What Is Dementia?

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    Dementia is a disease where someone has a decline in their mental functions and cognitive (thinking) abilities.

    Dementia is a term which covers several disorders. Each has different symptoms but they all cause:

    Types of dementia

    Alzheimer’s Disease

    Alzheimer’s disease is the most common form of dementia. It causes microscopic changes in the brain called plaques and tangles.

    In the early stages of the disease, someone with Alzheimer’s will find it difficult to learn new things and their memory will worsen.

    As it progresses, they will have problems in other areas. They might experience:

    • Speech problems
    • Difficulty recognising objects
    • Difficulty with planning and reasoning
    • Changes in their emotions and behaviour

    We don’t know what causes Alzheimer’s disease, although old age and certain genes may make people more prone to it.

    Vascular dementia

    Vascular dementia is caused by an insufficient supply of blood to the brain.

    Although the symptoms vary based on which part of the brain is affected, many people have a change in their attention span and a slowing of their thought processes.

    Someone with vascular dementia may progress steadily or suddenly. When the narrowing of arteries gradually reduces the blood supply to the brain, the progression is steady. When a blood clot cuts off the blood supply to an area of the brain, the progression will be sudden.

    A doctor can make a diagnosis of vascular dementia with patient history and evidence of blood vessel damage such as a heart attack or a brain scan showing a previous stroke.

    Mixed dementia, where someone has Alzheimer’s and vascular changes is common especially in very elderly people.

    Lewy Body Dementia (LBD)

    Lewy Bodies are the name of the protein deposits on the brain of someone with Lewy Body dementia.

    LBD is on the same spectrum as Parkinson’s disease, and the dementia associated with it. Someone with LBD will have symptoms like Parkinson’s disease such as stiffness, shaking and changes in gait. They will also have:

    • Poor attention span
    • Changes in their level of alertness
    • Visual hallucinations (seeing things that aren’t there)

    Sometimes a person with LBD will fall, faint, or thrash about in their sleep as if they are acting out their dreams. Early on, the effect on their memory is not too bad but as the LBD progresses all aspects of their thinking is affected.

    Diagnosis is important to distinguish LBD from delirium, a potentially treatable condition, and to make sure someone with LBD is not prescribed antipsychotic medication which can cause severe side effects.

    As with Alzheimer’s, the cause of Lewy Body dementia is unknown.

    Frontotemporal dementia

    Frontotemporal dementia is a group of conditions which affect the frontal and/or temporal lobes of the brain.

    Unlike other types of dementia, changes to memory and learning ability are less obvious in the early stages.

    A person with frontotemporal dementia is more likely to have changes to their behaviour, personality, or language.

    The behaviour changes may include:

    • Disinhibition – unrestrained or antisocial speech or behaviour
    • Apathy – A lack of interest or enthusiasm
    • Loss of empathy – An inability to understand the thoughts and feelings of others
    • Repeated behaviours or rituals
    • Changes in eating
    • Loss of ability to plan or make judgements

    Language changes may include:

    • Slow or hesitant speech
    • Trouble finding the right word
    • Difficulty naming people and things
    • Problems with grammar and word comprehension

    Frontotemporal dementia is a common cause of younger onset dementia, dementia that happens before someone is 65. It is suspected that there is a genetic cause for people with frontotemporal dementia as 40% have a family history of it.

    Who can get dementia?

    Anyone can get dementia although the likelihood increases as you age. Some people may be predisposed to dementia because of intellectual disability, a history of head injury, or family history of dementia.

    Dementia is very common and as our population ages it is likely that everyone will have contact with someone who has dementia.


    It is important to note if a person shows changes in how they function. The changes might be subtle, a usually reliable person is not paying their bills, or someone who has always been a meticulous dresser goes out with stains on their clothing. This doesn’t necessarily mean that they have dementia. Mental or physical illnesses can cause similar changes, so it is important to see a general practitioner (GP).

    In New Zealand GP’s have access to a “cognitive impairment pathway”. This is a series of steps and tests they used to rule out other conditions and decide whether someone has dementia. Sometimes they may need to refer you on to a specialist or a memory clinic.


    There are no cures for the common forms of dementia. But there is a lot that can help and possibly slow the progression of symptoms. If people get an early diagnosis, it helps them, their family and whānau cope better in the long term. Knowing what to expect helps everyone plan for the future.

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