Cognitive assessment of older adults with Alzheimer's disease
ABSTRACT Bush, T. (2007) Guidelines for the cognitive assessment of older adults with Alzheimer’s disease. www.nursingtimes.net.
Accurate cognitive assessment of older people with Alzheimer’s disease is an essential part of the diagnostic and monitoring process to ensure effective planning of care and treatment and prediction of patients’ future care needs. This article discusses the rationale for cognitive assessment and the most widely accepted rating scale, and assesses the process of administering cognitive assessment in a patient-focused way. It also summarises best practice in cognitive testing.
The Alzheimer’s Society (2004) estimates that over 750,000 people are currently affected by Alzheimer’s disease. This is predicted to rise to 850,000 by 2010 and 1.8 million by 2050.
There is some confusion over what constitutes Alzheimer’s disease (Gilleard, 2000). Neurofibrillary tangles and senile plaques, initially thought to be the main neuropathological phenomena of Alzheimer’s, have been found to occur in the brains of older people suffering with dementia as well as those who do not. Social, genetic and toxicological research has also proved inconclusive. Even the distinction between senile and pre-senile dementia is blurred, with the same types of atrophy (shrinkage) and destruction of individual nerve cells in the brain occurring in both (Cheston and Bender, 2000). There is, however, a general agreement that dementia affects physical, psychological and social functioning.
Cognitive assessment of older people with dementia varies, with different practitioners using different assessment criteria, assessment tools and rating scales, but those that are used have a number of fundamental flaws that impede their accuracy and validity as diagnostic tools. However, practitioners need something to guide them in the prescription and evaluation of care, and treatment and assessment processes must be in place.
This article explores the concepts, methods, research, texts and scales available for cognitive assessment of older people with Alzheimer’s disease in order to extract the most relevant and meaningful components of the assessment process and make recommendations for good practice.
Biological effects on the brain
Cognition is a sophisticated brain function that includes memory, language, problem-solving, gestures and recognition. Each of these domains can be split into components - memory, for example, into working memory (the here and now), procedural memory (learnt tasks and skills) and semantic memory (knowledge of the world). All components of cognition are linked and impairment of one or more leads to dysfunction, to varying degrees, in the others.
Age-related cognitive decline is distinct from that associated with Alzheimer’s disease, relating more to progressive memory impairment (Peterson et al, 2001). Although the normal ageing process adversely affects cognitive function, dementia appears to intensify the deterioration. For example, with age, the ability to remember recent events is poorer although the capacity to recollect situations in the distant past can be quite vivid (Jones, 1996). Dementia accelerates the progressive decline of short-term memory function with more radical global impairment.
Gilleard (2000) describes Alzheimer’s disease as a neurodegenerative disorder characterised by a specific pathology in the brain. Characteristic features include senile plaques (extracellular deposits in the cortical tissue containing a core of abnormal B-amyloid protein surrounded by degenerating neuritis) and neurofibrilliary tangles, which are bundles of intracellular twisted neurofilament proteins (Cummings and Back, 1998).
The way in which dementia affects brain physiology influences the impairment of cognition and cognitive processes (Fig 1). The temporal lobes are the brain’s memory centre (Delieu and Keady, 1996). Verbal memory is held on the dominant side (left for right-handed people), while visual memory resides on the non-dominant side. Remote memories are stored deeply inside the temporal lobes, so in dementia affecting the cortex (surface) recent memory deteriorates first. Such damage results in short-term memory loss.
The parietal lobes are the analytical centre of the brain. The dominant side is responsible for speech, understanding, calculation, writing and reading. This centre links with the temporal lobe for memories of words. Damage here results in expressive dysfunction, problems in word-finding and expression and receptive dysphasia or difficulty in understanding others (Eastley and Wilcock, 2005). The non-dominant side is responsible for provision of a sense of space and geography - it is important for negotiating and comprehending environments and adapting to environment change. Damage results in symptoms of disorientation in space and time. Both sides link to provide a capacity for recognition of things for what they are and purposive movements. Damage causes visual agnosia or non-recognition of objects or people. Symptoms of apraxia (impairment of purposive actions such as dressing, driving, cooking) and disturbance of ideational praxis (the meaningful translation of ideas into actions) frequently occur (Karen et al, 2001).
