Dementia risk factors related research

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This is an advanced reading page for interested readers. It contains a detailed discussion on the risk factors and preventive factors for dementia. It discusses how to make sense of the various reports we read on the topic. If you want an overview on dementia risk, please check the section Risk factors for dementia and what we can do of our page on diagnosis.

The idea of getting dementia is frightening for most of us. Unfortunately, media articles give confusing information. Sometimes we hear that dementia can happen to anyone. At other times, an article claims that we can prevent dementia by eating a particular herb or doing some particular activity. We want to stay safe from dementia but we don’t want to do things that don’t work or may even harm us.

This page contains detailed discussions for readers trying to understand the risk factors for dementia, and want to reduce their chance of dementia by making suitable changes in their diet, exercise, and daily activities. The page does not discuss ongoing research and studies. Persons interested in the latest research should subscribe to reliable research sites.

Sections on this page:

Basic understanding of terms like risks, prevention, correlations, causation, etc.

Dementia risk reduction is often discussed using words like “prevention”, “risk reduction”, “risk factors”, and “protective factors.” Articles often use these terms in different ways. Sometimes there are contradictions within the same article.

Popular media use of the word “prevention” is misleading. Most people use “prevention” to mean that the chance of getting something has dropped to zero. When an article headline says: “Do this one thing to prevent dementia” readers think the author is assuring them that they will never get dementia if they do that activity regularly. Such articles often quote a study to support the claim, making the claim seem scientifically proven. But this is wrong as a single study cannot be used to make such a drastic claim.

Some standard, authoritative dementia and Alzheimer’s sites are meant for individuals. These discuss what people can do to reduce their risk of dementia. They do not claim that there is any certain way for an individual to remain safe from dementia. The Alzheimer’s Association page Prevention and Risk of Alzheimer’s and Dementia Opens in new window says (web-page quote reconfirmed Feb 2024):

Researchers around the globe are exploring how to prevent Alzheimer’s. While Alzheimer’s prevention has no definitive answers at this time, research has shown that we can take action to reduce our risk of developing it.

Some scientific papers and published reports look at dementia incidence and prevalence at a population level. Such reports and also policy makers use the word “prevention” in the context of entire populations (not individuals). The focus is delaying dementia onset for the population on an average. Chapter 1 of World Alzheimer’s Report 2014: Dementia and Risk Reduction: An analysis of protective and modifiable factors Opens in new window explains this. A quote:

…prevention of dementia is commonly conceived as the delay of the clinical onset of the disease rather than a slowing or avoidance of the development of the underlying neuropathology. Similar to other chronic diseases primary prevention of dementia corresponds, ideally, to ‘delay until death’ of symptomatic onset, or, failing that, a delaying or deferring of onset to older ages than that at which it would otherwise have occurred. An average five year delay in the age of onset would tend to reduce population prevalence by 50%, hence greatly reducing its impact in the general population.

The report explains that the global burden can be tackled by delaying dementia onset at a population level. They do not use “prevention” for what individuals can do to completely avoid dementia. The report says:

There is no evidence strong enough at this time to claim that lifestyle changes will prevent dementia on an individual basis.

Population-level dementia risk reduction interventions should be seen along with other health-based recommendations. As the WHO May 2019 report, Risk reduction of cognitive decline and dementia: WHO Guidelines Opens in new window points out in its foreword,

As many of the risk factors for dementia are shared with those of non-communicable diseases, the key recommendations can be effectively integrated into programmes for tobacco cessation, cardiovascular disease risk reduction and nutrition.

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Finding ways an individual can completely avoid dementia is very unlikely; we therefore must try to reduce the risk of dementia

Cognitive decline occurs due to an accumulation of many factors. The report referred to earlier, World Alzheimer’s Report 2014: Dementia and Risk Reduction: An analysis of protective and modifiable factors explains this. A quote:

…marked inter-individual differences in cognitive health in late-life are observed at a population-level. These differences may in part be a function of the level of exposure to a number of factors across the entire life course and are usually termed risk or protective, depending on whether, in general, they are associated with an increased or reduced future likelihood of cognitive impairment and dementia in populations.
…..
Because the clinical onset of dementia is likely to be the end stage of the accumulation of neuropathological damage over several years, the latency between the initiation of the process and detection of the onset of dementia is likely to be very long.

