Dementia is the word we use when the brain gets an illness that damages it & changes how it works. It means the brain is unwell in a way that changes how you think, remember, interact, move to such an extent that it affects your ability to live your daily life.
What is dementia can be complicated to understand, but that’s the simplest way I’ve found to explain it, and after caring for my mum for over a decade, I’ve heard a lot of explanations.
Some are too medical, some too vague. But this one helped me understand better, it’s an illness that causing damage to the brain, plain and simple.
It gets more complicated when you try to understand the different types of illnesses that cause dementia.
So this article is a simple answer to the question, what is dementia, from someone who’s cared through it.
Dementia Isn’t One Disease
There’s a lot of confusion over the term dementia as it gets mixed up with the diseases that cause dementia.
A lot of people think Alzheimer’s and Dementia for example are the same thing, they’re not. But more on that later.
Dementia isn’t one disease. It’s a word we use to describe a group of symptoms that happen when the brain is damaged by disease, just like “cancer” isn’t one illness, but a word that covers lots of different types.
When someone says they have cancer, we usually ask what kind? Is it breast cancer? Lung cancer? Skin cancer? Each type is different, even though they’re all called cancer.
It’s the same with dementia. Dementia is the umbrella term, (you’ll hear that word a lot!) – the overall word for problems with memory, thinking, and daily life caused by brain disease.
Alzheimer’s disease is the most common cause of dementia, but it’s not the same thing as dementia.
So when we say someone has dementia, it’s a bit like saying someone has cancer. We know something serious is going on but we need to know which type it is, because that helps us understand what symptoms to expect and how best to support them.
What Causes Dementia?
So dementia is a word we use for a group of symptoms that happen when the brain is damaged by disease. Different diseases affect different parts of the brain, which is why one person’s experience can be completely different to another’s.
Here are the main causes
- Alzheimer’s disease – The most common, accounting for 60–80% of cases³.
- Vascular dementia – Caused by reduced blood flow to the brain, often after strokes⁴.
- Lewy body dementia – Involves abnormal proteins that also affect movement, sleep, and thinking⁵.
- Frontotemporal dementia – Often affects younger people first and changes personality or language before memory⁶ .
- Mixed dementia – When more than one type is present, often Alzheimer’s plus vascular dementia⁷.
These are the most common, but there are so many types of rare dementia, there are over 100 types of dementia. The common thread is that they all change how the brain works by the disease that affected it, and that changes your loved ones daily life.
How Common Is Dementia?
There are more people living with dementia than most people realise. In the UK, over 944,000 people are living with dementia today. That’s about one in eleven people over the age of 65¹.
Globally, around 57 million people are affected, with nearly 10 million new cases diagnosed every year².
- In the UK, over 944,000 people are living with dementia today — that’s about 1 in 11 people over the age of 65¹.
- Globally, around 57 million people are affected, with nearly 10 million new cases diagnosed every year².
- It’s the leading cause of death in England and Wales, and yet thousands remain undiagnosed or misdiagnosed, particularly with less well-known types like Lewy body or frontotemporal dementia⁸.
Younger people can develop it too. It’s not just something that happens later in life. It’s called young-onset dementia when symptoms appear before age 65. I’ve met people in support groups in their 40s and 50s facing it.
When dementia shows up in someone’s life, it doesn’t mean they’ve stopped being themselves. But it does mean the way their brain works is starting to shift from damage, and that shift brings changes, often slow at first, but noticeable. It affects memory, language, decision-making, physicality, mood or behaviour and more depending on the type of illness causing the dementia.
It’s not part of just getting older. Remember, it’s a medical condition, caused by disease in the brain¹.
What It Looks Like in Real Life
In the beginning, the changes can be subtle. With my mum, I noticed she’d stop halfway through making a cup of tea, unsure what came next or getting lost on the way home from the supermarket. Or she’d repeat herself without realising, not once or twice, but five or six times in the space of a few minutes.
