Preventing Vascular Effects on Brain Injury and Cognition Late in Life: Knowns and Unknowns

Abstract

For some researchers, the relationship between prevalent cardiovascular risk factors and late-life cognitive decline is not worthy of further study. It is already known that effective treatment of vascular risk factors lowers risk of such major outcomes as stroke and heart attack, the argument goes; thus, any new information about the relationship between vascular risk factors and another major outcome - late-life cognitive decline-- is unlikely to have an impact on clinical practice. The purpose of this review is to probe the logic of this argument by focusing on what is known, and what is not known, about the relationship between vascular risk factors and late-life cognitive decline. The unknowns are substantial: in particular, there is relatively little evidence that current vascular risk factor treatment protocols are adequate to prevent late-life cognitive decline or the clinically silent brain injury that precedes it. In addition, there is relatively little understanding of which factors lead to differential vulnerability or resilience to the effects of vascular risk factors on silent brain injury. Differential effects of different classes of treatments are similarly unclear. Finally, there is limited understanding of the impact of clinically-silent neurodegenerative disease processes on cerebrovascular processes. Further study of the relationships among vascular risk factors, brain injury, and late-life cognitive decline could have a major impact on development of new vascular therapies and on clinical management of vascular risk factors, and there are promising avenues for future research in this direction.

The Relation of Obesity to Performance in Verbal Abilities, Processing Speed, and Cognitive Flexibility in Old Age: The Role of Cognitive Reserve

“…First of all, confirming prior research [23,24,25], we found that obesity was related to a lower performance in verbal abilities, processing speed, and cognitive flexibility. This further corroborates the view that obesity is a major health-related antecedent of impairments in multiple domains of cognitive functioning such as memory, processing speed, and executive functioning in old age [20,21,22]. Furthermore, in line with prior evidence [6,14,15], we found that higher educational attainment, greater engagement in a broad variety of leisure activities, and higher cognitive level and lower physical demand of individuals' occupation were related to a better performance in all three investigated cognitive performance measures in old age.…”

“…In general, obesity [body mass index (BMI) ≥30 [17]] is a major health risk, particularly in older adults. For instance, obesity is related to cardiovascular diseases and metabolic disorders such as diabetes [18,19], which are risk factors for cognitive impairment in old age [20,21,22]. In line with this, obesity has been found to be associated with impaired cognitive functioning such as memory and executive functioning in old age [23,24,25].…”

“…The rationale underlying this view is that cognitive reserve may generally be a protective factor against disease-related cognitive changes in later adulthood. Specifically, cognitive stimulation may increase the brain's potential to effectively recruit neural networks and cognitive processes in situations in which the brain must react and adapt, for example in individuals at elevated risk for cognitive impairment in old age that is (at least partly) caused by obesity, cardiovascular diseases, and diabetes [18,19,20,21,22,23,24,25,26,27], thereby enhancing cognitive performance [3,4]. This view has been corroborated by evidence that cognitive reserve (operationalized as engaging in different social activities and head circumference) may have a preserving effect on cognitive functioning (such as a lower risk for dementia) even when controlling for BMI [28,29].…”

High-Density Lipoprotein Cholesterol Level Relates to Working Memory, Immediate and Delayed Cued Recall in Brazilian Older Adults: The Role of Cognitive Reserve

“…In contrast, a critically low HDL-C level (<40 mg/dL) is related to an altered lipid metabolism, elevated lipid levels (including high plasma levels of low-density lipoprotein cholesterol [LDL-C] that are a marker of the transport of cholesterol from the liver to the cells via LDL particles), and therefore an increased risk for cardiovascular and cerebrovascular diseases [18,19,20]. Cardiovascular and cerebrovascular diseases in turn are a major risk factor for neurodegenerative disorders and cognitive impairment in old age [18,21]. These pathways explain that a critically low HDL-C level is related to lower cognitive functioning and faster cognitive decline (such as in memory) in old age [18,22,23,24].…”

Short residence duration was associated with asthma but not cognitive function in the elderly: USA NHANES, 2001–2002

“…The linkage of vascular risk factors (including stroke, heart attack, and diabetes) and late-life cognitive decline has been well established (Tuligenga 2015; Carmichael 2014; Knopman et al 2009) while that of heart failure and cognitive function has been unconfirmed (Cannon et al 2015). Plausible underlying mechanisms might be related to cerebral hypoperfusion or occult cerebrovascular disease, and it seems likely that these may coexist and exert synergistic effects.…”