What is dementia?

Dementia occurs as a result of physical changes in the structure of the brain. These changes can affect memory, thinking, behaviour, personality and emotion. Because dementia is a progressive syndrome, symptoms will gradually worsen. The most common form of dementia is Alzheimer's disease, although there are several other forms. No single factor has been identified as a cause for dementia or Alzheimer's disease. It is likely that a combination of factors, including age, genetic inheritance and environment are responsible.

There are around 50,000 people with dementia in New Zealand and for each of these people, there is a whole network of others around them that are affected too. Alzheimers New Zealand works with people with dementia, their family/whanau, friends and community. People of all ages, ethnicities and intellectual ability can get dementia. While it is more common in people over the age of 65, it can also affect younger people.

Alzheimer's disease

Alzheimer's disease is the most common cause of dementia (50-70%). As the disease progresses, physical changes occur in the structure of the brain. Brain cells die and the brain shrinks, especially in the inner parts of the temporal lobes. Plaques and tangles form in brain tissue and disrupt messages between brain cells, preventing the brain from working efficiently.

People with Alzheimer's disease experience a gradual decline in their ability to remember, understand, communicate and reason. Some medications are available, which may mask the progression of Alzheimer's disease in the early stages.

You can click here to take an interactive tour that explains how the brain works and how Alzheimer's affects it.

Other common forms of dementia include

Vascular dementia / multi-infarct dementia

Dementia with Lewy bodies

Fronto-temporal dementia

Alcohol-related dementia (Korsakoff's syndrome)

Infection related dementia (Creutzfeldt-Jakob disease (CJD)

Infection related dementia (AIDS-related cognitive impairment)

Dementia can also occur in people with Parkinson's disease, Huntington's disease and Down Syndrome.

Dementia usually causes difficulties with some of the following:

  • remembering
  • thinking and planning
  • making decisions
  • motivation/initiation
  • looking after yourself
  • expressing thoughts
  • understanding what others are saying
  • finding your way around
  • managing finances

Dementia is not:

  • part of normal ageing
  • contagious
  • something to be ashamed of or hidden away
  • something that you have to face alone

Further information:
For further information please go to our resource centre.

Down's syndrome

People with Down's syndrome are at risk of developing Alzheimer's disease in adult life. Research ha…

Huntington's disease

Huntington's disease is a progressive hereditary disease, which most often becomes apparent in adult…

Parkinson's disease

Parkinson's disease is a progressive neurological disease affecting movement. While people with Park…

Infection-related dementia including Creutzfeldt-Jakob disease (CJD)

Creutzfeldt-Jakob disease (CJD) is a rare and fatal brain disorder. Infectious agents, called prions…

Alcohol-related dementia including Korsakoff's syndrome

Heavy drinking over a long period of time can lead to one of the alcohol related dementias called Ko…

Fronto-temporal dementia

Fronto-temporal dementia (including Pick's disease) is a relatively rare type of dementia usually af…

Dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is similar to Alzheimer's disease in that it is caused by the degene…

Vascular dementia

Vascular dementia (also called multi-infarct dementia), is the second most common form of dementia (…

The ten signs

The early signs and symptoms of dementia may be very subtle and hard to recognise. The ten signs lis…

Do I have dementia?

It is common for people of all ages to experience forgetfulness and memory loss. Forgetfulness is no…

Planning for the future

After a diagnosis of dementia, it is a good idea to make decisions about your future as early as pos…

Progression of dementia

When people hear dementia is a progressive disease, they like to know what to expect and when to exp…

Younger people with dementia

Many people assume that Alzheimer's disease and other causes of dementia only affect older people. I…

Dementia: The future is now

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