What is dementia? Types, symptoms, causes and treatment

There is much we can do alleviate dementia

By the year 2040, there will be 1.7 million people in the UK living with dementia, according to the latest concerning forecasts published in leading medical journal The Lancet.

As a result, many scientists view dementia as one of the leading public health challenges of the 21^st century, due to the toll it places on patients, their families and the healthcare system.

However, experts remain optimistic that our growing understanding of dementia will allow us to increasingly prevent many of these cases, lead to new treatments, and help find better ways of managing dementia once people are diagnosed.

“Right now, the reality for people facing dementia is often years of hardship, stress and isolation,” says James Rowe, professor of cognitive neurology at the University of Cambridge. “But even today, there’s so much more that could be done. If we implemented the best practice knowledge that we have today, we would prevent about 40% of dementia.”

So what is dementia and what are the main causes?

Skip to:

• What is dementia?
• Causes
• Prevention
• Symptoms
• Tests and diagnosis
• Treatment
• New medications
• Living with dementia
• Lifestyle changes

What is dementia?

One of the most common misconceptions is that dementia is a single condition. Instead, neuroscientist Tara Spires-Jones, professor of neurodegeneration at the University of Edinburgh, describes dementia as a set of symptoms that can be caused by many different diseases.

There are thought to be at least 200 different dementias, of which the below five types are some of the most common:

• Alzheimer’s disease
• Vascular dementia
• Frontotemporal dementia
• Lewy body dementia
• Young-onset dementia

Causes

While the underlying disease processes vary considerably from one dementia to another, they share many of the same risk factors that can predispose the brain to damage.

These include:

• Age
• Genetics
• Chronic inflammation

Research has shown that the ageing process is arguably the biggest of all dementia risk factors. For example, the number of people with Alzheimer’s disease, the most common form of dementia, doubles every five years beyond the age of 65. This is thought to be related to several age-related processes.

As we get older, different parts of our brain can atrophy or shrink in size, while our bodies become steadily more inflamed, often as a consequence of many years of unhealthy life choices. This chronic inflammation can progress through the bloodstream into the brain, where it causes damages to neurons and other types of brain cells.

Some people are also more vulnerable to developing a form of dementia due to their genetics. For example, inheriting two copies of a gene variant called Apolipoprotein E4 increases risk of developing the disease by between eight and 12 times compared with someone with no copies of this form of the gene. Likewise, genetics are thought to be behind a third of all cases of frontotemporal dementia.

Paresh Malhotra, a neurology professor at Imperial College London, says that research has linked mutations in genes with toxic protein deposition in the brain regions that are damaged in frontotemporal dementia. “That’s what’s killing the nerve cells in the brain, these abnormal protein deposits,” he says.

Prevention

Risk factors include:

• Smoking
• Depression
• Excessive alcohol consumption
• Physical inactivity
• Type 2 diabetes
• Obesity
• Social isolation

The good news is that many of the risk factors can be taken under control, which will lessen your likelihood of getting dementia.

Quitting smoking is thought to be one of the most powerful strategies for lowering dementia risk, with current smokers found to be 30% more likely to develop some form of dementia. This is due to the damage that smoking can inflict on the heart and blood vessels over time, impacting blood flow to the brain.

Research published in the journal JAMA Neurology, which used data from more than 1.4 million people in Denmark, found that being diagnosed with depression as an adult can double your risk of dementia, possibly because damage that smoking can inflict on the heart and blood vessels over time

Traumatic brain injury, hearing impairment, hypertension and lower levels of education can all also increase dementia risk.

In 2023, newly published data from the Health and Retirement Study, an ongoing study of ageing in the US, found that greater exposure to PM2.5 air pollution was linked to dementia. In particular, pollutants released by agricultural processes and wildfires appeared to drive risk.