The frontal lobes of the brain are responsible for executive function and adult behaviour. Executive function depends on integrating memory, emotion and sensory input to decide on a specific action or series of actions (Cummings, 2003). This complex process involves three main centres - the lateral surfaces, the medial centre and the orbitobasal area. The lateral surfaces facilitate planning and organising as well as being responsible for learning skills, until they become automatic and are then governed by the parietal lobes. Damage to these areas results in a decreasing ability to learn new skills, as well as gradual loss of planning and organising capabilities. The medial centre situated behind the eyes acts as a catalyst for activity. Impairment of this area is characterised by problems with initiating procedures. It can also result in the initiation of an activity that cannot be stopped, causing individuals to repeat activities or phrases over and over - a situation known as ‘perseveration’ (Cummings, 2003).
The orbitobasal centre, situated immediately above the eyes, regulates socially acceptable behaviour norms. Impairment results in wandering, disinhibition, shouting, swearing or aggressive behaviour. Alzheimer’s disease is associated with social, behavioural and personality changes, often resulting in problems with impulse control and antisocial and stereotypical behaviour (Farcnik et al, 2002).
All three areas of the frontal lobes connect and interact to provide insight into appropriateness of behaviour and social conduct. In Alzheimer’s disease there is a progressive failure of insight-feedback-verification, causing loss of insight and often the undertaking of risky or dangerous activity (Crutch, 2002). Between the frontal and temporal lobes is a connecting system known as the limbic system, which integrates behaviour with memory and emotions, damage to which results in patterns of misinterpretation.
Individuals with Alzheimer’s disease are progressively caught up in miasma of psycho-behavioural and psychosocial dysfunction, distortion and confusion. The pattern of brain damage varies between individuals and will result in a variable pattern of symptoms. Individuals’ transition, response and adjustment to this evolving process are also unique (Delieu and Keady, 1996).
Cognitive assessment and diagnosis
Assessment of patients as individuals is integral to the planning of 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 (DH, 2001) insists on early and accurate diagnosis of mental health problems to meet healthcare needs. It also 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 are considered vital in establishing a baseline picture. CT may reveal hydrocephalus, generalised atrophy or focal atrophy in syndromes such as frontotemporal lobar degeneration, while MRI is more sensitive to vascular changes and provides better delineation of structural changes in the brain. These procedures aid diagnosis and can indicate damage to specific areas which result in cognitive dysfunction.
However, the presence of cerebral damage affects individuals differently. Once identified, the effects of the damage on cognitive function needs to be assessed, as symptom presentation will largely define individual care and treatment needs.
An ideal comprehensive cognitive assessment would take into account all potential variables that impact on an individual’s cognitive function, but this is probably not achievable. It has been suggested that specific cognitive changes indicate the need for assessment for dementia, such as new forgetfulness, more trouble understanding spoken and written communication, difficulty finding words, not knowing common facts, such as the name of the current prime minister, and increasing environmental disorientation (Rabins et al, 1999). In addition a checklist of impaired cognition in the symptom evaluation of dementia is advised (Box 1).
Box1. Domains of impaired cognition (Rabins et al, 1999)
The American Psychiatric Association (1994) warns of the potential for confusing clinical dementia with age-related cognitive decline. Multiple cognitive deficits such as memory impairment, aphasia, apraxia, agnosia and disturbance in executive functioning are characterised by gradual onset and continuing cognitive decline, and that diagnosis should be supported by neuroimaging.
The symptoms of dementia should also occur in the absence of other central nervous system diseases that cause progressive deficits in memory and cognition such as cerebrovascular disease, Parkinson’s disease, Huntington’s disease, subdural haematoma, normal-pressure hydrocephalus or a brain tumour. Further exclusion extends to systemic conditions known to cause dementia, such as hypothyroidism, vitamin B12 or folic acid deficiency, niacin deficiency, hypercalcaemia, neurosyphilis or HIV. It is also important to explore whether symptoms are related to substance-induced conditions or other psychiatric disorders such as depression or schizophrenia. While the clinical presentation of dementia may vary the diagnostic features are constant (Karen et al, 2001).
