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Use of cognitive assessment with Alzheimer's Disease

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VOL: 103, ISSUE: 02, PAGE NO: 31

Tony Bush, CertEd, DipN, RMN, is staff nurse, Gwent County Hospital

The assessment of patients as individuals is integral to planning care and treatment. Accurate diagnosis is theref...

COGNITIVE ASSESSMENT AND DIAGNOSIS

The assessment of patients as individuals is integral to planning care and treatment. Accurate diagnosis is therefore essential, especially for early intervention in confirmed or suspected Alzheimer's disease.

The National Service Framework for Older People stresses the importance of distinguishing between dementia, delirium, depression and the effects of drugs, and recommends tests of cognitive, global and behavioural functioning.

Cognitive testing alone does not constitute a definitive basis for the diagnosis of dementia. CT and MRI scans are considered vital in establishing a baseline picture. However, the presence of cerebral damage affects individuals differently.

Once identified, the effects of cerebral damage on cognitive function need to be assessed, as symptom presentation will define individual care and treatment needs.

COGNITIVE ASSESSMENT RATING SCALES

Reilly et al (2004) investigated the range and prevalence of assessment scales in use in old-age psychiatry services in England and Northern Ireland. The majority (96%) of respondents reported that their service used standardised scales as part of the assessment process for older adults with mental health problems. A total of 62 separate instruments were identified and 64% admitted to using three or more assessment scales.

Most frequently cited were the Mini-Mental State Examination (MMSE), the Geriatric Depression Scale and the Clock Drawing Test (CDT). The MMSE is considered the 'gold standard' in measuring cognitive function in people with Alzheimer's disease.

The MMSE was created to differentiate organic from functional organic disorders and could also be used as a quantitative measure of cognitive impairment. However, it was never intended to be used in any diagnostic sense (Burns et al, 2004).

Its widespread use may be in part due to it being the only cognitive assessment scale recommended by NICE in its guidance on prescription criteria for anti-dementia medication. There is evidence to support its use but its effectiveness has been criticised by some researchers. Additional tests may need to be incorporated into the MMSE to improve effectiveness, such as CDT, which is a reliable test of executive function deficit in dementia (Dysch and Crome, 2003).

However, as with many cognitive assessment scales for people with dementia, the bias associated with education levels and physical disability or impairment is not taken into account. Other factors may also influence the results, such as the time of day, the way in which the test is administered and the environment.

A PERSON-CENTRED APPROACH

Alzheimer's disease and other dementias have predominantly been viewed as purely neuropathological phenomena and there has been a tendency to exclude other factors and perspectives. The person-centred approach views dementia as a biopsychological condition (Downs et al, 2005), recognising the multiplicity of factors affecting quality of life, such as neurological, physical, sensory, biographical, personality and social-environmental aspects.

These concepts have emerged from the theory that Alzheimer's disease does not meet the key criterion of a classical disease, that clear pathological features should be present in all cases of symptom presentation and not at all in cases where symptoms are not present (Kitwood, 1999). It is impossible to explain all symptoms and behaviour in all people with dementia by damage to brain tissue caused by plaque formations.

There is a strong theoretical argument (Kitwood, 1999) for viewing neuropathology and social psychology together to explain behaviour of people with dementia. Indeed, severity of behaviour and presentation of symptoms does not always correlate to the degree of physical change to brain tissue.

Key elements in the person-centred approach include valuing and respecting individuals and giving consideration to their personal perspectives. Cheston and Bender (2000) stated that the focus should be:

- On the person with dementia and not on her or his diseased brain;

- On the person's emotions and understandings and not on memory losses;

- On the person within the context of a marriage or family;

- On the person within a wider society and its values.

BEST PRACTICE

It is vital to ascertain which of the patient's abilities are in good working order, which are partially damaged and which are severely impaired. To achieve this, it is important that cognitive tests are perceived as inclusive components of a broader assessment process (Sood et al, 2004). Repeated testing is important to monitor change.

There are no standard guidelines to advise on best practice approaches to using cognitive assessment scales. In particular, the MMSE comes with a set of basic instructions that tells users what to do but not how best to do it.

A comprehensive medical, social and biographical history is vital. The nurse or clinician should review the patient's history before testing by accessing case notes and talking to relatives, carers and other professionals as well as the patient.

During the test, if a patient appears not to understand a question or instruction, the clinician should repeat it patiently and clearly, and check for understanding. The normal ageing processes result in a slowing of the rate at which information is processed and this should be kept in mind.

Neuropsychological assessment of cognitive loss can be a distressing and possibly degrading process. Practitioners must not discriminate against people with cognitive impairments and equally they must not patronise older people (Dewing, 2003). Communication can be enhanced through a friendly, interested and warm approach, speaking slowly and clearly, and explaining things while remaining aware of tone of voice and eye-contact, posture and gesture.

Most cognitive screening tests pay little attention to environmental, physical and sensory influences, which can have significant impact on patients' performance. It is essential to consider the test environment and the patient's functioning before starting by asking a few basic questions to establish physical functioning including hearing and eyesight.

The time of day may also be influential as cognitive function varies over time and from place to place (Bender, 2003). As the day moves on and stress thresholds are breached (Dewing, 2003) people with Alzheimer's disease can exhibit increased cognitive impairment, confusion and agitation. It may be best to undertake cognitive screening in the morning. Repeat testing should be carried out as close to the initial time as possible.

CONCLUSION

The impact of biological processes has a significant influence on cognitive functioning and behaviour, and understanding these processes provides a fundamental basis for care. However, the almost overwhelming effect on physical functioning that accompanies Alzheimer's disease can eclipse psychological factors to become the focus of care and treatment. Concepts driven by the theories of patient-centred care have sought to redress the balance.

No single cognitive assessment or rating scale can be considered definitive. Although the validity of the MMSE has been questioned, it remains the most widely used.

Assessing and treating the individual-specific effects of Alzheimer's disease presents a major challenge. It is not enough to perform cognitive testing in a purely clinical way. Attention must be paid to patients as individuals and approaches to cognitive testing should take this into consideration.

BACKGROUND

- The Alzheimer's Society estimates that over 750,000 people are currently affected by Alzheimer's disease. This is predicted to rise to 850,000 by 2010 and to 1.8 million by 2050.

- Although the normal ageing process adversely affects cognitive function, dementia appears to intensify the deterioration. Dementia accelerates the progressive decline of short-term memory function with more radical global impairment.

- Cognitive assessment of older people with dementia varies, with different practitioners using different assessment criteria, assessment tools and rating scales.

- The National Service Framework for Older People insists on early and accurate diagnosis of mental health problems to meet healthcare needs.

IMPLICATIONS FOR PRACTICE

- Accurate cognitive assessment of older people with Alzheimer's disease ensures effective planning of care and treatment, and the prediction of patients' future care needs.

- It is important to be familiar with the patient's medical, biographical and social history before beginning an assessment.

- Other factors may influence the result of an assessment, such as the way in which it is administered and where. Timing is also relevant - late morning is considered to be the time of optimum cognitive functioning.

- Repeated testing is also important to monitor change.

This article has been double-blind peer-reviewed.

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