Early signs and common symptoms

• Mild forgetfulness
• Difficulty with speech, writing clearly or communicating
• Change in personality

The early stages of different dementias can vary subtly from one disease to another. Spires-Jones says that in the early stages of Alzheimer’s disease, people often experience mild forgetfulness. “It’s things like memory and spatial memory, so where you put things and remembering what happened earlier in the day, where you put the car, that sort of thing,” she says.

However, in frontotemporal dementia, aphasia – a condition that affects the ability of the patient to speak and write clearly, and understand written words – is a common early sign. This is because the disease can damage a particular part of the brain called the temporal lobes. “They are more involved in speech, and they are one of the areas which stop working first,” says Malhotra.

As different dementias progress, many of the symptoms of cognitive decline begin to overlap more and more. “Dementias don’t just affect memory, they change personality, who we are as people in our relationships, how we can communicate, our ability with language,” says Rowe. “These are things that dementias affect, and different dementias do it in different ways to different extents.”

Types

Alzheimer’s disease

Alzheimer’s is characterised by brain changes that lead to the accumulation of certain proteins, most notably amyloid, which clusters into plaques, and tau, which forms tangles. These protein deposits are toxic to the brain and drive both cell death and shrinkage of different brain regions.

Scientists are still trying to understand what triggers these hallmarks of the disease, and there are likely to be multiple causes. In many patients, the progression of Alzheimer’s is thought to be linked to the immune system waning with age, as well as changes in metabolism that affect how the brain processes fats, all of which contribute to neurodegeneration over time.

“There are multiple components to this complex disease, of which amyloid plaques is one,” says Julie Williams, a professor at Cardiff University who studies Alzheimer’s. “But it’s not the whole story.”

Vascular dementia

Having high cholesterol, elevated blood pressure and highly fluctuating blood sugar levels can all place the heart under stress, and over time this has a negative impact on the brain. This can happen through restricted blood flow due to partial or complete blood clots, which has a damaging effect on brain tissue.

“Cardiovascular disease and diabetes are two of the main contributing factors to the vascular changes in the brain that occur relatively late in life,” says Philip Scheltens, professor of neurology and founder of the Alzheimer Centre at Amsterdam University Medical Centres.

Scheltens points out that many dementia patients over the age of 75 will have a mixture of Alzheimer’s and vascular dementia. “Pure vascular dementia in itself is quite rare,” he says. “But the vascular contribution to Alzheimer’s disease is quite prevalent.”

Frontotemporal dementia

Frontotemporal dementia is an umbrella term for a larger group of neurodegenerative diseases that all impact the frontal areas of the brain. While patients ultimately struggle with all aspects of cognition, the earliest signs are problems with speech, motivation as well as a loss of inhibition, all facets of behaviour that are controlled by the frontal brain regions.

“Being rude to strangers can be early signs which are sometimes missed,” says Malhotra. “People can also have issues with vocabulary, not being able to find the right word or speak as fluently as before.”

Just like Alzheimer’s, frontotemporal dementia is linked to abnormal protein deposition in the frontal brain areas. “The more we understand about that, the more research that is underway to develop new treatments which can reduce the amount of protein that’s deposited, or perhaps even develop drugs that might be able to clear it,” says Malhotra.

Lewy body dementia

This form of dementia often occurs in combination with Alzheimer’s, with Scheltens estimating that half of all Lewy body dementia patients also have brain changes associated with Alzheimer’s.

It is caused by small deposits of a protein called alpha-synuclein, which is also implicated in Parkinson’s disease. Over time this damages nerve cells in the brain, and many patients also develop tremors or stiffness.

“Typically these patients have relatively spared memory function, but they cannot plan, organise or think ahead,” says Scheltens. “They have orientation issues so they forget where they park their car, they don’t know where they were, and they often have visual hallucinations.”

In recent years, advances in brain imaging are making it easier for neurologists to pinpoint patients with Lewy body dementia, which could lead to more clinical trials for the condition.

Young-onset dementia

Young-onset dementias occur in people under the age of 65, sometimes even in their 30s, although this is extremely rare. However, in total, there are more than 70,000 people in the UK currently living with some form of young-onset dementia.

