Despite much research being conducted into the causes of dementia, many questions remain unanswered.
Current evidence shows that multiple factors contribute to whether a person develops dementia, including age, genes, environment, and lifestyle factors.
However, up to half of the total burden of dementia in Australia may be due to modifiable risk factors.
biomedical risk factors
Risk factors for dementia, like those for heart disease and other chronic diseases, are categorized as modifiable and non-modifiable. The scientific and policy literature identifies modifiable risk factors for some dementia and modifiable risk factors for other major chronic diseases such as heart disease, stroke, chronic obstructive pulmonary disease, diabetes, and some cancers. Significant associations between the risk factors have been documented. The WHO recently reviewed the evidence on risk factors and provided the following information: Reducing the risk of cognitive decline and dementia guidelines For preventive interventions where the evidence is considered sufficiently strong. We found sufficient evidence regarding the following risks: Some dementia risk factors are similar to those for other major chronic diseases, such as heart disease, stroke, COPD, diabetes, and some cancers.
Lack of exercise
Physical activity has many health benefits and is an important modifiable factor involved in the development of many chronic diseases, including dementia. There is evidence that the highest levels of physical activity are the most protective and may have direct beneficial effects on brain structure. Indirectly, it has been suggested that the effects of physical activity on brain health result from its potential effects on cardiovascular risk factors, including hypertension, insulin resistance, high cholesterol, and other biological mechanisms. . Therefore, maintaining physical activity levels and muscle mass, strength and function throughout the lifespan has the potential to reduce the prevalence of dementia and prevent (or slow) cognitive decline in the Australian population. there is.
smoking
Tobacco remains the leading cause of preventable death worldwide and generates billions of dollars in health and welfare costs. Smoking is a major risk factor for many chronic diseases, including heart disease, respiratory disease, and many cancers. A growing body of evidence highlights the link between smoking in midlife and later disorders such as cognitive decline and dementia. There is ample evidence of the effectiveness of smoking cessation interventions in reducing all these health risks.
nutrition
A healthy diet is important not only for optimal health throughout life, but also for the prevention of chronic diseases, including those that increase the risk of dementia. There is evidence that diet may be directly and indirectly involved in the development of dementia through its effects on other risk factors. A series of high-quality studies has shown that adhering to high levels of the Mediterranean diet, which includes intake of fruits, vegetables, fish, nuts, olive oil and other unsaturated fats, whole grains, and coffee, is associated with improved cognitive performance. They conclude that this may be associated with decreased cognitive performance. Incidence of dementia.
alcohol
There is growing evidence of the complex relationship between alcohol use and cognitive health and dementia. Previous reviews have indicated that light to moderate alcohol consumption may have beneficial effects on cognitive health. However, even moderate amounts of alcohol have been shown to have negative effects on brain structure, and heavy drinking has a negative impact on the risk of developing dementia, regardless of the type of dementia. Increasing evidence supports the claim that heavy alcohol consumption (more than 12g per day) is associated with an increased risk of dementia. Alcohol use disorder is characterized by harmful chronic alcohol consumption. People who consume harmful amounts of alcohol are three times more likely to develop early-onset dementia. Alcohol use disorder is also associated with a variety of related risk factors for dementia, including smoking, poor nutrition, and physical inactivity.
weight management
Overweight and obesity pose a direct risk for a wide range of chronic diseases, including type 2 diabetes and cancer. These are also indirect risks for other cardiovascular risk factors such as high cholesterol and high blood pressure. There is evidence that obesity in midlife increases the risk of dementia later in life.
diabetes management
Diabetes in later life is associated with decreased cognitive function and increased risk of dementia. Additionally, secondary health problems that arise from diabetes, such as kidney disease, eye disease, hearing loss, and cardiovascular disease, are all associated with an increased risk of dementia. There is still inconsistent evidence regarding the direct effects of glycemic control interventions on cognitive outcomes. There is evidence that treating diabetes-related cardiovascular disease may reduce the risk of dementia.
Management of high blood pressure
High blood pressure in midlife is associated with an increased risk of dementia later in life. There is still no established evidence that lower blood pressure after middle age directly affects later cognitive decline and dementia. However, it is clear that lowering high blood pressure is highly beneficial in reducing cardiovascular disease and premature mortality, and thus improving the overall health of older adults.
cholesterol management
Dyslipidemia (high cholesterol) is an important modifiable risk factor and is associated with one-third of the global burden of heart disease and premature death and disability. Although many epidemiological studies have found an association between high cholesterol and dementia, this has not yet been conclusively proven. Other studies have confirmed the link between cholesterol control and reduced dementia risk.
A summary of WHO recommendations for each of these risks is provided in Appendix 1.
Many studies, including the Lancet Commission, have identified these as additional modifiable risks for cognitive impairment and dementia, while the WHO provides guidelines for the management of depression and midlife hearing loss. not.
social risk factors
The World Health Organization guidelines do not address the influence of broader social determinants on dementia risk. However, many other studies have investigated and described the inverse association between socioeconomic status and chronic diseases such as cardiovascular disease (CVD) and dementia. Although the biological and other pathways that cause these symptoms are known, their cumulative effects are not well understood. The social gradient in CVD persists even after controlling for health behaviors and clinical indicators, suggesting that other processes are involved.
Immune responses to chronic ‘social stress’ may explain some of the socioeconomic gradients in CVD and other inflammation-related conditions, including dementia. Adding some support to this argument, there is some evidence that social interventions, particularly promoting higher education attainment, may have protective effects. Those who dropped out of high school before the 8th grade had a 2.2 times higher risk of developing dementia later in life, and those who dropped out between 8th and 11th grade had a 1.5 times higher risk than those who left high school. It will be doubled. There is growing evidence that loneliness and isolation are associated with cognitive decline in older adults. Interventions to reduce social isolation, promote social participation, and increase physical activity levels in older adults reduce the risk of dementia. Interventions that promote social connectedness may be particularly beneficial for individuals with lower levels of education. Furthermore, hearing loss is associated with both social isolation and the incidence of dementia.
The Lancet Commission found that the protective effects of education and social engagement are associated with varying levels of “cognitive reserve” (brain resilience), which is strengthened by early childhood experiences such as education and intellectual stimulation. suggests. There is evidence that high socio-economic status during pregnancy and early childhood is protectively associated with dementia risk later in life.
