognitive test performance data.
From page 7...
... and can translate to maintaining independence in instrumental activities of daily living, such as remembering to take medications and driving. The AHRQ systematic review found that the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE)
From page 8...
... The suite of cognitive training interventions in the ACTIVE trial -- which included cognitive training and social engagement in a group setting -- differ substantially from commercial computer-based "brain training" applications, the effects of which appear to be short term 2  Tables summarizing effect sizes for the impacts of the ACTIVE trial cognitive training intervention on cognitive testing outcomes and instrumental activities of daily living (among other outcomes) at the 2-, 5-, and 10-year time points can be found in the 2017 AHRQ systematic review, Interventions to prevent age-related cognitive decline, mild cognitive impairment, and clinical Alzheimer's-type dementia (see Appendix A)
From page 9...
... The AHRQ systematic review found that RCT data do not offer strong support for the use of blood pressure management in patients with hypertension to delay or slow ARCD or to prevent, delay, or slow MCI and CATD. Only one trial (Syst-Eur)
From page 10...
... It is, of course, also possible that the inconsistent results are indicative of a lack of true effect on cognitive decline and dementia incidence. As a supplement to the encouraging pattern of RCT results described in the AHRQ systematic review, the effects of increased physical activity on delaying or slowing ARCD are consistent with a causal relationship when prospective cohort studies and knowledge of neurobiological processes are considered, although reverse causality cannot be ruled out.
From page 11...
... The absence of high-strength evidence supporting long-term beneficial cognitive effects for the interventions included in the AHRQ systematic review results in part from methodological limitations of past intervention studies. These include small sample sizes, short follow-up periods, relatively homogeneous study populations that may not have included the highestrisk groups, and use of suboptimal and heterogeneous outcome measures and assessment tools.
From page 12...
... However, the multiplicity of tests used in the field to measure cognitive performance has hampered such assessments, and consistent cognitive outcome measures need to be developed to enable pooling of data in meta-analyses. Recommendation 2: Methodological Improvements When funding research on preventing cognitive decline and demen tia, the National Institutes of Health and other interested orga nizations should improve the methodologies used in this field by supporting studies that to the extent possible • identify individuals who are at higher risk of cognitive decline  and dementia and tailor interventions accordingly • increase participation of underrepresented populations to study  intervention effectiveness in these populations • begin more interventions at younger ages and have longer  follow-up periods • use consistent cognitive outcome measures across trials to  enable pooling • integrate robust cognitive outcome measures into trials with  other primary purposes • include biomarkers as intermediate outcomes  • conduct large trials designed to test the effectiveness of an  intervention in broad, routine clinical practices or community settings PRIORITIES FOR FUTURE RESEARCH The absence of definitive data demonstrating the effectiveness of any of the interventions evaluated in the AHRQ systematic review underscores the need for future research on preventing cognitive decline and dementia.
From page 13...
... Recommendation 3: Highest Priorities for Research The National Institutes of Health and other interested organiza tions should support further research to strengthen the evidence base on the following categories of interventions, alone or in com bination, which are supported by encouraging but inconclusive evidence: • cognitive training • blood pressure management • increased physical activity Other Priorities for Future Research The AHRQ systematic review covered a large number of interventions for which the current evidence base from RCTs is insufficient to draw any conclusions regarding their impact on cognitive decline and dementia. As noted earlier, given this lack of RCT evidence, the committee considered data from observational prospective cohort and risk factor studies, as well as biological plausibility, in identifying other priorities for future research.
From page 14...
... An added challenge is that many of the interventions that show promise today, such as better control of hypertension and diabetes and regular physical activity, have widely accepted health benefits and are broadly prescribed. Similarly, while smoking has been shown to be a risk factor for dementia, it is difficult to imagine an ethically acceptable long-term RCT that would include an untreated control group and could meet the stringent quality criteria of the EPC.
From page 15...
... The fact that the report does not strongly support a public health campaign focused on actively promoting adoption of any type of intervention should not be taken to reflect a lack of progress or prospects for preventing, delaying, or slowing the discussed conditions. Although inconclusive, clinical trials and other studies have yielded encouraging data for some interventions, and the public should have access to this information to inform choices on how to invest time and resources to maintain brain health with aging.


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