Background
The abolition of fixed retirement means that many people will work into their late 60s or even their early 70s. Older health care workers tend to suffer from the four Ds—drink, drugs, depression and dementia [1]. Studies show negative correlations between performance on cognitive testing and job performance problems [2] or with age [3]. One study found cognitive impairment in doctors was responsible for 63% of all adverse medical events with most being preventable [4].
A BRIEF GUIDE TO COGNITIVE IMPAIRMENT SCREENING AND ASSESSMENT TOOLS. Brief neuropsychological. Cognitive dysfunction in multiple sclerosis. Central nervous system, cognition, cognitive test. Component Tests Cognitive Domain Assessed Brief Repeatable.
Detection of cognitive impairment is essential in determining any risk to patient safety and to safeguard patients by designing and implementing effective remediation programmes. Dementia UK [5] estimates that 1.3% of people aged 65–69 years have dementia rising to 2.9% for those aged 70–74 years. Lesser degrees of cognitive impairment can be more common in people at these ages, increasing demand on occupational physicians to assess older workers for possible cognitive impairment(s). Mild cognitive impairment converts to dementia at a rate of ~10% per year [6], a clinical challenge due to the variety and often dynamic nature of symptoms.
There is need to determine whether cognitive impairment is present but also to establish which cognitive domains are affected in relation to skills and knowledge required by the person’s occupation [7]. Screening must be effective, cost beneficial with suitable methods and therapeutic evidence. Patients may perform poorly on formal cognitive tests for other reasons, including acute illness, pain, lethargy, sleep deprivation, medication, depression, anxiety, not wishing to engage with testing, language barriers, cultural issues and learning disability. Hence these tests form part of the overall clinical assessment and clarity is needed as to the level of detail required for screening, differential diagnosis or detailed neuropsychological analysis.
Brief history
The original Addenbrooke’s Cognitive Examination (ACE) was developed in the Medical Research Council Cognition and Brain Sciences Unit in Cambridge in the late 1990s as a simple bedside test battery designed to detect mild dementia and differentiate Alzheimer’s disease from frontotemporal dementia [8]. The diagnostic accuracy of ACE as a brief ‘bedside’ cognitive screening instrument led to its widespread adoption. The original ACE included the mini-mental state examination (MMSE) or Folstein test, along with fronto-executive and extra visuospatial items. However, weaknesses were identified in the ACE, which prompted the development of the Addenbrooke’s Cognitive Examination-Revised (ACE-R) to facilitate cross-cultural usage and improve sensitivity. The original 26 components were combined to produce five subscores, each representing a specific cognitive domain: attention/orientation (18 points), memory (26 points), fluency (14 points), language (26 points) and visuospatial function (16 points)—100 in total. It gives a cut-off score for the five subdomains against controls and takes between 12 and 20min (average 16). The ACE-R sensitivity to mild dementia (84–94% depending on cut-off point) is better than the MMSE [9]. Three different alternative versions—A, B and C, with different stimuli for the name and address recall—prevent recalling from administration of previous tests. One cognitive domain that was not well covered by the ACE-R, but which is important in many occupations, is termed fluid intelligence, key to problem solving. There are tests of fluid intelligence, but these generally are the preserve of neuropsychologists [7]. A review of the diagnostic accuracy of ACE and ACE-R found that ACE-R had somewhat superior diagnostic accuracy to the MMSE while ACE had less. Hence, the ACE-R was recommended in both moderate dementia (primary care and general hospital settings) and high dementia prevalence settings (memory clinics) [10]. Despite the wide use of ACE-R, the cognitive domains of the test have not been validated against standard neuropsychological tests.
In light of weaknesses of certain domains in ACE-R, such as repetition, comprehension, visuospatial, items on the ACE-R were replaced to form the ACE-III. Failure on the verbal repetition item (‘no ifs, ands or buts’), for example, is often seen in healthy adults [11], which could be related to poor hearing or attention. Translation of this item is also known to be difficult [12]. Measures of comprehension (such as the three-stage command and ‘close your eyes’) lack sensitivity to cognitive impairment as impaired individuals can often perform to normal limits [13]. Spelling of the word ‘WORLD’ backwards is substituted with failure on serial 7s. These two items, however, correlate modestly and are known to differ in item difficulty [14]. In light of these weaknesses, items on the ACE-R were replaced to form the ACE-III, which continues to be scored out of 100 and contain five cognitive domains but it is no longer possible to derive the MMSE score [15].
Comparison with other tests and previous versions
Testing shows that ACE-III cognitive domains correlate significantly with standardized neuropsychological tests used in the assessment of attention, language, verbal memory and visuospatial function. It also compared very favourably with its predecessor, the ACE-R, with similar levels of sensitivity and specificity [16] and the two tests correlated significantly (r = 0.99, P < 0.01). The ACE-III also continues to show high sensitivity and specificity at cut-offs previously recommended: (i) 88 (sensitivity = 1.0; specificity = 0.96) and (ii) 82 (sensitivity = 0.93; specificity = 1.0). Internal reliability of the ACE-III, measured by Cronbach’s α coefficient, was 0.88.
Administration
The assessment focuses on five cognitive domains:
Attention
Memory
Verbal fluency
Language
Visuospatial abilities
Within the attention domain, subtraction of serial 7s from 100 is no longer substituted by spelling of ‘WORLD’ backwards. In the language section, the three-step command is replaced by three single-step commands, which increase in syntactical complexity. Comprehension of the written command (‘close your eyes’) was removed. The sentence-writing task was modified: participants are asked to write two or more sentences about a single topic with a maximum score of 2 points. Two common proverbs replace the phrase repetition items. Naming of the two easiest items (‘pencil’ and ‘watch’) is replaced by other highly familiar objects (‘spoon’ and ‘book’). In the visuospatial section, overlapping infinity loops replace the intersecting pentagons. The memory and fluency domains, which were in the ACE-R, were not modified.
It takes 15–20min to administer and score. The cut-off for dementia [17] is 82–88/100. One disadvantage is that it does not specifically test reasoning and judgement [18]. Some training is needed for administration and becoming familiar with the instrument. Normally this takes a few hours.
Access
The ACE-III is available for free. The copyright is held by Professor John Hodges who is happy for the test to be used in clinical practice and research projects. The ACE-III scoring and administration guidelines can be obtained at the following website: http://www.neura.edu.au/frontier/research/test-downloads/.
References
Brief Cognitive Assessment Pdf
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