Dementia symptoms happen because of many factors, and their impact grows over time. This impact then crosses a threshold where the symptoms are visible. Keeping this in mind, it is clear that any simplistic suggestion like ‘do a su-do-ku a day and keep dementia at bay’ cannot be correct.

Also, many medical conditions can cause dementia symptoms. Even if researchers find a way to avoid one medical condition, that does not safeguard an individual against all other conditions that can cause dementia. For example, even if researchers find how to completely avoid all variations of Alzheimer’s Disease, the individual can still get one or more of the several other dementia-causing diseases. So an article that keeps using “prevent Alzheimer’s” interchangeably with “prevent dementia” is clearly suspicious. Also, research has not yet shown any way to prevent Alzheimer’s in an individual.

As prevention is not possible, we, as individuals, need to look at ways to reduce our risk of getting dementia. We can do this in two ways: (1) reduce or cut out known risk factors (2) increase factors that are known to be protective.

Many risk factors are non-modifiable, that is, beyond our control. So we focus on information on modifiable risk factors to reduce our individual probability of developing dementia. These are often considered in four key domains: developmental, psychological and psychosocial, lifestyle and cardiovascular conditions.

We also need to know if we have an increased risk of dementia because of factors beyond our control. If our risk is higher, we will be more careful about factors that we can still control. For example, many risk factors are associated with the stage of life, like childhood development. Adults cannot change their childhood development. But if they realize that their risk of dementia is higher because of their childhood, they will be more careful about avoiding risk factors now. They will also adopt more protective measures. Research on dementia risk factors is ongoing. Individuals who understand the conclusions can make better choices.

Prioritization matters. Given our busy lives, we cannot follow every “good” advice we get. We have to see what may be effective and practical for us. We cannot waste effort and energy on dramatic, misleading headlines, or change our actions just because of a single study. After all, the results of a single study may be rejected in later studies. We should not get misled by claims about a miracle cure by someone selling that alleged cure.

This page discusses ways to consider available data, and includes suggestions of sites where analysis of multiple studies and claims may be seen.

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Consolidated suggestions on risk factors, as available in published reports and authoritative sites

Scientists look at results of multiple studies to identify risk factors and protective factors. This is called a meta study. A specific study may find a correlation of a factor with dementia, but this may be a “false positive” or a “false negative.” The result may also be because of a flaw in the experiment design or a bias in the sample. Authoritative bodies therefore look for results that are proven in multiple studies, to make sure that their recommendations are reliable.

Here are some web resources of national and international Alzheimer’s Disease associations and research bodies:

Here are some important published reports on risk reduction (chronological order):

  • In February 2014, Alzheimer’s Disease International (ADI) published a report, “Nutrition and dementia: A review of available research Opens in new window“. This report discusses the role of right nutrition in the life of persons with dementia. It reviews dietary factors across the life course in terms of the risk of late onset dementia. It includes suggestions on nutrition-related actions.
  • In September 2014, Alzheimer’s Disease International (ADI) published a landmark report, World Alzheimer’s Report 2014: Dementia and Risk Reduction: An analysis of protective and modifiable factors Opens in new window. This report presents a meta analysis of published research. It offers conclusions regarding factors correlated with dementia at a population level, and includes whether the correlation is strong enough to explore through more studies. It suggests Governmental level actions to “prevent” (delay the onset of) dementia at a population level. (See explanation of “prevention” above.) It does not suggest how individuals can reduce their own dementia risk. However, the insights can be interesting for readers who want to understand more.
  • In May 2019, World Health Organization (WHO) published a 96 page report with evidence-based guidance for a public health response to dementia. It includes recommendations on lifestyle behaviours and interventions to delay or prevent cognitive decline and dementia, and is intended as a tool for health care providers, governments, policy-makers and other stakeholders to strengthen their response to the dementia challenge. The recommended interventions are identified as strong or conditional. Strong interventions are those that most individuals would want and should receive, and conditional recommendations are those where different choices may be appropriate for individuals and they may need help to decide. The report can be seen at: Risk reduction of cognitive decline and dementia: WHO Guidelines Opens in new window .
  • The Lancet Commission on Dementia Prevention, Intervention, and Care has been publishing reports consolidating expert opinion on the emerging knowledge of how to prevent and manage dementia. These include key messages of the commission as well as supporting discussions, data, and references. The 2017 report Dementia prevention, intervention, and care (2017)Opens in new window listed 9 modifiable risk factors. Later, in August 2020, an updated report was published adding three risk factors to those identified in 2017. See Dementia prevention, intervention, and care: 2020 report of the Lancet Commission Opens in new window. I August 2024, another updated version was published, adding 2 more modifiable risk factors, bring the list to 14. These are less education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, low social contact, excessive alcohol consumption, traumatic brain injury, air pollution, high LDL cholesterol and vision loss. The report states that “The potential for prevention is high and, overall,nearly half of dementias could theoretically be prevented by eliminating these 14 risk factors.” See the 2024 report : Dementia prevention, intervention, and care (2024 reoport) Opens in new window .

