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Disclaimer: This article is for informational purposes only and does not constitute medical advice. If you are concerned about memory problems or have received a dementia diagnosis, please speak with your GP or a qualified healthcare professional.
If someone you love has recently been diagnosed with dementia, or you are worried about changes you have noticed, it is natural to want to understand what can cause dementia and why it happens.
Dementia is not a single disease. It is a term used to describe a group of symptoms, including memory loss, confusion, and changes in behaviour, that occur when brain cells are damaged and lose their ability to communicate effectively. Many different conditions can cause dementia, not just Alzheimer’s disease, and understanding the specific cause can make a real difference in how it is managed and what support is available.
In this guide, we explain the most common causes of dementia, the other conditions linked to it, the risk factors that may play a role, and what you can do if you are concerned.
Dementia is caused by damage to brain cells, which disrupts the way those cells communicate with one another. As different areas of the brain slowly lose cells, they begin to shrink—a process known as brain atrophy. The symptoms someone with dementia experiences depend on which areas of the brain are affected.
Some causes of dementia are things we cannot change, including age, sex, and genetic makeup. Others are influenced by lifestyle and health conditions that, with the right support, may be possible to address. In most cases, dementia does not result from a single cause, but a combination of factors acting together over many years.
Causes You Cannot Change | Risk Factors You May Be Able To Reduce |
Age | High blood pressure |
Sex | Smoking |
Genetics and family history | Excessive alcohol intake |
Ethnicity | Physical inactivity |
Down syndrome | Untreated hearing loss |
Poor sleep | |
Social isolation |
Dementia has many causes. Below are the most common diseases and conditions responsible, along with what makes each one distinct.
Alzheimer’s disease is the most common cause of dementia, accounting for around 60-70% of all diagnoses. It is caused by an abnormal build-up of two proteins in the brain. Amyloid clumps together to form plaques around brain cells, while tau forms tangled fibres inside them. These deposits damage and eventually kill brain cells, beginning in the hippocampus—the region responsible for forming new memories—which is why memory loss is typically one of the first signs.
While the exact triggers are not fully understood, age, genetic factors (particularly the APOE-e4 gene), and lifestyle all appear to play a role. A small percentage of cases are linked to inherited gene mutations passed down through families.
For more on how we support people living with this condition, visit our Alzheimer’s care service page.
Vascular dementia is the second most common type, caused by reduced blood flow to the brain. When brain cells are starved of the oxygen and nutrients carried in the blood, they become damaged and die. This can happen as a result of a single stroke, a series of mini strokes (known as transient ischaemic attacks, or TIAs), or more gradual damage to the small blood vessels in the brain due to conditions such as high blood pressure, high cholesterol, and diabetes.
Unlike Alzheimer’s, where memory loss tends to be the first obvious symptom, vascular dementia often presents first with difficulties in problem-solving, slowed thinking, and poor concentration. It is strongly linked to cardiovascular health, making it one of the most potentially preventable forms of dementia.
Did you know: Having a stroke more than doubles a person’s risk of developing dementia. However, not everyone who has a stroke will go on to develop the condition. Early treatment and management of cardiovascular risk factors can make a significant difference.
Dementia with Lewy bodies (DLB) is the third most common type and is caused by abnormal deposits of a protein called alpha-synuclein, known as Lewy bodies, building up inside brain cells. These deposits disrupt normal brain cell function and eventually lead to cell death.
DLB shares features with both Alzheimer’s disease and Parkinson’s disease. Distinctive symptoms include vivid visual hallucinations, significant fluctuations in alertness and concentration, and movement difficulties similar to those seen in Parkinson’s. Sleep disturbances—particularly acting out dreams—are also common.
Frontotemporal dementia (FTD) is caused by damage to the frontal and temporal lobes of the brain—the regions responsible for personality, behaviour, and language. Unlike Alzheimer’s, memory is often relatively preserved in the early stages; instead, the first signs may be significant changes in personality, socially inappropriate behaviour, loss of empathy, or difficulties with speech and language.
FTD is more likely than other types to run in families, and it is one of the more common causes of young-onset dementia.