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 through a postal questionnaire to old-age psychiatrists from the Royal College of Psychiatrists membership lists.
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 (this ranged from 1-12).
The most frequently cited measures were the Mini-Mental State Assessment Examination or MMSE (95%), the Geriatric Depression Scale (52%) and the Clock Drawing Test (CDT). Originally 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 (2006) in its guidance on prescription criteria for anti-dementia medication.
There seems little doubt that the MMSE is considered the ‘gold standard’ in measuring cognitive function in people with Alzheimer’s disease, not only in the UK but also throughout Europe and in the USA. 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 its effectiveness. Dysch and Crome (2003) recommended combining the CDT with it to evaluate executive function. Executive function deficit (EFD) is generally linked to frontal lobe impairment and may indicate brain damage as a possible result of neurodegenerative disease.
The CDT allows for a qualitative interpretation of how well the patient conceptualises the relationship of time to numbers (Mendez et al, 1992). It has been described as a brief, insightful, reliable and valid test of EFD 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 when the test is administered, the way in which it is administered and the environment in which it is undertaken.
Bowie et al(1999) examined variability in clinicians administering the MMSE to a group of their colleagues. A normal or correct score using this scale is considered to be 20 points or above. The range of scores obtained was 14-27, so some people who clearly have unimpaired cognitive function would have fallen into the same category reserved for individuals with dementia.
Some authors have recommended adapting the cut-off scores of tests such as the MMSE according to sociodemographic characteristics (Tangalos et al, 1996; Crum et al, 1993). This has important limitations because age, sex, low educational level (Di Carlo et al, 2002) and occupation (Herrera et al, 2002) are also considered to be risk factors for dementia.
Adjusting for education reduces the risk of observing a false association between dementia and low test performance, but increases the probability of not discovering a real association between dementia and low educational level (Kittner et al, 1996). In addition, the most common screening methods for cognitive impairment require a minimum level of education since they entail the ability to read, write or make calculations (Yebenese et al, 2003).
In a study exploring the limited validity of the MMSE in screening people for dementia in primary care, White et al (2002) trained practice nurses and GPs to administer the scale during annual health screening for people over the age of 75. Patients who scored on or below the MMSE cut-off point of 26/30 were offered further assessment by a member of the research team at home using the GMS-AGECAT diagnostic system. The researchers reported that the MMSE had an unacceptably high false positive rate of 86%, and recommended that case identification be based on history and complaints of memory problems from patients and carers and not cognitive testing alone.
Current UK healthcare policy insists on the introduction of the single assessment process (SAP) for the health and social care of older people (DH, 2002) to ensure that the scale and depth of assessment is kept in proportion to people’s needs, that agencies do not duplicate assessments and that professionals contribute to assessments in the most effective manner.
The DH (2004) has accredited six off-the-shelf tools for overview assessment. It advises that assessment tools should be valid, reliable and culturally sensitive, and should not unfairly discriminate against people on the grounds of age, gender, race, disability or any other factors. The only recommended scales for the assessment of cognitive function and impairment are the MMSE (Folstein et al, 1975), short orientation-memory-concentration test of cognitive impairment (six items) - itself a derivative of MMSE (Katzman et al, 1983) - and the Gujurati version of the MMSE (Lindesay et al, 1997).
Salmon and Lange (2001) concluded that although many tools such as MMSE have been proposed for screening older people with suspected Alzheimer’s disease their results are partially influenced by age, education, ethnicity, language, sensorial limitations and other systemic processes.
A PERSON-CENTRED APPROACH
Alzheimer’s disease and other dementias have predominantly been viewed as a purely neuropathological phenomenon 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, including neurological, physical, sensory, biographical, personality and social-environmental aspects. An alternative conceptual framework evolved which drew ideas from social psychology and psychotherapy. Significant non-biological influences in dementia such as malignant social psychology were identified and tools such as Dementia Care-Mapping were developed.