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Evaluating media reports related to ongoing Alzheimer’s/ dementia research findings

Newspapers and magazines often carry reports of apparently sensational studies. They may even publish a contradictory report a few days later. This is very confusing for persons trying to decide on life changes to make. Remember that media reports are often misleading. Headlines, especially, are dramatic and written mainly to attract readers. The article may be written in a hurry. It may not be a correct summary of the scientific paper it quotes. Also, newspapers often sensationalize the results of a single study, and don’t bother about whether the claims are supported or replicated by other studies.

Before changing your lifestyle because of a result that gives “hope,”consider evaluating the report:

One type of recommendation is taking some specific herb or food supplement. Impressive claims are made in a few articles, which are then duplicated across multiple Internet articles and seem all over the Internet. Here are some useful ways to verify claims:

To stay in touch with published results, here are some websites to consider. (You will need to be careful about how to interpret the results):

Some published papers may be on medication. When reading research findings, remember that it takes many years for preliminary research results to result in medicines or detection methods that can be used for humans.

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Deciding on lifestyle choices

Many persons assume that “there is no harm” trying out a diet change suggested in a news article, even if the report mentions only one study showing a particular correlation. Scientifically speaking, however, results can be considered reliable only if they are confirmed in multiple studies.

Our bodies are very complex. what may work for one person may not work for another and may even harm. So if one person reports on the Internet that something worked for her loved one, it cannot be assumed to be effective or even safe for others. Even herbs can harm us. They may not suit us. They may be toxic when consumed in larger quantities, may conflict with our other medicines or may make our other medical problems worse. Before changing diet and lifestyle, please discuss with a doctor who knows your medical history, family history, and current medicines.

There are many reasons to be cautious even for apparently “harmless” decisions. We can make only limited number of changes in our lives. Each change we make is an effort for us. If we make changes that do not help (or which can actually harm), we may miss better and more useful changes.

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Data on some modifiable factors currently under discussion

While there is no certain way to prevent or delay dementia, and research is still underway for solutions, some choices are worth considering even if not fully proven.

Tobacco use and dementia:

The International Journal of Geriatric Psychiatry, published a study linking dementia and tobacco: Tobacco use and dementia: evidence from the 1066 dementia population-based surveys in Latin America, China and India Opens in new window. Smoking has been mentioned as a possible causal factor in the World Alzheimer’s Report 2014: Dementia and Risk Reduction: An analysis of protective and modifiable factors. The summary states that : “The strongest evidence for possible causal associations with dementia are those of low education in early life, hypertension in midlife, and smoking and diabetes across the life course.” There is also a WHO publication TOBACCO & DEMENTIA (PDF file) Opens in new window that recommends quitting smoking; Some quotes:

Smoking is a risk factor for dementia, and quitting could reduce the dementia burden
…Second-hand smoke exposure may also increase the risk of dementia
…14% of Alzheimer’s disease cases worldwide are potentially attributed to smoking

Brain plasticity, memory training, and dementia

Earlier it was believed that we are born with a fixed number of brain cells and that no new brain cells are created during our lifetimes. But we now know that we can grow new neurons and retrain our brains. Research is being done to see whether training the brain can delay or prevent dementia, on which types of brain exercises are effective and for what, and how much such exercise is recommended. Researchers are interested in seeing if software programs and video games can help reduce the risk of dementia, especially as there are several commercial products for “brain training.” When looking at the ink between cognitive activity and dementia, they are also considering whether a reduction in cognitive activity could be happening because the person is already in the initial stages of dementia.