Mixed dementia occurs when a person has more than one type of dementia at the same time—most commonly, Alzheimer’s disease alongside vascular dementia. It is more common than previously thought, particularly in people aged 80 and over. Because the causes overlap, mixed dementia can be difficult to diagnose, and symptoms tend to reflect whichever type is most dominant.
Type | Primary cause | Key distinguishing features | How common |
Alzheimer’s disease | Amyloid plaques and tau tangles in the brain | Memory loss (especially recent events) is often the first sign | Most common |
Vascular dementia | Reduced blood flow to the brain | Problem-solving difficulties; slowed thinking; may appear suddenly after a stroke | 2nd most common |
Dementia with Lewy bodies | Lewy body protein deposits in brain cells | Visual hallucinations; fluctuating alertness; movement difficulties | 3rd most common |
Frontotemporal dementia | Damage to the frontal and temporal lobes | Personality and behaviour changes before memory loss; more common in under-65s | Less common |
Mixed dementia | A combination of two or more types | Overlapping and variable symptoms; more common in the over-80s | Underdiagnosed |
Beyond Alzheimer’s and vascular dementia, many people ask what other conditions can cause dementia. Several diseases can lead to dementia symptoms or significantly increase the risk of developing them.
Parkinson’s disease is caused by loss of nerve cells in the brain, primarily affecting movement and coordination. Those with Parkinson’s are 6 times more likely to develop dementia, usually in the later stages of the condition.
There are two closely related forms: Parkinson’s disease dementia and dementia with Lewy bodies. Both involve Lewy body protein deposits, but they develop in a different order and progress differently.
Huntington’s disease is a genetic disorder caused by a faulty inherited gene that leads to a harmful protein building up and progressively damaging nerve cells in the brain, particularly in areas responsible for movement, learning, and emotion. It typically affects people in their 30s or 40s. Some people with Huntington’s disease go on to develop dementia in the later stages.
Creutzfeldt-Jakob disease is a rare but rapidly progressing brain condition caused by abnormally shaped proteins called prions, which damage brain tissue. Early symptoms can include memory problems, mood changes, and confusion, but CJD progresses far more quickly, typically over weeks to months rather than years. It is not passed from person to person in ordinary contact.
Normal pressure hydrocephalus is caused by a build-up of cerebrospinal fluid in the brain’s ventricles, putting pressure on brain tissue. It presents with a classic trio of symptoms: difficulty walking (often described as a shuffling gait), memory problems, and loss of bladder control.
Importantly, NPH is one of the few conditions that can cause dementia-like symptoms that may be reversible with treatment—specifically, surgical drainage of the excess fluid. This is one of the key reasons why a thorough medical assessment matters so much when cognitive symptoms first appear.
Certain infections have been linked to an increased risk of dementia or can cause dementia-like symptoms. These include some viral infections such as HIV and herpes, bacterial infections such as Lyme disease and syphilis, and serious brain infections such as encephalitis or meningitis. The risk from minor infections is very low; it is prolonged, severe, or recurring infections affecting the brain that are most relevant. Research into the links between infections and dementia is ongoing.
A risk factor is something that increases the likelihood of developing a condition; it does not mean it is inevitable.
Some risk factors for dementia are fixed and cannot be changed. Others are modifiable, meaning some steps may help reduce them.
Research suggests that up to 40% of dementia cases may be preventable or delayable through lifestyle and health changes, according to the 2024 Lancet Commission on dementia prevention. Addressing the following risk factors is not a guarantee, but it may make a meaningful difference:
There is no certain way to prevent dementia. However, there is credible and growing evidence that reducing modifiable risk factors can delay its onset or reduce its severity.
The lifestyle changes backed by the strongest evidence are:
It is also worth noting that some conditions that cause dementia-like symptoms—including nutritional deficiencies, thyroid problems, medication side effects, and normal pressure hydrocephalus—are potentially reversible with treatment. Early, accurate diagnosis can therefore open doors that might otherwise seem closed.
Understanding what can cause dementia is one part of the picture, but recognising the early signs is equally important. Symptoms vary depending on the type of dementia, but common early warning signs include:
These symptoms do not always mean dementia is present, and other conditions can cause similar changes. That is precisely why speaking to a GP early matters.
