The Different Types of Dementia
In the previous article we saw that dementia is not a disease but a term used to describe a collection of symptoms that occur when the brain is being damaged by disease. Memory loss, confusion, language difficulties, changes in judgement, and increasing problems managing everyday life can all be part of dementia, but the word itself does not tell us what is causing those changes, it simply describes the result.
That distinction matters because different diseases damage the brain in different ways. Two people may both be diagnosed with dementia yet have very different symptoms, very different patterns of decline, and very different experiences of daily life. One person may struggle mainly with memory while another experiences changes in behaviour, movement, or language long before memory becomes a major issue. The reason for those differences often lies in the particular disease affecting the brain.
Alzheimer’s disease
Alzheimer’s disease is the most common cause of dementia and accounts for the majority of cases. It is caused by abnormal proteins that accumulate and form deposits or clumps in the brain, interfering with communication between brain cells. Over time those cells become damaged and begin to die. In most people the disease starts in areas involved in forming new memories, which is why memory problems are often one of the earliest signs.
A person with Alzheimer’s disease may repeatedly ask the same question because the brain is no longer reliably storing the answer. They may forget recent conversations, misplace objects in unusual places, or struggle to remember events that happened earlier in the day. What often surprises families, however, is that older memories can remain remarkably clear for a long time. A person may not remember what they had for breakfast but still speak vividly about their childhood, wedding day, or early working life. This is not selective memory or stubbornness; it reflects the parts of the brain being affected first.
As Alzheimer’s disease progresses, it gradually spreads into other areas of the brain. Language, reasoning, judgement, orientation, and eventually physical coordination can all become affected. It is usually a slow-moving disease and many people live with it for years, passing through a long middle stage where they require increasing support while still remaining socially and emotionally present in important ways.
Vascular dementia
Vascular dementia is the second most common type and develops for an entirely different reason. Instead of abnormal proteins damaging brain cells, the problem involves reduced blood supply to parts of the brain. Brain tissue requires a constant flow of oxygen-rich blood to survive, and when that supply is interrupted by strokes, small vessel disease, or other vascular problems, areas of the brain become damaged.
Because strokes and blood vessel problems can affect many different parts of the brain, vascular dementia often produces a broader and less predictable pattern of symptoms. Memory may not be the primary issue at all and many people instead experience slowed thinking, difficulty planning tasks, poor concentration, or problems organising information. A person may understand exactly what needs to be done yet struggle to mentally sequence the steps involved.
Vascular dementia also tends to progress differently from Alzheimer’s disease. Rather than a slow steady decline, it often progresses in stages. A person may remain relatively stable for a period of time and then experience a noticeable drop in function following another stroke or vascular event. Physical symptoms are also more common earlier in the illness because the areas controlling movement and balance are frequently affected. Weakness on one side, an unsteady gait, slower walking, or increased falls can all appear relatively early.
Lewy body dementia
Lewy body dementia is less widely known but is thought to account for around ten to fifteen percent of dementia cases. It involves abnormal protein deposits called Lewy bodies building up within brain cells and interfering with the brain’s ability to process information properly. The condition shares some similarities with Parkinson’s disease because the same types of protein deposits are involved.
One of the most distinctive features of Lewy body dementia is fluctuation. A person’s alertness and thinking can vary dramatically even within the same day. They may appear relatively clear and engaged in the morning yet become extremely confused, withdrawn, or difficult to communicate with later in the afternoon. Families often find this unpredictability confusing because the person can seem almost like two different people at different times.
Visual hallucinations are also particularly common in Lewy body dementia. A person may see animals, children, strangers, or objects that are not actually there, often describing them in vivid detail and fully believing they are real. In addition, many people develop physical symptoms similar to Parkinson’s disease, including stiff muscles, slower movement, a shuffling walk, tremors, and frequent falls.
Frontotemporal dementia
Frontotemporal dementia differs quite noticeably from the other major forms because memory may remain relatively intact during the early stages. Instead, the disease targets the frontal and temporal areas of the brain, which are heavily involved in personality, behaviour, judgement, impulse control, and language.
The changes families notice are often behavioural before they are cognitive. A person who was previously thoughtful and reserved may become impulsive, socially inappropriate, unusually blunt, or emotionally withdrawn. Someone else may begin making reckless financial decisions, lose empathy for others, or behave in ways that seem completely out of character. Because memory can initially remain quite good, these changes are sometimes mistaken for depression, stress, relationship problems, or personality issues rather than dementia.
Some forms of frontotemporal dementia mainly affect language rather than behaviour. A person may increasingly struggle to find words, understand conversation, or communicate clearly despite otherwise appearing physically well. Frontotemporal dementia also tends to affect younger people more often than other forms of dementia, sometimes appearing in a person’s fifties or early sixties while they are still working and supporting a family.
Mixed dementia
It is also important to understand that some people have more than one type of dementia at the same time. This is known as mixed dementia and becomes increasingly common with age. A person may have both Alzheimer’s disease and vascular damage occurring together, creating a combination of symptoms that does not fit neatly into one pattern. This is one reason dementia can sometimes look different from what families expect after reading a textbook description.
Although the different types of dementia have their own patterns and challenges, they all share one thing in common: they involve diseases damaging the brain over time. The symptoms we see on the outside reflect physical changes taking place within the brain itself. Understanding which disease is involved does not solve every problem, but it often helps families make better sense of what they are seeing and respond in ways that are more supportive, realistic, and informed.
In the end, understanding the different types of dementia is not really about memorising medical labels. It is about recognising that dementia is not one single experience. The person living with it is responding to the particular areas of the brain being affected and the particular disease causing the damage. The more clearly we understand that, the easier it becomes to replace confusion and frustration with patience, understanding, and more realistic expectations.
Further Support
If you are caring for somebody living with dementia and would like more practical guidance on day-to-day care, communication, behaviour changes, routines, safety, and the later stages of the illness, you will find The Dementia Carer’s Guide helpful.
About the author: Michael Willers writes practical plain-English resources for dementia carers and families through Bright Mind Books.