While these diseases are also related to abnormal protein deposition, scientists are still trying to understand what makes some individuals vulnerable to the disease at a much earlier stage in life.

“Some of these cases happen where the disease runs in the family and there’s a genetic driver,” says Scheltens. “But that’s still only 1 per cent of all cases. The other 99 per cent are what we call sporadic, and we currently know little about what causes them.”

Dementia tests and diagnosis 

There is currently no single test for dementia. Instead, a diagnosis is typically reached via a combination of cognitive assessments, initially from a GP and then at a specialist memory clinic, which determine short and long term memory, awareness, language and communication, and attention span.

In the coming years, such assessments could be combined with blood tests to help confirm the diagnosis of a particular dementia. The first such test is likely to be for Alzheimer’s disease, and could be used to help recruit patients for clinical trials of new treatments, as well as determining eligibility for new breakthrough medications.

“In research settings now, we’ve got blood tests that are able to predict whether somebody has the amyloid protein within the brain with more than 90 per cent accuracy,” says Professor Jonathan Schott of the University College London Institute of Neurology.

Treatment

At the moment, the treatments available on the NHS tend to focus on managing some of the symptoms of the disease.

For Alzheimer’s

People with early to mid-stage Alzheimer’s can be prescribed drugs such as donepezil, galantamine and rivastigmine, which increase levels of a brain chemical called acetylcholine to help nerve cells communicate with each other.

For vascular dementia

People diagnosed with vascular dementia can be prescribed medicines to lower cholesterol or blood pressure, while Malhotra says that speech and language therapy and even antidepressants can help with the symptoms of frontotemporal dementia. “We do prescribe them quite often,” he says. “But there’s no treatment that slows down the shrinking of the brain, per se.”

New medications

In 2022 and 2023, clinical trials of medications called donanemab and lecanemab, therapies that work by removing amyloid from the brain, gave new hope to people living with Alzheimer’s after the results showed that they can slow the rate of cognitive decline by between 27 and 35 percent.

While neither treatment is yet available on the NHS, it is hoped that these drugs will be the first of many therapies that can alter the disease course of various dementias.

Schott predicts that drugs like donanemab and lecanemab may ultimately be able to offer the most benefit in people who are yet to develop symptoms but are on a path towards developing Alzheimer’s.

“We know that this period of time extends for a decade, or more, before symptoms arise,” he says. “So the question is, might it be possible to identify people who are on that pathway, who are at risk, and treat them? That may well be the direction of travel in the years to come.”

Living with dementia: new technologies and digital tools

While a diagnosis of dementia may be devastating for people and their families, experts are keen to emphasise that people can live well with the disease for many years, something becoming more plausible with the emergence of new technologies.

Emma Hewat, head of dementia at KYN, a new innovative care home based in Bickley, south-east London, says that families can easily implement various assistive aids in their homes, such as large button phones and dementia-friendly radios with simple controls.

Professor James Ohene-Djan of Goldsmiths, University of London, has developed a new digital tool named MiCode which aims to mitigate the risks associated with wandering, something affecting 60 per cent of dementia patients.

The tool embeds a personalised QR code containing the wearer’s name, emergency contacts, medical information and other essential data into a bracelet, keyring, card or pendant.

Lifestyle changes 

Hewat says that simple lifestyle steps such as a regular sleeping pattern, a balanced diet, and continuing to go out and meet other people can help people live well with dementia for as long as possible.

“It’s useful to think about the trajectory of dementia in three stages: early, middle and late,” she says. “In the middle stages, more support is often required, as people’s abilities start to decline, affecting their day-to-day lives. However, staying busy and keeping active can help. Everyone experiences dementia differently, and it can be difficult to predict when someone will move from one stage to another or how long each stage takes. Looking to the future can seem daunting, but there is plenty you and your families can do to live well with dementia.”

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