If you or someone you care for has been experiencing persistent memory problems, increased confusion, changes in personality or behaviour, or difficulties with language and reasoning, it is important to speak to a GP. You do not need to wait until things become severe; early assessment is always better.
A GP can arrange cognitive assessments, blood tests, and, where appropriate, referrals to a memory clinic for specialist assessment. A memory clinic assessment typically involves cognitive testing, a review of medical history, and, in some cases, brain scans. Knowing the cause of dementia symptoms matters: it opens access to the right treatments, appropriate care planning, and specialist support that fits the specific type.
Some things worth knowing before a GP appointment:
A diagnosis of dementia is not the end of the road. Many people go on to live well after a dementia diagnosis, particularly with the right care around them. Specialist dementia care—whether in the home or through supported living— can make an enormous difference to quality of life for both the person living with dementia and the family around them.
At Mountbatton Care, our specialist team provides personalised dementia care and Alzheimer’s care across Liverpool, Southport, Crosby, and Formby. We work closely with families to build bespoke care plans that support independence, dignity, and well-being at home.
Alzheimer’s disease is the most common cause of dementia, accounting for around 60 to 70 per cent of diagnoses. It is caused by an abnormal build-up of amyloid plaques and tau tangles in the brain, which damage and eventually kill brain cells, beginning in the memory centres. Vascular dementia—caused by reduced blood flow to the brain— is the second most common type.
Yes. A stroke—or a series of mini strokes (transient ischaemic attacks, or TIAs)—can cause vascular dementia by cutting off blood supply to parts of the brain. Having a stroke more than doubles a person’s risk of developing dementia. However, not everyone who has a stroke will go on to develop the condition, and managing the underlying risk factors (blood pressure, cholesterol, diabetes) is important in reducing that risk.
For most people, dementia is not directly inherited. Genetics can increase risk, but only a small number of cases—such as some forms of frontotemporal dementia, Huntington’s disease, and rare types of early-onset Alzheimer’s—are caused by specific inherited gene mutations. Having a parent or sibling with dementia increases your risk, but it does not mean you will definitely develop it. If you are concerned about family history, your GP can discuss whether genetic counselling may be appropriate.
Yes, many conditions can cause dementia. These include vascular dementia, Lewy body dementia, frontotemporal dementia, Parkinson’s disease dementia, and Huntington’s disease, among others. Mixed dementia is also more common than previously understood, particularly in people over 80. Getting an accurate diagnosis of the specific type matters because management and care approaches vary.
Some conditions can cause dementia-like symptoms that may improve with treatment. These include normal pressure hydrocephalus (where surgical drainage of fluid can sometimes reverse symptoms), nutritional deficiencies such as low vitamin B12 or folate, thyroid problems, certain medication interactions or side effects, and some infections. This is one of the key reasons why a thorough medical assessment is so important.
While most people diagnosed with dementia are over 65, dementia can occur at any age. Young-onset dementia affects over 70,000 people in the UK. It can occur in people in their 40s and 50s, and in some cases even younger. Frontotemporal dementia and Huntington’s disease are among the more common causes in younger people.
There is strong evidence that regularly drinking more than 14 units of alcohol per week increases the risk of dementia. Heavy and long-term alcohol use can also cause alcohol-related brain damage (ARBD), which produces dementia-like symptoms and is sometimes classified separately from other types of dementia. Alcohol-related cognitive impairment is considered one of the more preventable forms. Reducing alcohol intake to within recommended limits is one of the most impactful lifestyle changes a person can make in terms of brain health.
The first step is to make an appointment with your GP or to accompany your loved one to see their GP. Write down the specific changes you have noticed — what they are, when they started, and how they have progressed — before the appointment. The GP can arrange initial cognitive assessments and, if appropriate, refer to a specialist memory clinic. Early assessment is important because some causes of cognitive symptoms are treatable, and an early diagnosis opens access to support, care planning, and treatment sooner. You can also contact our team at Mountbatton Care for guidance on care options.
Whether you’re looking for support for yourself or a loved one, we’re here to help.