April 22, 2024

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40% of Dementia Cases are Preventable: Insights from Recent Research

40% of Dementia Cases are Preventable: Insights from Recent Research



40% of Dementia Cases are Preventable: Insights from Recent Research

JAMA Subjournal Review: What You Need to Know About the Latest Evidence!

Dementia is one of the major challenges in global health and social care in the 21st century. About one-third of the elderly (over 65 years old) globally have dementia when they die. It is estimated that by 2050, the number of people with dementia worldwide will exceed 150 million.

Alzheimer’s disease accounts for 60% to 80% of dementia cases, with the remaining being vascular dementia (about 5% to 10%), frontotemporal dementia (3% to 10%), and Lewy body dementia (about 5%), among others. In addition, over 50% of diagnosed Alzheimer’s disease patients have mixed dementia (showing symptoms of both Alzheimer’s disease and vascular dementia).

40% of dementia cases are preventable. A recent publication in JAMA Internal Medicine summarized the modifiable risk factors for dementia and potential prevention measures.

40% of Dementia Cases are Preventable: Insights from Recent Research

screenshot from JAMA Internal Medicine

Age and family history of Alzheimer’s disease are non-modifiable risk factors for dementia. Among them, age is the strongest risk factor for dementia. In addition, a 2020 Lancet Commission report listed 12 modifiable risk factors related to dementia (accounting for about 40% of dementia cases globally), including hypertension, smoking, diabetes, obesity, lower educational level, lack of physical activity, traumatic brain injury, hearing impairment, depression, social isolation, air pollution, and excessive alcohol consumption.

The review emphasizes that although the main evidence for dementia prevention strategies comes from observational studies (with few and somewhat limited randomized clinical trials), intervening in modifiable risk factors in middle-aged or older age may effectively prevent dementia.


Potential prevention measures for dementia:

Cognitive stimulation

The review points out that education level appears to have a significant impact on late-life cognitive levels. However, the results of previous systematic evaluations analyzing the use of “cognitive stimulation” interventions (such as computer cognitive function training) do not necessarily significantly improve the cognitive function of the subjects.

Hearing aids

Meta-analyses of most observational studies show that hearing aids and cochlear implants can reduce the incidence of cognitive decline by 19%. However, the results of a recent 3-year clinical trial on hearing interventions suggest that hearing aids may not effectively prevent cognitive decline.

Treatment of cardiovascular risk factors

The SPRINT MIND trial showed that intensive blood pressure control (systolic blood pressure <120 mmHg) could reduce the incidence of dementia by 17% compared to standard treatment (systolic blood pressure <140 mmHg) (although not statistically significant). At the same time, the risk of secondary endpoints (including mild cognitive impairment [MCI] or dementia incidence) also showed a similar magnitude of reduction and reached statistical significance.

However, the analysis data from Cochrane review does not support the use of statins to reduce the risk of cognitive decline and dementia, and large clinical trials have not confirmed the protective effect of aspirin in preventing dementia.

Dietary adjustments

Observational studies suggest that the Mediterranean diet, DASH diet, and MIND diet (a diet specifically designed for brain health based on the Mediterranean and DASH diets) have a protective effect on brain health. However, a recent clinical trial compared the MIND diet with a control intervention of mild caloric restriction diet, and the 3-year follow-up data showed no significant differences in overall cognitive function or magnetic resonance imaging (MRI) results in the subjects under either diet intervention. The review emphasizes that in most middle-aged overweight and obese people, weight loss is associated with improvements in attention and memory.

Quitting alcohol/smoking

Many studies suggest that moderate alcohol consumption has a certain protective effect on brain cognitive function compared to quitting alcohol. However, some studies also suggest that heavy drinking or alcohol use disorder increases the risk of dementia. In addition, the analysis results of a longitudinal study suggest that smoking cessation is associated with a reduced risk of dementia in the following 8 years.

