Normal ageing and dementia

Dementia is not a part of normal ageing

Many people are complaining about their cognitive abilities, mostly about memory, when they grow older. They may need more time to remember things, may be more easily distracted, or struggle with multitasking. It can be difficult to distinguish whether these changes are normal or if a person should worry and visit a doctor.  One of the reasons why dementia is often not diagnosed at the early stage is that the public and often also professionals consider the signs and symptoms of dementia to be a normal part of ageing. To change this, a clear concept of the differences between normal ageing and dementia is required.

Criteria for distinguishing between normal ageing and dementia

In most cases (e.g. in neurodegenerative diseases) dementia evolves gradually, and there is no sharp borderline between normal ageing and incipient dementia. However, there are three simple criteria that distinguish the two: (1) The rate of change over time; (2) the persistence of impairment; (3) the impact of impairment 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.

Trajectory of fluid intelligence in normal ageing and dementia

  1. Persistence of impairments: Since, particularly in neurodegenerative diseases, impairments of cognitive ability and activities of living as well as behaviour alterations are caused by irreversible damage and loss of nerve cells and nerve cell connections, symptoms persist and gradually worsen over time. Episodically occurring lapses of attention, memory, orientation, or word finding are not usually indicative of incipient dementia.
  2. Impact on activities of daily living: By definition, dementia is characterised by cognitive and / or functional impairments that are severe enough to interfere with activities of daily living that are normal for the person involved. Mild and occasional forgetfulness or word finding difficulty that has no effect on the individual’s everyday performance is not part of dementia, although such minor symptoms („mild cognitive impairment“) may gradually progress to dementia over several years. Of note, well-educated individuals may be able to compensate a significant degree of cognitive impairment with the effect that their everyday performance remains unchanged.

Comparing the signs of normal ageing and dementia

The table below lists examples of the possible changes due to normal ageing or early dementia, to illustrate the subtle differences. They apply to the most common types of dementia, particularly to dementia due to Alzheimer’s disease.

Comparing the signs of normal ageing and dementia

Normal ageingDementia
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