These concepts have emerged from the theory that Alzheimer’s disease does not meet the key criterion of a classical disease, in 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 (Dewing, 1999). There is a strong theoretical argument (Kitwood, 1999) for viewing neuropathology and social psychology together to explain the behaviour of people with dementia. Indeed, the severity of dementia behaviour and symptom presentation does not always correlate to the degree of physical change to brain tissue.
Although Kitwood (1999) acknowledged the ‘overwhelming organicity’ of Alzheimer’s disease and appreciated why the medical profession takes a technological approach to treatment he argued that this approach is to the detriment of personhood. The clinical methodology of care, whereby the individual is almost reduced to an object on which treatments and testing are routinely performed (with or without her or his consent), was further crystallised by Kitwood (1999) in 17 elements of malignant social psychology that nurses and other practitioners should seek to eradicate from practice (Box 2).
Box2. Elements of malignant social psychology (Kitwood, 1999)
Key elements in the person-centred approach include valuing and respecting individuals and giving consideration to her or his perspective. Conditions for successfully implementing this approach include congruence (genuineness), unconditional positive regard and an empathic understanding. 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;
- Within a wider society and its values.
The lack of evidence supporting many of these theories makes them easy to criticise. Adams (1996) and Kitwood (1990) acknowledged that his methods may seem highly subjective and undisciplined. Although his ideas have great appeal for and a potentially inspiring effect on nurses caring for patients with dementia, the lack of supporting empirical evidence weakens their justification. However, that does not prevent Kitwood’s theories having a positive influence on practice. The humanistic approaches, methodology and principles underpinning Dementia-Care Mapping, personhood and malignant social psychology do inform patient-centred methods, which can be adapted and employed when assessing cognitive functioning in people with Alzheimer’s disease.
If care and rehabilitation programmes are to be effective it is essential to ascertain which 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 that identify patients at high risk of a condition such as Alzheimer’s disease (Sood et al, 2004). Repeated testing is also important to monitor change.
There are currently 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 (Dewing, 1999; Kitwood, 1999). Baseline knowledge of the patient as an individual provides a useful background for a more person-centred approach and the nurse or clinician should review the patient’s history before testing by accessing case notes, talking to relatives, carers and other professionals as well as the patient.
During the test, if a patient does not appear 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 when performing testing and interpreting results.
Neuropsychological assessment of cognitive loss (Box 3) can be a distressing and possibly degrading process (Keady and Gilliard, 1999). Practitioners must not discriminate against people with cognitive impairments and equally they must not patronise older people (Dewing, 2003). Communication can be enhanced through taking a friendly, interested and warm approach, speaking slowly and clearly and explaining things while remaining aware of tone of voice and non-verbal aspects such as eye-contact, posture and gesture.
Patients should be informed that they are going to be asked a few questions and that they give the best possible answers before testing begins, and that some questions will be easier than others - with apologies in advance for the fact that some may seem patronisingly easy.
Box3: Patients’ perceptions of the neuropsychological assessment (Keady and Gilliard, 1999)
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 commencing by asking a few basic questions (Box 4) and acting on any problems where conditions will allow by providing larger text and graphics, more ergonomic, easier to grasp and manipulate writing or drawing implements. This will ensure that inability to perform an activity due to physical incapacity does not affect the patient’s test score.
Box4. Questions to establish physical functioning
The time of day when testing takes place 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, therefore be wise to undertake cognitive screening in the morning. However, whatever the time of day the test is performed, repeat testing should be carried out as close to that initial time as possible to ensure a level of consistency and enable more accurate ongoing monitoring of cognitive function.
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 in many cases. To an increasing extent, 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 or perfect. Although the validity of the widely recommended and utilised MMSE has been questioned, it remains the tool most widely used by psychiatric nurses and other clinicians involved in caring for older people with Alzheimer’s disease.
Assessing and treating the individual-specific effects of Alzheimer’s disease combined with physical and psychosocial symptom presentation represents a major challenge for healthcare teams and services. It is not enough to simply perform cognitive testing in a purely clinical or arbitrary way. Attention must be paid to patients as individuals and approaches to cognitive testing should take this into consideration. Box 5 summarises best practice in undertaking cognitive tests.
Before the test
Box5. Summary of best practice
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