Treatment of depression

The relationship between depression and dementia is complex. Depression can be a predictive factor for the onset of dementia (including prodromal symptoms of dementia and comorbidities of dementia). Although drug treatment can improve the psychomotor speed and delayed recall ability of depression patients, to date, no randomized controlled trials have confirmed that antidepressant treatment can prevent dementia.

Improving sleep

The analysis results of longitudinal studies show that sleep disorders are associated with an increased risk of all-cause dementia, Alzheimer’s disease, and vascular dementia. In addition, specific types of sleep disorders are also associated with an increased risk of specific types of dementia, including insomnia and Alzheimer’s disease; sleep apnea and all-cause dementia, Alzheimer’s disease, and vascular dementia.

Retrospective observational data suggest that continuous positive airway pressure therapy (for obstructive sleep apnea) can specifically reduce the incidence of dementia and Alzheimer’s disease. Although obstructive sleep apnea is associated with increased levels of cerebrospinal fluid biomarkers in Alzheimer’s disease patients, there is currently no clinical trial evidence to suggest that continuous positive airway pressure therapy can reverse these changes.

Prevention of delirium

Delirium is an acute state of consciousness confusion that can affect 50% of hospitalized adults and 80% of adults in intensive care units. In addition, delirium is a potential modifiable independent risk factor for subsequent dementia onset. Previous studies have shown that delirium is independently associated with cognitive decline in the elderly and can accelerate cognitive decline in dementia patients. It is worth noting that about 50% of delirium cases can be prevented through comprehensive intervention strategies. It is estimated that non-drug methods of delirium prevention can prevent 6 cases of dementia per 1000 patients.

Avoiding social isolation

The analysis results of longitudinal studies show that frequent social contact in middle age and early old age is associated with a reduced risk of dementia onset. An analysis of a systematic review (involving 3 randomized controlled trials and 586 subjects) confirmed that increasing social activity levels can slightly improve some cognitive test results in subjects.

Increasing physical activity levels

The meta-analysis results of observational studies show that exercise is beneficial for preventing Alzheimer’s disease and dementia. In addition, the amount of physical activity per week may also be important. Although current research has not shown a correlation between middle-aged physical activity levels and cognitive abilities, late-life physical activity levels have indeed been shown to be related to cognitive abilities. The results of a randomized controlled trial showed that exercise comprehensive intervention strategies (including strength training) improved the cognitive abilities of subjects (especially those with mild cognitive impairment [MCI]).

Diabetes treatment

The analysis data from Cochrane review shows that intensive glycemic control did not significantly slow cognitive decline in patients compared to standard diabetes management over 5 years.


Beneficial effects of multifactorial interventions on cognitive function

Previous studies have shown that multifactorial comprehensive interventions are beneficial for cognitive function. The 2-year FINGER study showed that comprehensive intervention measures (including diet, exercise, cognitive function training, cardiovascular risk factor management) improved the cognitive function of healthy elderly people at risk of cognitive decline.

In addition, the analysis results of the SMARRT study showed that personalized multifactorial comprehensive intervention can moderately improve patients’ cognitive composite scores, risk factors, and quality of life compared to the control group (intervention was health education).


Conclusion

Although academic researchers have identified many risk factors for dementia, there is still a lack of sufficient research evidence on which path

ogenic pathways and risk factors will be the most effective targets for dementia prevention or drug intervention.

In the past few decades, scientists have identified 75 loci associated with Alzheimer’s disease in genome-wide association studies (GWAS). However, due to the relatively weak effect size, most of these genetic variations lack sufficient evidence to support them as drug targets.

Overall, the Alzheimer’s disease-related genetic variations discovered by GWAS may help us identify individuals at high risk of dementia. By combining individual dementia genetic factors and modifiable risk factors, we may be able to assess high-risk populations for dementia more accurately, thereby developing targeted early intervention strategies.

40% of Dementia Cases are Preventable: Insights from Recent Research

(source:internet, reference only)


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