The adverse effect of modifiable dementia risk factors on cognition amplifies across the adult lifespan

Abstract

Background Reversible lifestyle behaviors (modifiable risk factors) can reduce dementia risk by 40%, but their prevalence and association with cognition throughout the adult lifespan is less well understood. Methods The associations between the number of modifiable risk factors for dementia (low education, hypertension, hearing loss, traumatic brain injury, alcohol or substance abuse, diabetes, smoking, and depression) and cognition were examined in an online sample (N = 22,117, ages 18–89). Findings Older adults (ages 66–89) had more risk factors than middle‐aged (ages 45–65) and younger adults (ages 18–44). Polynomial regression revealed that each additional risk factor was associated with lower cognitive performance (equivalent to 3 years of aging), with a larger association as age increased. People with no risk factors in their forties to seventies showed similar cognitive performance to people 10 or 20 years younger with many risk factors. Interpretation Modifiable dementia risk factors amplify lifespan age differences in cognitive performance.

2023 Alzheimer's disease facts and figures

“…Supporting the importance of modifiable risk factors, a recent study of more than 22,000 individuals age 18-89 found that the cognitive performance of individuals age 40-79 with none of eight modifiable risk factors was similar to that of people 10-20 years younger who had multiple risk factors. 116 Furthermore, another group of researchers found that addressing modifiable risk factors in midlife was associated with decreased risk of dementia even among groups of individuals with a higher genetic risk of dementia. 117 And so, while you cannot change the genes you've inherited, you may be able to influence their effect on cognition by addressing factors you can change.…”

Demand Coupling Drives Neurodegeneration: A Model of Age-Related Cognitive Decline and Dementia

“…This includes significantly increased risk of ARCD and ARD as well as worse cognitive function associated with sedentary behavior and reduced physical activity [ 37 , 41 , 42 , 43 ], chronic sleep deprivation or sleep disruption [ 37 , 44 , 45 ], insulin resistance and dysglycemia [ 46 , 47 ], poor-quality nutrition and associated changes in nutrient status [ 10 , 48 ], body composition [ 49 , 50 , 51 , 52 ], sex hormone status during and after the menopausal transition [ 53 ], and the effect of social isolation and poor social support [ 54 ]. Early evidence is mounting to suggest that lifestyle and environmental modification has the potential to prevent or even reverse ARD, especially when initiated early in the ARCD process [ 10 , 55 , 56 , 57 ]. Though strategies for implementation are beyond the scope of this manuscript, moving focus away from heterogeneous cellular-level pathological processes and onto environmental factors that appear to be the most upstream antecedents of ARCD allows us to better understand the disease process as well as determine intervention points that are likely to translate into reductions in the ARCD and ARD disease burden.…”

Is the lack of appropriate cognitive demand the primary driver of dementia risk?

“…This includes evidence for significantly increased risk of dementia as well as worse cognitive function associated with reduced physical activity, 10,15–17 poor sleep, 10,18,19 metabolic disease, 20,21 nutrient deficiencies, 14,22 hormonal insufficiency, 23 altered body composition, 24–27 and social isolation or poor social support 28 . Early evidence is also mounting to suggest that lifestyle and environmental modification has the potential to prevent or even reverse ARD, especially when initiated early in the disease process 14,29,30 . A prime example of this is the pioneering work by Prof. David Smith and colleagues, who showed that intervention with B vitamins to lower elevated homocysteine slowed the rate of brain atrophy and cognitive decline, particularly in the setting of adequate omega‐3 fatty acid status 22 .…”

“…28 Early evidence is also mounting to suggest that lifestyle and environmental modification has the potential to prevent or even reverse ARD, especially when initiated early in the disease process. 14,29,30 A prime example of this is the pioneering work by Prof. David Smith and colleagues, who showed that intervention with B vitamins to lower elevated homocysteine slowed the rate of brain atrophy and cognitive decline, particularly in the setting of adequate omega-3 fatty acid status. 22 Importantly, the environmental influences on ARD risk map directly to the six evidence-based pillars of lifestyle medicine (Figure 1).…”