Dementia is often regarded as an unavoidable consequence of getting older. But a growing body of research is challenging that assumption, suggesting that what people do throughout their lives may significantly influence their chances of developing cognitive decline and dementia.
Several studies have found strong associations between dementia and factors such as high blood pressure, obesity, diabetes, smoking, physical inactivity and depression. These are particularly important because, unlike age and genetics, many of them can be modified.
The evidence does not mean that dementia is simply a lifestyle disease, nor that anyone who develops dementia has somehow caused it through poor choices. Dementia has multiple causes, and age, genetics, brain diseases and other biological factors remain important.
However, researchers increasingly believe that protecting the brain may begin decades before memory problems become noticeable.
The six factors receiving particular attention
Among the lifestyle and health factors repeatedly linked with dementia are hypertension, diabetes, obesity, physical inactivity, smoking and depression.
The Alzheimer’s Association’s latest facts and figures also emphasizes that dementia develops through multiple interacting causes. Age, genetics and family history cannot be changed, but a number of risk factors can potentially be modified.
Let’s look at why these six matter.
1. High blood pressure
Hypertension may be one of the most important modifiable threats to long-term brain health.
The brain depends on an extensive network of blood vessels to deliver oxygen and nutrients. Persistently elevated blood pressure can damage those vessels over time, increasing the risk of strokes and other forms of cerebrovascular damage that can contribute to cognitive impairment.
Research from England found hypertension was the leading modifiable risk factor for dementia during the period studied, accounting for an average population-attributable fraction of about 8.2%. Obesity, social isolation, hearing loss and depression were among the other major contributors.
The implication is important: controlling blood pressure may be doing more than protecting the heart. It may also be protecting the brain.
That means regular blood-pressure checks, physical activity, maintaining a healthy weight, moderating salt intake and taking prescribed medication when necessary can all form part of a broader brain-health strategy.
2. Diabetes
Diabetes is another condition increasingly connected with cognitive decline.
Persistently elevated blood glucose can damage blood vessels and affect multiple organs, including the brain. Diabetes is also closely connected with other dementia risk factors, including obesity and cardiovascular disease.
The 2026 Alzheimer’s disease facts and figures report identifies diabetes among the major potentially modifiable risk factors for dementia.
This does not mean that having diabetes automatically leads to dementia. Rather, good management of blood sugar and cardiovascular health may help reduce the overall risk.
For people living with diabetes, regular medical monitoring is therefore important not only for the kidneys, eyes and heart, but potentially for the brain as well.
3. Obesity
Carrying excessive weight, particularly during midlife, has repeatedly emerged as a dementia risk factor.
Researchers believe obesity may contribute through several pathways, including inflammation, insulin resistance, cardiovascular disease and high blood pressure.
Interestingly, midlife may be particularly important.
The Alzheimer’s Association notes that factors such as midlife obesity and hypertension can influence dementia risk later in life.
This is one reason experts increasingly view dementia prevention as something that should begin long before old age.
Waiting until someone reaches their 60s or 70s to start thinking about brain health may mean missing an important window for prevention.
4. Physical inactivity
The brain is not separate from the rest of the body.
Regular physical activity improves cardiovascular health, helps regulate blood sugar and weight, and can contribute to better overall brain health.
A recent analysis cited in Alzheimer’s Association research found that physical inactivity was among the important modifiable contributors to dementia. Another large study found that transitioning toward healthier lifestyles was associated with lower dementia risk and less hippocampal atrophy.
The hippocampus is particularly important because it plays a central role in learning and memory.
You do not necessarily need an expensive gym membership to become more active. Walking, cycling, swimming, gardening, dancing and other forms of regular movement can all contribute to physical activity.
For older adults, the type and intensity of exercise should be appropriate to their physical condition.
5. Smoking
Smoking is damaging to blood vessels and is already a major risk factor for cardiovascular disease and stroke.
Its implications for brain health are also significant.
The Lancet Commission’s dementia research has consistently identified smoking as a modifiable risk factor. The 2020 Commission estimated that smoking accounted for a measurable portion of dementia risk, alongside hypertension, obesity, physical inactivity, diabetes and other factors.
The good news is that smoking is one of the clearest risk factors people can change.
Stopping smoking may not erase previous damage, but it can reduce exposure to ongoing cardiovascular and vascular injury.
6. Depression
Perhaps the most complicated factor on the list is depression.
Depression and dementia are not the same condition. Depression does not simply “turn into” dementia.
