Dementia Prevention: Methodological Explanations for Inconsistent Results. Nicola Coley, Sandrine Andrieu, Virginie Gardette, Sophie Gillette-Guyonnet, Caroline Sanz, Bruno Vellas, and Alain Grand. (2008). Epidemiol Rev 30 (1): 35-66.
Abstract: “The prevention of neurodegenerative dementias, such as Alzheimer disease, is a growing public health concern, because of a lack of effective curative treatment options and a rising global prevalence. Various potential risk or preventive factors have been suggested by epidemiologic research, including modifiable lifestyle factors, such as social contacts, leisure activities, physical exercise, and diet, as well as some preventive pharmacologic strategies, such as hormone replacement therapy, nonsteroidal antiinflammatory drugs, and Ginkgo biloba. […] The aim of this paper is to review the epidemiologic data linking potential protective factors to dementia or cognitive decline and to discuss the methodological limitations that could explain conflicting results. A thorough review of the literature suggests that, even if there are consistent findings from large observational studies regarding preventive or risk factors for dementia, few randomized controlled trials have been designed specifically to prove the protective effects of interventions based on such factors on dementia incidence. Because of the multifactorial origin of dementia, it appears that multidomain interventions could be a suitable candidate for preventive interventions, but designing such trials remains very challenging for researchers.”
Below are excerpts from the section “Social contacts, leisure activities, and physical exercise.” (Dance integrates all of these aspects: social engagement, leisure and cognitive activity, and physical exercise).
Prospective longitudinal studies
“Social contacts and social engagement. Fourteen studies have found an inverse relation between the level of late-life social contacts or engagement and the risk of dementia/Alzheimer disease (76–82) or cognitive decline (83–89). Midlife social engagement was assessed by one of these studies (82) but was not found to be related to dementia risk.
Two studies (90, 91) found only certain measures of social engagement to be associated with better cognitive function, and four studies found no association between participation in social activities (92, 93) or social network or support measures (91, 94) and cognition.
“Cognitive activities in late life. Twelve studies have demonstrated a relation between increased participation in cognitive activities in late life and a decreased risk of dementia (76–78, 95), Alzheimer disease (95–98), vascular dementia (95), or cognitive decline or impairment (87, 92, 93, 97,99, 100). No studies were identified that failed to find an association between cognitive activities and outcomes, although the positive effects in one of the above-mentioned studies (87) were seen only in some specific cognitive domains.
“Physical exercise. An increased frequency or intensity of physical exercise or activities in late life was associated with a decreased risk of dementia/Alzheimer disease (76, 77, 95, 101–107) or cognitive decline/impairment in 19 studies (87, 104, 108–115). However, nine studies found no association with dementia/Alzheimer disease (78, 96,97, 116, 117) or cognitive decline/impairment (92, 118–120). Two studies examined the effects of midlife physical exercise on the risk of dementia in late life and found conflicting results (121, 122).”