An important, relevant concept here is the possible advantage of Cognitive Reserve. (See Wikipedia page on cognitive reserve Opens in new window). Education helps building more cognitive reserve. This may explain the findings that higher education in early years correlates to lower dementia. It may also explain the claims on the benefits of bilingualism (Published papers: Delaying the onset of Alzheimer disease: bilingualism as a form of cognitive reserve Opens in new window, Bilingualism delays age at onset of dementia, independent of education and immigration status Opens in new window). If bilingualism is protective, that may be good news for Indians, as many people here know multiple languages. They can choose to actively speak more than one language and acquire the claimed protection. The World 2014 report states:

Brain and cognitive reserve, developed early in life and consolidated in midlife may buffer the expression of symptoms of dementia in the presence of neurodegenerative disease.

So far, the recommendation is to maintain a good level of intellectual activity and social connection through a range of activities and participation. The cognitive stimulus needs to be broad-based. It should not be confined to a few specific activities.

Discussion on possible preventive aspects of brain training and remaining mentally and socially active can also be see on Alzheimer’s Association (USA) site page on risks and prevention, Prevention and Risk of Alzheimer’s and Dementia Opens in new window and The Alzheimer’s Society UK’s page Brain Training Opens in new window. In general, so far, it seems such training helps in some limited areas and help be better at some tasks, but specific recommendations are not yet available, and such training is not a magical bullet to either prevent or reverse dementia. More studies are needed. There is still not clear evidence regarding the effectiveness of commercial brain training products.

Commonly discussed factors, myths, and data:

There are also many other typical articles in media with claims of both risk and protective factors, that are not yet confirmed by research, though some are the subject of many studies and hopefully out understanding will improve with time. In some cases, while the active ingredient of some herb/ product has shown some good results in preliminary studies, it is unclear how effective these can be, at what dosage and with what cautions, and whether the benefits can only be obtained by using an extract or can also be obtained by taking the herb directly. In some cases, claims rampant in media are based on dramatic anecdotal cases, but no studies have shown any benefits so far. Some are more speculative interpretations of potential risk not based on science, or potential “hope” based on speculation again. Please do not consider any diet change based on a new s report as “it can’t harm anyway” as some such additions may lead to escalation of various health conditions and even cause toxicity.

As more and more studies are done and results combined to get a better understanding, it is best to check the current status by using authoritative sources that consolidate the insight obtained from various studies, and are not swayed by sensationalism.

  • Coconut oil: Coconut oil is used in many Indian homes. News that coconut oil may help in dementia is seen as a practical measure that can be used right away. The Internet has several articles on the alleged benefits of coconut oil. Most are related to the videos and presentations of Dr. Mary Newport. Dr. Newport is neonatologist who reported that her husband showed significant improvement for some time by using coconut oil for a “ketogenic diet.” She offered her scientific impression of why this must have worked. Her personal experience is often shared and assumed by laypersons to be sufficient proof that anyone can benefit from adding coconut oil. However, currently evidence does not support this, and coconut oil consumption as recommended can even harm. A demystification of coconut oil with respect to dementia is available at the Alzheimer Society UK’s page: Coconut oil and dementia Opens in new window, and in a blog entry on Alzheimer’s Research UK page: Coconut Oil for Alzheimer’s: Separating Fact from Fiction Opens in new window.
  • Turmeric (Haldi) and its extracts curcumin and turmerone: Numerous popular press articles claim that turmeric (haldi) consumption in food can protect from Alzheimer’s. This especially interests Indians because turmeric is a common spice in Indian cooking. Curcumin, an extract of turmeric, is being studied for its possible protective effect. Turmerone, too, is being studied. But so far, it is not confirmed whether dietary turmeric is protective, and also unclear whether (and how much) supplementation would be effective. Some discussion/ papers at: this pageOpens in new window and this published paper Opens in new window.
  • Cannabis, Cannabis oil, CBD oil: Some articles claim that cannabis can prevent/ treat dementia or help with its symptoms. Some research has been done on cannabis, but while some initial benefits have been seen, it is not recommended yet as there is no clarity on required dosage and no data on safety, long term effects/ side effects. The Alzheimer Society UK’s page: Cannabis, CBD oil and dementia Opens in new window explains this. Another relevant document is this paper (PDF file) Opens in new window which explains the current understanding, links to several references, and states (checked February 2024), There is currently a very limited evidence base for medicinal cannabis in treatment of or behavioural management of patients with dementia or Alzheimer’s disease….The current limited evidence does not support a therapeutic effect of medicinal cannabis for management of behavioural disturbance in dementia.
  • Possible risk of aluminium, silver dental fillings/ amalgam, flu shots, aspartame: They are debunked here: Alzheimer’s Myths Opens in new window.

