Assessing a patient for early dementia

A woman's concern about her deteriorating memory may warrant further investigation, explains Dr Sarah Gray.

Jeanette is 58 years old. There is nothing remarkable on her medical summary and you have not seen her for two years. She last visited with a sinus infection.

Dementia affects about one person in 1,000 among under-65s

At that time, she was also struggling to cope with her elderly, confused mother, who lived nearby. Jeanette is concerned she may be going the same way because her memory is not what it was.

A glib response such as 'neither is mine' is not acceptable in these circumstances - this presentation requires further exploration. A gradual deterioration in higher cerebral function occurs with age. The task here is to identify whether the loss falls outside the normal range and what impact it is having on functional ability.

The diagnosis of dementia requires a significant loss of mental ability, with functional limitation. It is essentially a clinical diagnosis but a number of validated instruments, such as the 30-point mini mental state examination, can provide a degree of objectivity.

Dementia
Dementia is commonly seen as a problem of the very old and certainly its prevalence increases with age. It can, however, affect younger people, with a risk of about one in 1,000 for under-65s.

The challenge is to identify these patients and assess their suitability for medication that might slow the progress of the condition. There are profound consequences for employment and family life that early recognition and support could address.

A series of questions will shed light on what is happening. What has Jeanette noticed and how long has this been going on? Is it changing with time and how rapidly? What else is going on in her life? What does she find difficult? Have other people noticed? Is she aware of any physical or health problems?

Validated assessment tools
If you are still concerned, you may wish to use one of the short, validated assessment tools. The abbreviated mental test score has been widely used in hospitals, but has not been validated for screening in primary care. The RCGP-preferred alternative is the six-item cognitive impairment test (see box below).

With a potential 28 points, scores of zero to seven are regarded as normal, and more than eight as significant. This cut-off is reported to have 90 per cent sensitivity and 100 per cent specificity.

Hormonal influence
Your analysis should work through the more likely possibilities first. Is this presentation purely postmenopausal? Postmenopausal women commonly complain of difficulty in concentration and memory and, in particular, word finding.

Estrogen is recognised as having a role as a central transmitter and there is a high concentration of estrogen receptors in the part of the cortex responsible for verbal memory. Isolated word finding difficulty might be ascribed to estrogen deficiency.

Associated sleep disturbance could contribute via tiredness and subsequent difficulty in concentrating. There is evidence that women who lose ovarian function early have a higher risk of dementia in later life. Work is being carried out to determine whether continued exposure to premenopausal estrogen levels maintains cerebral function.

Address other possible contributory factors. Has Jeanette's mother died and is she experiencing a bereavement reaction? Is her mother alive and causing stress, or does another crisis explain the change? Has she developed a depressive illness?

Causes
A diagnosis of dementia covers a spectrum of potential causes, from diseases affecting the brain, interrupted blood supply, or pressure (tumours, for example), to head injury. Sixty per cent are Alzheimer's type. Some of the others, such as excessive alcohol or hypothyroidism, will be treatable by treating the root cause, and some have risk indicators that can be addressed to mitigate progression.

Twenty per cent of dementias are vascular in origin. It is worth reviewing your patient's cardiovascular risk profile because these are also mid-life risk factors for later Alzheimer's disease.

We tend to forget that postmenopausal women are just as likely as men to develop - and more likely to die of - arterial diseases. Check smoking and BP. Ask about alcohol intake, which may be higher than Jeanette appreciates. Ask whether she takes or uses anything else.

A variety of neurodegenerative diseases may present in this way so excluding other symptoms is important. Simple investigation can be initiated in the surgery. These might include FBC, B12 and folate, ESR, U&Es, liver (including gamma glutamyl transferase) and bone profiles, TFTs, fasting glucose and lipids, and syphilis serology.

In some women, HIV testing might be appropriate. Drug monitoring or prescribed drug levels could be necessary or, if indicated, an MSU.

There is evidence that mild cognitive impairment tends to progress to dementia. If in doubt, you should refer Jeanette for more formal assessment. Ideally, this would be to a memory clinic, although these are not established in all areas. A psychiatrist with an interest in memory would be an appropriate route.

Further assessment, including imaging, can then be arranged. If Jeanette's concerns are valid, the specialist team can instigate the discussion regarding treatment and support, and you will have done your best for her.

Click here for the six-item cognitive impairment test

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