Normal ageing and dementia

Dementia is not part of normal ageing. As people age, they may experience memory problems and other cognitive difficulties. One of the reasons why early stage dementia is often overlooked is that many people believe the symptoms are part of the normal ageing process. In order to recognise the disease early and act appropriately, it is important to have a clear understanding of the difference between normal ageing and dementia.

Criteria for distinguishing between normal ageing and dementia

In most cases (i.e. neurodegenerative diseases of the brain), dementia develops gradually and there is no clear boundary between normal brain ageing and the onset of dementia. However, three simple criteria can be used to distinguish between the two conditions:

  1. The rate of change over time.
  2. The persistence of the impairments.
  3. The impact on activities of daily living.

1. Rate of change over time

Some cognitive abilities decline with advancing age. This is particularly true for cognitive abilities that require the acquisition and processing of new information such as recall of recent events, organising and problem solving, and cognitive speed. These abilities are sometimes called „fluid intelligence“. However, in normal ageing the rate of change over time is very slow and deterioration will not become noticeable within a few months or even years. Other cognitive abilities including knowledge of the world remain largely stable.

2. Persistence of impairments

Dementia leads to a persistent and irreversible decline in mental functions. Temporary difficulties with concentration, memory or orientation are not usually signs of dementia. Only when symptoms persist for longer than six months is it considered dementia.

3. Impact on activities of daily living

Dementia is characterized by significant limitations in daily activities. Mild and occasional memory gaps or difficulty finding words that do not interfere with daily life are not signs of dementia. However, such mild symptoms (known as "mild cognitive impairment") can progress to dementia over the course of several years.

Comparing the signs of normal ageing and dementia

The following table gives examples of changes in normal ageing and early dementia to illustrate the subtle differences. These examples relate to the most common forms of dementia, particularly Alzheimer's disease, and involve different areas:

  Normal ageing Dementia
Memory and learning – Sometimes forgetting peoples’ names or appointments, but remembering later
– Occasionally forgetting what was told
– Misplacing things from time to time
– Forgetting the names of close friends or family, or forgetting recent events
– Asking same questions over and over
– Putting objects in unusual places, e.g. putting keys in bathroom cabinet
Planning, problem solving, and decision-making (executive functions) – Being a bit slower to react or think things through
– Getting less able to juggle multiple tasks
– Making a bad decision once in a while
– Occasionally making a mistake when doing family finances
– Getting very confused when planning or thinking things through
– Having a lot of difficulty concentrating
– Frequently poor judgment when dealing with money or when assessing risks
– Having trouble keeping track of bills
Language – Having a bit of trouble finding the right word sometimes
– Needing to concentrate harder to keep up with a conversation
– Losing the thread if distracted or many people speaking at once
– Having frequent problems finding the right word
– Having trouble following or joining a conversation
– Regularly losing the thread of what someone is saying
Orientation – Getting confused about the day or the week but figuring it out later
– Going into a room and forgetting why went there, but remembering later
– Losing track of the date, season and the passage of time
– Getting lost or not knowing where a person is in a familiar place
Visual perceptual skills – Vision changes related to cataracts or other changes in the eyes – Problems interpreting visual information; e.g. difficulty judging distances on stairs
Mood and behaviour – Sometimes being weary of work, family and social obligations
– Sometimes feeling a bit low or anxious
– Becoming irritable when a routine is disrupted
– Withdrawing, losing interests
– Getting unusually sad, anxious, frightened or low in self-confidence
– Becoming irritable or easily upset at home, at work, with friends