Introduction
Recent findings
Non-modifiable risk factors for dementia
Modifiable risk factors (lifestyle factors) for dementia
Conclusion
References

 

 

 

 

 

Introduction

Dementia, including Alzheimer’s disease, remains one of the biggest global public health challenges facing our generation. There are some 800,000 people with dementia in the UK,1 with the burden falling on over-stretched social care services, the NHS and families. This number is expected to rise to over 1.7 million people by 2051.2 Dementia is one of the main causes of disability in later life in the UK, with symptoms including memory loss, confusion, problems with speech, understanding and control of emotions.

Dementia costs the UK economy £23 billion a year, while the worldwide cost in 2010, most of it in G8 countries, was estimated to be $604 billion (£365 billion) and the cost in low income countries is projected to grow significantly. Given this epidemic scale, and with no known cure, it’s crucial that we look at what we can do to reduce the risk or delay the onset of developing the disease.

In December 2013, the G8 nations—Canada, France, Germany, Italy, Japan, Russia, the UK, and the US—created the World Dementia Council (WDC)3 to provide global advocacy and leadership on key dementia challenges. One of the WDC’s priority areas is potential risk reduction, both in the absence of treatments and after the time at which a treatment or treatments become available. However, the WDC also recognised that any public health effort to address the risk factors of cognitive decline and dementia must be grounded in the scientific evidence and informed by the scientific literature. Both the World Health Organization and the G8 Dementia Summit of 2013 have stressed the need for prevention to curb the rapidly growing dementia epidemic.

 

Recent findings

Findings from a two-year study4 of more than 1,200 60 to 77-year-olds in Finland revealed that the group who received thorough advice about diet, regular exercise sessions, brain training and health check-ups performed better in cognitive tests than the group who received only the standard medical advice.

The goal of the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), a proof-of-concept, randomised controlled trial, was to determine the impact of a multifaceted intervention aimed at preventing cognitive decline in at-risk elderly persons in the general population. Targeting multiple lifestyle factors, including physical activity, diet, vascular risk factors, and brain training, slowed cognitive decline among older healthy individuals in the first randomised controlled trial of its kind. Two meta analyses studies5,6 found that up to half of all dementia cases may be attributable to inactivity and vascular factors. They have both shown, in their meta-analyses studies, that aerobic physical activities that improve cardiorespiratory fitness enhance cognitive performance in sedentary older adults.

Lifestyle factors, such as poor diet and physical and cognitive inactivity, are thought to be associated with the risk of dementia.7 These factors may be useful targets for the prevention of cognitive impairment and dementia.

The Alzheimer’s Association believes there is sufficient evidence to support the link between several modifiable risk factors and a reduced risk for cognitive decline, and sufficient evidence to suggest that some modifiable risk factors may be associated with reduced risk of dementia.8

The Promoting Brain Health: Developing a prevention agenda linking dementia and noncommunicable diseases meeting was held in London in 2014. It involved some 60 leading figures in dementia and non-communicable disease (NCD) prevention—the first gathering of its kind—to discuss ideas for a primary prevention agenda on dementia. It concluded that while dementia might not be wholly preventable, like some other NCDs, it has some risk factors that are modifiable, and there is sufficient evidence to justify acting now on these.9

A comprehensive review of international research literature has identified that there are currently several factors that may protect a person from developing Alzheimer’s disease or delay its onset.10

NICE launched new recommendations in 2015 on approaches in mid-life to delay or prevent the onset of dementia, disability and frailty in later life. It concluded by changing specific risk factors and behaviours it is possible to reduce the risk of dementia, disability and frailty for many people.11

 

Non-modifiable risk factors for dementia

Age is the most important risk factor for cognitive decline and dementia.12 In addition, only a small proportion of dementia cases are thought to be directly inherited or caused by identified individual gene mutations.

