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Is it early dementia - or just old age?

Neurologist Dr Daya Gunawardena considers the challenge for GPs in assessing the first, more ambiguous, stages of cognitive decline

Neurologist Dr Daya Gunawardena considers the challenge for GPs in assessing the first, more ambiguous, stages of cognitive decline

Is it an early dementia or the consequence of normal ageing? This is the question that springs up whenever an older person consults and complains that his or her memory is much worse. It is not as simple a question as it may sound; often it cannot be easily answered.

This diagnostic dilemma is not confined to GPs and is also seen in memory clinics in secondary care.

Many older people rightly accept a degree of memory impairment with ageing and so do their family. Memory declining with age has been a recognised feature for thousands of years and there are accurate descriptions of it from Ancient Egypt.

Although memory loss has been ascribed to the ageing process, people have always lived to extremely old age without significant memory loss. In contrast Alois Alzheimer's first description of Alzheimer's disease was in a woman aged just 51.

Terms such as benign senescent forgetfulness and age-associated memory impairment have been used to describe the memory decline that occurs physiologically with advancing years. Working out exactly what is normal ageing is always difficult, as some people are old and physically healthy whereas others have a number of concomitant physical illnesses which can affect cognitive function.

Multiple medication regimens, which many older people are on, may also affect cognition. An allowance has to be made for educational status; bearing in mind that a high educational status acts as a buffer against cognitive disorders. The loss of cognition with age is not inevitable, but it is common.

Some of the cognitive changes with ageing can be so subtle as to not manifest as poor scores on cognitive function tests. The real problem has been to attempt to clearly define the limits of normal or physiological memory impairment with ageing and distinguish it from the beginnings of a dementing illness.

Distinguishing between age-related changes and early dementia is a difficult and challenging problem and time may be the only clear-cut way to separate the two. While benign senescent forgetfulness or age-associated memory impairment are terms that have been used to describe the normal impairment of memory1 with ageing, the term mild cognitive impairment, (MCI) used first in 1990, refers to people with mild difficulties of cognition which do not meet the full criteria for dementia, yet is considered pathological – an intermediate stage that invariably leads to dementia.

In MCI, social competence and activities of daily living are not compromised in any significant way.

People with MCI fulfil a set of criteria, although not universally accepted. The diagnostic criteria for MCI2 are shown here.

Anatomically, MCI subjects present with a reduced hippocampal volume related to atrophy which can be detected with the use of MRI. Postmortem data reveals the presence of characteristic Alzheimer's disease features in about half of the MCI subjects3.

Prevalence of MCI is 1% at the age of 60 and increases up to 42% at the age of 854. Persons who meet the criteria of MCI tend to progress to clinically probable Alzheimer's disease at a rate of 10 to 15% a year, which means that some 80% of MCI subjects will have converted to dementia in a period of six years5.

In taking the history, the clinician should note the following:

• Though the subjective impression of the patient regarding memory problems is a valid one, the physician should not rely only on this information.

• Relative, partners or carers should be consulted

•An important question is to ask about changes in memory compared with what it was previously; it is also useful to ask about the ability to solve problems and to handle tasks the patient used to be able to perform well

Further questions to ask

• How long has the memory problem been present?

• Has it been gradual/episodic?

• What triggered it?

• What is the worst time of day?

• Sleep problems?

• Depression?

• What are the details of any ‘major' episodes of disorientation/confusion?

• What is the family history?

• What medication is the patient on?

• Are there any concomitant physical diseases?

• What is your vision and hearing like?

• Have you had any fits, faints or falls?

It is also important to exclude depression, delirium or an acute confusional state as well as other reversible causes of dementia, secondary causes such as slow-growing brain tumours and subdural haematomas.

The following assessments are useful in the clinic setting:

• MMSE – mini mental state examination

• CDT – clock drawing test

• ADL scale (Bristol)

•GDS – depression scale



•CT brain/MRI


•Haematology – FBC, vit B12 folates

•Biochemistry – sugar, LFTs, lipids, TFTs, U&Es

• Tests for syphilis

MCI is a pathological condition invariably leading to dementia. It is a point at which social competence and activities of daily living are maintained at an acceptable level. Deterioration that affects social competence and activities of daily living would lead to a diagnosis of dementia.

Interest in the continuum from normal cognition to MCI and then on to early Alzheimer's disease has increased considerably, more so since the approval of pharmacological agents for the symptomatic treatment of Alzheimer's disease.

To distinguish between MCI and early dementia is difficult as the changes are so insidious and subtle. The involvement of cognitive domains other than memory, such as speech and language, executive function and visuospatial disturbances, is when MCI reaches the realms of dementia.

Cardiovascular risk factors such as hypertension, diabetes and elevated cholesterol have all been incriminated as aetiological factors with the development of MCI and dementia.

It was once thought that Alzheimer's disease and vascular dementia were different conditions, but they are now regarded as the same condition, with slightly different presenting features. Vascular risk factors are incriminated in both forms of dementia, vascular and Alzheimer's6. These two forms often co-exist.

The anticholinesterase treatment of MCI and early dementia is still not universally accepted, particularly by NICE in its latest guidelines7, although there is a substantial school of thought that advocates early intervention with anticholinesterases.

Dr Daya Gunawardena is consultant neurologist at University Hospital, Lewisham


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