What is Dementia?

Dementia is the term used for a number of conditions whose symptoms affect memory and other functions such as language, problem solving, thinking and behaviour. For a diagnosis of dementia to be made these difficulties need to impact on a person’s everyday functioning, and any other causes for these changes need to have been ruled out.

Everyone with dementia is unique and symptoms affect people differently. Symptoms are progressive, meaning they gradually worsen over time.

Symptoms may include:

  • Memory impairment – for example, forgetting recent events, missing appointments
  • Language disturbance, such as forgetting words or using incorrect words
  • Difficulty recognising or identifying objects- for example putting washing up liquid in the fridge
  • Trouble with organising, planning and judgement – for example difficulty with problem solving or cooking a meal
  • Visuospatial and motor skills such as judging distances and physical coordination
  • Changes in mood and behaviour –for example becoming withdrawn and apathetic.

Information Sheet

What causes dementia?

Alzheimer’s Disease
This is the most common form of dementia. It usually begins with a decline in memory and the ability to learn new things. Later, during a steady, gradual deterioration, there are problems in other areas (for example speech, planning or reasoning, recognising objects, changes in emotions and behaviour). The cause of Alzheimer’s Disease is unknown, although old age and certain genes appear to make people more prone to it. In the brain, there are microscopic changes, “plaques” of a substance known as amyloid and “tangles” within dying nerve cells.


Vascular Dementia
This occurs when there is insufficient blood supply to the brain. The symptoms are variable depending on which part of the brain is affected, though changes in the ability to pay attention, slowing of thought and frontal-lobe changes (see below) are common. The progression may be steady if the blood supply is gradually reduced by the narrowing of small arteries. Alternatively sudden or “stepwise” progression occurs if the blood supply suddenly closes off to an area of the brain, often because   a blood clot has formed or has been carried from another location. The diagnosis is made from the history and evidence of blood vessel damage e.g. previous stroke seen on a brain scan or heart attack.

It is quite common especially in the very elderly to have “mixed dementia”, that is, both Alzheimer’s and vascular changes.


Lewy Body Dementia
This condition is the third most common cause of dementia, around 20% of dementia cases. Lewy Body Dementia is on a spectrum that includes Parkinson’s disease and the dementia associated with that condition.

People with Lewy Body Dementia have symptoms similar to those of Parkinson’s disease, such as stiffness, shaking, slowness and changes in gait. Cognitive changes include poor attention, changing levels of alertness and visual hallucinations (that is, seeing things that are not there). Sometimes those with Lewy Body Dementia fall, faint or thrash about in their sleep as if acting out their dreams. Memory is typically not too impaired early on, but as the condition progresses all aspects of thinking are more widely affected. It is important to make the diagnosis to distinguish it from delirium, a potentially treatable medical condition, and to ensure the person is not given antipsychotic medication which can have severe side-effects in Lewy Body Dementia. In this condition we see large spherical protein deposits in the brain – these are Lewy Bodies. The cause is unknown.


Frontotemporal Dementia
In this group of conditions the frontal and /or temporal lobes of the brain are affected. Memory loss and learning problems are less obvious early on and the main symptoms are changes in behaviour and/or personality and/or language. The sorts of behavioural changes seen are disinhibition (e.g. unrestrained or antisocial speech or behaviour), apathy (not initiating or doing anything), loss of empathy (understanding of others’ thoughts or feelings) repeated behaviours or rituals, changes in eating and loss of ability to plan or make good judgements. Language changes include slow or hesitant speech, word-finding, naming, grammar and word comprehension. Frontotemporal dementia is a common cause of early onset dementia (beginning before the age of 65) and about 40% of people with frontotemporal dementia have a family history, suggesting there is a genetic cause.


Who gets dementia?

While there are known risk factors and protective factors associated with developing dementia there are no guarantees as to who will or won’t develop dementia.

Dementia becomes more common as people grow older. It is estimated that approximately 60 000 New Zealanders have dementia. About 1 in 100 people in their 60s are estimated to be affected and 1 in 3 people over the age of 90. The number of people living with dementia is expected to rise sharply in the next few decades as our growing ageing population lives longer. Increased knowledge about dementia also means some people are being diagnosed earlier in the disease process.

It is estimated that over 3 000 New Zealanders under the age of 65 years have dementia.

What is the treatment for dementia?

There is no cure for dementia but there are medications available that may help some people, for some time, to function better than they otherwise would. One of these, Donepezil is subsidised by Pharmac. Talking therapies like counselling can also help people to come to terms with the changes that a diagnosis of dementia brings and the feelings that can arise.

Much of the treatment of dementia is social rather than medical. If you have dementia or are supporting someone with dementia it is important to maintain interests, social contacts, self-esteem and purpose in life. When people with dementia are encouraged to remain as independent as possible in their activities of daily living, their quality of life is better. Exercise and a healthy diet are also important factors in living well with dementia.

The majority of people with dementia live in the community. With good support, people with dementia can continue to live full and meaningful lives.

Early warning signs of dementia

The brain changes that are thought to cause dementia may have been slowly building up for many years, even decades, before a person begins to show clinical symptoms. Early signs can be vague and not immediately obvious. Given that there can be some age related changes in memory this can cause people to become concerned they have dementia. Occasionally forgetting a friend’s name or losing your keys does not mean you have dementia.

However, anyone who is worried about noticeable changes in their memory or other related symptoms are advised to discuss their concerns with a G.P. This ensures other causes for these changes can be treated where appropriate. Brain functioning can be affected by many things including stress, grief, depression and physical illnesses. If the symptoms are a result of dementia then an early diagnosis can provide access to medications, support and information.