But researchers have repeatedly observed an association between depression and later cognitive decline.
The relationship may work in several directions. Depression can affect sleep, physical activity, social engagement and concentration. At the same time, early changes associated with neurodegenerative disease may sometimes appear as depression or other psychological symptoms before dementia is diagnosed.
Research in the Czech Republic, for example, found depression among several factors significantly associated with dementia, alongside physical inactivity, diabetes and low educational attainment.
This makes treatment of depression important not only for emotional wellbeing but also as part of maintaining overall health.
Does changing your lifestyle actually reverse dementia?
This is where the headline needs careful interpretation.
Changing these factors does not mean an existing dementia diagnosis can simply be reversed.
There is currently no lifestyle programme proven to reverse Alzheimer’s disease or eliminate dementia once the underlying neurodegenerative disease has developed.
What the research suggests is different: addressing modifiable risk factors may reduce the probability of developing dementia, delay its onset, or slow aspects of cognitive decline in some people.
That distinction is crucial.
A person with high blood pressure who starts exercising and controls their blood pressure has not “cured dementia”. But they may have reduced one of the factors that can contribute to future cognitive problems.
The bigger picture: scientists now identify 14 risk factors
The story becomes even more interesting when we move beyond the six factors.
The 2024 Lancet Commission expanded the list of potentially modifiable dementia risk factors to 14.
They include:
- Lower educational attainment
- Hearing loss
- High LDL cholesterol
- Depression
- Traumatic brain injury
- Physical inactivity
- Diabetes
- Smoking
- Excessive alcohol consumption
- Hypertension
- Obesity
- Social isolation
- Air pollution
- Vision loss
Taken together, the Commission estimated that eliminating these risk factors could theoretically prevent or delay nearly 45% of dementia cases worldwide.
That is a remarkable figure — but it should not be interpreted as saying that 45% of individual people with dementia could have avoided the disease simply by making different lifestyle choices.
These are population-level estimates based on statistical models and assumptions about causality.
The African and Kenyan question
The findings are particularly relevant for African countries such as Kenya, where populations are ageing while non-communicable diseases such as hypertension and diabetes are becoming increasingly important.
Research involving six low- and middle-income countries — China, South Africa, Ghana, India, Russia and Mexico — estimated that approximately 37.6% of the dementia burden could potentially be attributed to ten modifiable risk factors. Interestingly, the estimated proportion varied between countries, ranging from 22.9% to 38.3%.
That variation is a reminder that dementia risk is not identical everywhere.
Education, healthcare access, nutrition, physical activity, smoking, environmental exposures, cardiovascular disease and socioeconomic conditions can all vary substantially between populations.
For Kenya, this raises an important public-health question: could better prevention of hypertension, diabetes, obesity and smoking today translate into fewer cases of dementia decades from now?
The available evidence suggests that it is a question worth taking seriously.
You don’t have to wait until old age
Perhaps the most encouraging message from this research is that brain health is not something people should start thinking about only after memory problems appear.
The Alzheimer’s Association currently recommends several practical approaches that may help reduce dementia risk, including controlling high blood pressure, maintaining a healthy weight, managing blood sugar, quitting smoking, getting adequate sleep, eating a healthy diet, staying physically active and remaining socially engaged.
These recommendations are hardly revolutionary.
They are many of the same things doctors have been recommending for heart health for decades.
The emerging science simply adds another reason to take them seriously.
Protecting the brain may begin with protecting the body
The traditional image of dementia prevention often involves brain-training games, crossword puzzles and memory exercises.
Mental stimulation can certainly be valuable. But the research increasingly paints a much broader picture.
The brain appears to benefit from a healthy body, healthy blood vessels, regular movement, social connection, adequate sleep and good management of chronic diseases.
There is no guarantee that following all these recommendations will prevent dementia. Some people who exercise, eat well and never smoke will still develop Alzheimer’s disease or another form of dementia.
Genetics and ageing remain powerful influences.
But that does not make lifestyle changes pointless.
If modifying several risk factors can delay dementia even for a few years at the population level, the consequences could be enormous — potentially reducing the number of people requiring intensive care while giving older adults more years of independent living.
And perhaps that is the most important message behind the research.
Dementia may not be entirely preventable, but neither is the future of our brains necessarily written in our genes.
This article is for general information and does not replace medical advice. Anyone concerned about memory loss, depression, high blood pressure, diabetes or other dementia risk factors should discuss them with a qualified healthcare professional.
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