Health

Dementia and cognitive decline 101

Dementia and cognitive decline are not normal parts of ageing, but a disease that demands management and caring. It’s tough for the person diagnosed, but can be tougher on those caring for them. Alex Brooks explains.

By Alex Brooks

Dementia can be a scary word - but it needn’t be. Just like cancer and cardiovascular disease, it should be openly discussed and managed.

It’s already one of the leading causes of death in New Zealand, according to World Health Organization (WHO).


Dementia is an umbrella term used to describe the symptoms of more than 100 illnesses which cause a progressive decline in a person’s functioning, including things like: loss of memory, intellect, rationality, social skills and physical functioning. 

There are many types of dementia including Alzheimer’s disease, vascular dementia , frontotemporal dementia and Lewy body disease

Dementia can happen to anybody – actor Bruce Willis has been diagnosed with frontotemporal dementia, former British Prime Minister Margaret Thatcher had also been diagnosed and comedian Robin Williams had Lewy body – but dementia is more common after the age of 65. Younger onset dementia can affect people aged in their 30s, 40s or 50s.


The difference between cognitive decline and dementia

Dementia is usually diagnosed when cognitive impairment has become severe enough to compromise social functioning. 

Heathdirect says if someone you care for or live with has cognitive impairment, you may notice:

  • they sometimes feel confused, agitated or distressed
  • a change in their speech or behaviours
  • that they struggle to finish their daily tasks

Mild cognitive impairment (MCI) is a state intermediate between normal cognition and dementia, with essentially preserved functional abilities. Healthify offers a free support program for mild cognitive impairment.  

No cognitive impairment (NCI) is said to be a state that characterises normal ageing or a cognitively impairing disorder that is not severe enough to produce any change in abilities


Subjective cognitive impairment (SCI) is perceived or subjective decline in cognitive or functional abilities that does not keep an individual from performing any of their usual or most complex activities. People experiencing SCI may be aware there is a decline in their abilities but they are still able to compensate. In Alzheimer’s disease, the SCI stage lasts around 15 years.

Mild cognitive impairment (MCI) is a decline in cognitive abilities such as language, memory reasoning, judgement, or perception that is not due to normal ageing. Individuals in the MCI stage may still independently drive, shop, cook, pay bills, manage finances and do household chores. This is not a normal part of ageing.


Dementia is the level of severity after the MCI stage in most cognitively impairing disorders. This is usually the stage of formal medical diagnosis (sometimes it happens in the MCI stage) but it’s when it becomes hard for a person to cook, drive, pay bills, do house work or tend to personal hygiene. Dementia can also progress to affect walking, speech, swallowing and controlling your body, neck and face.  

Read more on Healthdirect about how technology is helping people with dementia.

How to avoid dementia

The World Health Organisation is treating dementia as a global health priority and has made 12 recommendations to help reduce its risk, including:

  1. Be physically active
  2. Stop smoking
  3. Eat a balanced healthy diet – you might like to try the flexible Mediterranean diet
  4. Drink alcohol in moderation
  5. Cognitive training
  6. Be socially active
  7. Look after your weight
  8. Manage any hypertension
  9. Manage any diabetes
  10. Manage any cholesterol
  11. Manage depression
  12. Look after your hearing.

Citro partner nib explains 3 ways to reduce dementia risk. You can also read more on Citro’s 10 simple lifestyle swaps for longevity gains guide.

7 stages of dementia

Cognitive impairment or memory loss is different to a diagnosis of dementia.

Queensland’s Brain Institute has outlined the 7 stages of dementia:

1. Appears normal

Normal, no obvious signs, although brain changes may be occurring.

2. Very mild

No noticeable symptoms different to normal ageing. Brain imaging may reveal plaques or degeneration.

3. Mild

Mild cognitive deficits – increased forgetfulness or disorientation, difficulty finding words. Loved ones begin to notice decline.

4. Moderate

Memory of recent events affected; difficulty with complex tasks and managing personal affairs; may be in denial or withdrawn from family. Decline is obvious to a doctor. Family and friends notice symptoms.

5. Moderately severe

Major memory lapses, including significant life events; needs help with daily activities such as dressing or preparing meals; can no longer manage personal affairs. 

6. Severe

Can no longer care for self; starts to forget names of family members; difficulty finishing tasks; speech affected; incontinence, depression, agitation, delusions may be evident.

7. Very severe

Full time care is needed; loss of speech; requires assistance with all daily activities, including eating, bathing, toileting; may lose the ability to walk.

Queensland’s Brain Institute says the average time from the appearance of obvious symptoms of different types of dementia until death can be about 8-10 years for Alzheimer’s disease; 4-8 years for Lewy body and frontotemporal dementias; and 5 years for vascular dementia. Remember, these are guidelines only and everyone experiences dementia differently.

Resources to help families experiencing dementia

The information on this page is general information and should not be used to diagnose or treat a health problem or disease. Do not use the information found on this page as a substitute for professional health care advice. Any information you find on this page or on external sites which are linked to on this page should be verified with your professional health care provider.

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