 

Modifiable risk factors (lifestyle factors) for dementia

Brain

Mental activities
These include improvements in immediate and delayed recall.13,14

Social activities
Some individual studies have shown that higher social interaction in later life is associated with lower risk of developing cognitive impairment.15,16

Years of education
Among potentially modifiable risk factors, the most consistent evidence highlights years of formal education.17,18

Depression
Meta-analyses of cohort and longitudinal studies, as well as additional cohort studies, have shown a history of depression increases the risk for dementia.19,20

Sleep
Several cohorts and observational studies link sleep disturbances (for example, insomnia and sleep apnoea) to increased risk for cognitive decline.21,22

Brain injury
A brain injury increases the risk of developing certain forms of dementia.23,24

 

Body

Physical activities
Several randomised controlled trials and a Cochrane review of such trials have found that inactive, but otherwise healthy, seniors who begin an exercise programme experience significantly improved cognitive function.25,26

Diet
A few cohort studies on the Mediterranean diet (relatively little red meat with an emphasis on whole grains, fruits and vegetables, fish, nuts, and olive oil) or a combined Mediterranean-DASH (Dietary Approaches to Stop Hypertension) diet suggest an association between these diets and reduced risk.27,28

Alcohol
Meta-analyses of prospective and case control studies of older adults suggest small or moderate alcohol consumption by older individuals may decrease the risk of cognitive decline and dementia.29,30 The evidence is not strong enough, however, to suggest those who do not drink should start drinking, especially when weighed against the potential negative effects of excessive alcohol consumption, such as an increased risk of falls among older adults.31,32

Smoking
One study of a large multi-ethnic cohort found heavy smoking in middle-age as much as doubled the risk of later-life dementia.33 Quitting smoking may reduce the associated risk to levels comparable to those who have not smoked.34,35,36

 

Cardiovascular

Diabetes
Some evidence suggests diabetes increases dementia risk not only through vascular pathways and interactions of other biological mechanisms related to diabetes itself.37,38

Mid-life obesity
Studies found that mid-life obesity is associated with an increased risk of dementia. Most postulate this is a strong link, especially with regard to cognitive decline.39,40,41,42 The association may change with age, as being overweight and, even possibly being obese in later life has been associated with reduced risk of dementia.44,45

Others
Mid-life hypertension and hyperlipidaemia (elevated cholesterol) are other risk factors.

 

Conclusion

There is accumulating evidence from observational and experimental studies on how modifiable risk/ protective factors may relate to the pathological hallmarks of Alzheimer’s disease (ie. extracellular amyloid-β plaques and intracellular microtubule p-tau protein neurofibrillary tangles) as well as to the inflammatory and vascular components, of all types of dementias.20,47 The evidence has now reached a point that it can no longer remain simply an exercise in academic discussion. The public should know what the science concludes: certain healthy behaviours known to be effective for diabetes, cardiovascular disease, and cancer are also good for brain health and for reducing the risk of cognitive decline.

The evidence seemed to indicate that mid-life might be a particularly important period to target and there were suggestions that people at this stage of life might be especially receptive to welltargeted advice and interventions about delaying or preventing a process of cognitive decline.

Ideas put forward at the end of Promoting Brain Health meeting, May 2014, included screening and treatment by GPs for mid-life hypertension, screening for cognitive deficit at regular intervals over the age of 60 and making it routine in memory clinics to take blood samples to test for risk factor markers.

Based on the evidence, brain health promotion messages should be integrated in public health promotion campaigns such as anti-tobacco or noncommunicable disease (NCD) awareness campaigns, with the message that it’s never too late to make these changes. This report strongly suggests that dementia needs to be included on World Health Organization (WHO) and national NCD planning.47 To sum up, a good mantra is: “What is good for your heart is good for your brain.”

 

Dr Amir Sajjadi, Consultant Psychiatrist for the Elderly & Dementia Pathway Locality Lead Consultant, South West Community Mental Health Team, Tees, Esk and Wear Valleys NHS Foundation Trust

Professor Stephen Curran, Consultant in Old Age Psychiatry & Clinical Lead. Ground Floor, Modular Accommodation, Wakefield BDU, Fieldhead. Wakefield

Conflict of interest: none declared.

 


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