Diet, supplements and dementia:

While overall there is no firm evidence about how dementia risk can be reduced by diets and supplements, this is an area of ongoing research. In general,the Mediterranean diet is recommended as it may be protective of the brain, though studies are still underway to confirm this. This diet is also associated with better outcomes on many other parameters, such as lower risk of stroke, type 2 diabetes, cardiovascular problems, etc. Another diet mentioned n tis context is the MIND diet, which combines features of the Mediterranean diet and the DASH diet. . Also, it seems that a normal diet that contains enough good nutrients like vitamins and supplements would be useful, but supplements may be be effective.

Discussions on diet, anti-oxidants, and supplements can be seen on this page of Alzheimer’s Society UK: Diet and dementia Opens in new window.

Published reports, include Nutrition and dementia: A review of available research (ADI) published in February 2014, which reviews dietary factors across the life course in terms of the risk of late onset dementia and includes suggestions on nutrition-related actions: Nutrition and dementia: A review of available research Opens in new window. Another important report is the World Alzheimer’s Report 2014 (mentioned above) , which contain discussions on evidence (or otherwise) of nutrients and supplements with respect to dementia.

While no firm recommendations have been made about diets that can prevent / reduce dementia risk, and many studies have not supported the benefits shown in other studies, designing good studies around diet is very challenging. The following papers may be worth a look: MIND diet slows cognitive decline with aging Opens in new window, MIND Diet Associated with Reduced Incidence of Alzheimer’s Disease Opens in new window, The Nordic Prudent Diet Reduces Risk of Cognitive Decline in the Swedish Older Adults: A Population-Based Cohort Study Opens in new window, Diet’s Role in Modifying Risk of Alzheimer’s Disease: History and Present Understanding Opens in new window. Note that the Lancet Commision is not yet suggesting any specific diet approach for risk reduction because the evidence is not yet considered clear and convincing .

A recent paper on lifestyle reversing Alzheimer’s is also interesting: Effects of intensive lifestyle changes on the progression of mild cognitive impairment or early dementia due to Alzheimer’s disease: a randomized, controlled clinical trial Opens in new window.

Common health problems and their control:

Healthy ageing is supposed to help for a healthy brain. One possible way to reduce the chance of dementia is to avoid major health problems or keep them under control. For example, multiple reports on risk factors for dementia have highlighted the impact of problems like diabetes and hypertension, finding correlations strong enough to recommend extra caution to avoid and/ or control such conditions.

For example, the World Alzheimer’s Report 2014 suggests a strong and consistent association between diabetes (mid life and late life) with dementia (especially vascular dementia) , and that the duration of diabetes may be an important risk determinant. Hypertension in midlife also increases the risk of dementia, particularly vascular dementia. Compared to these,evidence linking obesity and dyslipidemia is relatively inconsistent and weak. In general, it suggests that cardiovascular aspects are important and that a good mantra is “What is good for your heart is good for your brain.”

The Lancet Commission on Dementia Prevention, Intervention, and Care has published reports listing the modifiable risk factors based on research and evidence. The 2017 report listed 9 modifiable risk factors, which was expanded to 12 in 2020 based on new convincing evidence, and then to 14 modifiable risk factors in 2024. The 2024 report can be seen at Dementia prevention, intervention, and care: 2024 report of the Lancet Commission Opens in new window The current list of 14 is: less education, hearing loss, hypertension, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption [ie, >21 UK units, equivalent to >12 US units], traumatic brain injury [TBI], air pollution, social isolation, untreated vision loss and high LDL cholesterol.

Common lifestyle advice:

In addition to advice on health problems that are associated with dementia and which we should try to prevent/ control, the key recommendations of the Lancet reports include several specific lifestyle advice for risk reduction, e.g., steps to ensure better education, addressing hearing impairment, quitting smoking, remaining physically active, staying socially connected, avoiding excessive alcohol consumption, avoiding traumatic brain injury, avoiding air pollution, treating vision loss, and controlling high LDL cholesterol.

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