What is dementia?

Dementia is an umbrella term used to describe a group of symptoms that affect how well our brains work.

Dementia can affect anyone, and as people get older the chances of developing dementia increase.

The most common form of dementia is Alzheimer’s disease – which around two-thirds of people with dementia have.

The symptoms each person experiences depends on the parts of the brain that are affected. However, the most common dementia symptoms include changes in memory, thinking, behaviour, personality and emotions. These changes affect a person’s ability to perform everyday tasks and interfere with their everyday lives.

Dementia is progressive, which means that for most people the changes gradually spread through the brain and lead to the symptoms getting worse. Dementia is different for everyone – what people experience, and how quickly they are affected is unique to them. What they can do, remember and understand may change from day to day.

Find information on supporting someone affected by dementia

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 Forms of dementia

No one single factor has been determined as the cause of dementia. It is likely that a combination of factors, including age, genetic inheritance and environmental factors, are responsible. Some of the most common forms are:

Alzheimer's disease

This is the most common form of dementia - around two-thirds of people with dementia have Alzheimer's disease. Although we are still learning about the causes, there are typical changes seen in the brain - shrinkage and a build-up of abnormal proteins (plaques and tangles).

Alzheimer’s disease is progressive, starting as forgetfulness and mild confusion, progressing to memory loss, disorientation and changes in personality and behaviour. The specific symptoms can vary, depending on the part of the brain that is affected.

Vascular dementia

This is the second most common form of dementia. This group of conditions is caused by poor blood supply to the brain as a result of a stroke or several mini-strokes, or by the slow accumulation of blood vessel disease in the brain. Vascular dementia symptoms can begin suddenly after a stroke or gradually as disease in the blood vessels worsen. Some people will have both vascular dementia and Alzheimer’s disease.

Lewy Body disease

This condition is characterised by the presence of ‘Lewy Bodies’, which are abnormal clumps of protein in the brain. These cause changes in movement, thinking, behaviour and alertness. People with Lewy Body disease can fluctuate between almost normal functioning and severe confusion within short periods, and may also have hallucinations, seeing things that aren't really there.

Frontotemporal Dementia

Fronto-temporal dementia is a group of conditions which affect the frontal and/or temporal lobes of the brain. If a person has affected frontal lobes they will have increasing difficulty with motivation, planning and organising, controlling emotions and maintaining socially appropriate behaviour. If temporal lobes are affected the person will have difficulty with speaking and/or understanding language. Symptoms often begin in a person's 50s or 60s.

 Early warning signs

The early signs and symptoms of dementia can be subtle and hard to recognise. Many conditions, such as stroke, depression and infections, as well as normal ageing, can cause dementia-like symptoms. It’s important not to assume any changes are due to dementia.

It’s also very important to see your doctor as soon as you have any concerns. If your symptoms are caused by a treatable condition, you can then be diagnosed and treated.

If your symptoms are caused by dementia, an early diagnosis means you and your family/whānau have early access to support, information, and any appropriate treatment. You also have time to plan for your future.

10 warning signs of dementia

1. Recent memory loss that affects daily life

It’s normal to forget meetings, names or telephone numbers occasionally and then remember them later.
A person with dementia might have trouble remembering recent events.

2. Difficulty performing regular tasks

It’s normal to make a wrong turn occasionally while driving.
Someone with dementia might have regular difficulty driving a familiar route.

3. Problems with language

Many people have trouble finding the right words sometimes.
But someone with dementia might have difficulty following, or initiating a conversation.

4. Disorientation of time and place

It is normal to occasionally forget what day it is or where you are going
A person with dementia may be confused about the time of day, and what is appropriate for that time.

5. Decreased or poor judgment

Making a bad decision once in a while is normal.  
A person with dementia might make bad decisions more frequently and start paying less attention to their physical appearance.

6. Problems with abstract thinking

It’s normal to have difficulty balancing a budget.
A person with dementia might completely forget what the numbers are and what needs to be done with them.

7. Misplacing things

Anyone can misplace their wallet or keys.
A person with dementia might repeatedly put things in inappropriate places.

8. Changes in mood and behaviour

Everyone becomes sad or moody from time to time.
A person with dementia can have rapid mood swings, from calm to tears to anger, for no apparent reason.

9. Changes in personality

People's personalities can change a little with age
A person with dementia might have problems in social situations they have previously been comfortable with.

10. Loss of initiative

It is normal for people to tire of housework, business activities or social obligations.
A person with dementia may no longer initiate things that they once enjoyed. 

Find out about the 10 Warning Signs of Dementia


 Memory lapses vs memory loss

It’s important to understand what is dementia and what isn’t. We all forget things from time to time and often complain our memory isn’t what it used to be, but this doesn’t necessarily mean we’re getting dementia.

Memory loss from dementia is quite different to occasionally forgetting things. Memory loss from dementia isn’t just occasional and it keeps getting worse. It may affect a person’s ability to work and carry out everyday tasks, which may eventually include how to dress, bathe, walk or recognise family members.

It helps to know what are probably just normal changes in the brain as we age and what may be linked to dementia. If you’re worried about your memory, go and see your GP, because depression, stress, the side effects of some medication, and other treatable conditions might be behind any memory loss. 


  • An older person’s memories may sometimes be vague.
  • A person with dementia may forget all or part of an event.

Words or names

  • An older person might sometimes forget or have words or names that are on the ‘tip of the tongue’
  • Someone with dementia may progressively forget words or names, or use the wrong word for something.

Stories on TV, in movies or books

  • An older person is able to follow storylines.
  • People with dementia may become increasingly unable to follow storylines.

Written and verbal directions

  • An older person is able to follow directions.
  • People with dementia can become increasingly unable to follow directions.

Knowledge and information

  • Although recall may be slower, an older person can essentially remember information.
  • Over time, a person with dementia can lose known information such as historical or political events.

Everyday tasks such as dressing and cooking

  • Unless there’s a physical reason, an older person can perform these tasks.
  • A person with dementia can progressively lose the ability to do these everyday tasks.

 Family links with dementia

Some forms of dementia can have family links, which means some forms of dementia may be inheritable. About a third of people with Alzheimer’s disease have a close relative (parent, brother or sister) who has, or has had, this condition.

This does not necessarily mean it is inherited and for many people there’s no family history.

If you have any concerns about a family history of dementia, please see your GP. Remember, there are many other treatable reasons for memory lapses, confusion and forgetfulness.

 The impact of dementia in NZ

Dementia is one of New Zealand’s most significant and growing healthcare challenges. Almost 70,000 Kiwis have dementia & that number is expected to almost triple by 2050. 

Dementia also has a significant impact on the family/whanāu and friends of people with the condition. A survey we conducted in 2017 indicated that 4 out of every 5 New Zealanders knows or has known someone with dementia.

The total financial cost of dementia on the health system in 2011 was estimated as $954.8 million.

Informally, the value of those who were fully or partially removed from the workforce to care for someone with dementia was estimated at $37.7 million.

If you are worried that you or someone you know is showing signs of dementia, see your GP for a full assessment. For information and support, contact your local Alzheimers organisation.