In hindsight, you see more, like the falls, like not being sure of things and like the way she tried to cover her mistakes. That’s just one caregiver’s example, but it affects individuals differently.
It not just memory lapses, there can be so many signs that your loved ones brain is processing information differently.
People with dementia might:
- Seem more anxious, withdrawn, or suspicious
- Struggle to find the right word
- Get confused about time or place
- Forget familiar faces or mix up relationships
- Have trouble following instructions
- Have problems with their gait, walking or bumping into things
These symptoms don’t happen all at once. And they often progress slowly, although the speed varies for each person.
That’s important to realise, everyone is different, and how it affects them.
You don’t go around thinking everyone with cancer is the same, so the same applies to dementia, everyone is unique.
As Professor Tom Kitwood said “If you have met one person with dementia, you have met one person with dementia“.
Why It’s Important to Get a Diagnosis
Getting a diagnosis doesn’t fix everything, but it gives you a starting point. It helps you understand what’s happening and plan for what’s ahead.
In England, despite a record number of diagnoses, around 240,000 people may still be living with undiagnosed dementia⁸. That means many families are trying to cope without the right information or support.
When we finally got the diagnosis for my mum, it didn’t feel like a loss. It felt like a relief that it wasn’t something worse. We knew what it was and that helped us with getting support and to have choices.
Can Dementia Be Prevented or Slowed?
There’s no cure yet, but some lifestyle changes may reduce risk or slow progression like:
Staying mentally active
Keeping physically active
Eating a balanced diet (like the Mediterranean or MIND diet)
Treating high blood pressure and diabetes
Avoiding smoking and excessive drinking
Getting good sleep⁹
Some medications like donepezil or rivastigmine can help with symptoms in Alzheimer’s and Lewy body dementia¹⁰. They don’t stop the disease, but they can give people more clarity and independence for a time.
Newer drugs have been approved for Alzheimer’s disease namely Donanemab and Lecanemab for slowing down the effects of the disease, and there are more drugs being developed.
Living With Dementia, Not Just Managing It
Dementia doesn’t mean the end of connection or joy. It means adjusting, simplifying, and finding new ways to relate. Once you hear the word dementia you focus on the end stage, but as the author Wendy Mitchell diagnosed with young onset dementia at 58 once said, dementia has a beginning, middle and end. But before the end, there’s so much life to live in between.
For me and my mum, the best days were the ones where we kept things simple and normal. A walk, a cup of tea, folding laundry together, or singing along to music from her youth.
I didn’t let the disease define her and I had to learn to change my perceptions, it was her life to live as she pleased we just learnt new ways to communicate, live and help her as her Alzheimer’s progressed.
It’s not just about managing dementia. It’s about meeting your loved one where they are, even if that place changes from day to day.
In Summary
Dementia means the brain is unwell in a way that changes how someone thinks, remembers, and affects their day to day living. It shows up in different ways depending on the cause, and it affects more than just memory. It touches every part of daily life. It’s not an old person’s disease. You can reduce your risk of getting dementia through lifestyle changes. Millions of people are living with dementia right now.
Understanding what is dementia helps. It brings clarity, compassion, and a bit more control during a time when so much feels uncertain.
If someone you love has dementia, or you’re going through this yourself, know this. You’re not alone, and there are ways to make life easier, gentler, and more supported.
Footnotes
¹ NHS – About dementia
² WHO – Dementia
³ Alzheimer’s Society – Alzheimer’s disease
⁴ Alzheimer’s Society – Vascular dementia
⁵ Alzheimer’s Society – Lewy body dementia
⁶ Alzheimer’s Society – Frontotemporal dementia
⁷ Alzheimer’s Society – Mixed dementia
⁸ The Times – Dementia diagnoses
⁹ Alzheimer’s Society – Risk reduction
¹⁰ NHS – Dementia treatment
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