Screening for cognitive impairment

Things to consider when screening for cognitive impairment

Screening for dementia is not recommended for the general population as there are no screening tests which can diagnose dementia before symptoms develop and because there is no evidence that current treatments are effective in early dementia.¹ There are also concerns about the potential impact of early diagnosis on patients. There are calls from some clinicians in the USA to consider screening in certain groups.²

However, healthcare professionals should be aware of clinical features that may suggest cognitive impairment and should also be aware of the risk factors of dementia in people with conditions such as Down syndrome and other learning disabilities, after a stroke, and in Parkinson's disease.³ General practitioners need to be able to recognise cognitive impairment and possible dementia using:

• History taking.

• Cognitive and mental state examination.

• Physical examination and other appropriate investigations.

• A review of medication in order to identify and minimise use of drugs, including over-the-counter products, which may adversely affect cognitive functioning.

See the separate Dementia and Supporting the family of people with dementia articles.

The rest of this article deals with the screening tests that can be used to detect cognitive impairment. The limitation of such cognitive function tests should be recognised. Previous UK studies found that increased use of the tests was not reflected in an increase in the hospital diagnosis of dementia.⁴ More recent studies suggest that some cognitive function tests are more effective than others.⁵

Tests for cognitive impairment can detect dementia but there is no strong evidence whether interventions for patients or their carers have a clinically significant effect for people with cognitive impairment detected earlier. Medication is now available but the evidence for benefit is very limited.⁶ Pharmacological treatments have high costs, potential side effects. and very modest evidence of success in slowing the symptoms of dementia. ⁷ Early diagnosis allows the person to plan ahead while they still have the capacity to make decisions about their future care, make legal and financial decisions, and enables the person and their family members to receive timely practical information, advice, and support. It may also result in relief that there is an explanation for their symptoms. However, it can also result in anxiety, depression, and withdrawal from family and friends. It may also add to caregiver burden earlier than would otherwise be the case.⁷

Clinical assessment for cognitive impairment

• Clinical cognitive function tests in those with suspected dementia should include examination of attention and concentration, orientation, short-term and long-term memory, praxis, language, and executive function.

• As part of this assessment, formal cognitive testing should be undertaken using a standardised instrument. For the purposes of screening in primary care, a test should be short, simple and easy to learn, and perform with high sensitivities and specificities.

• Those interpreting the scores of such tests should take full account of other factors known to affect performance, including educational level, skills, previous level of functioning and attainment, language, and any sensory impairments, psychiatric illness, or physical/neurological problems.

• Formal neuropsychological testing should form part of the assessment in cases of mild or questionable dementia. Many of the standard cognitive tests are designed for measuring impairment in older adults of average ability, whose cognitive abilities are generally slightly different in range and strength from those under 65 years. In the case of younger people, a review by a specialist Cognitive Neurology team or a Clinical Neuropsychologist is required, as they have the tools to make diagnoses that may be missed by standard test protocols. In most areas of the UK, memory clinics will only see patients above the age of 64, whilst younger patients would need a referral to a neurologist.

• At the time of diagnosis of dementia and at regular intervals subsequently, assessment should be made for medical comorbidities and key psychiatric features associated with dementia, including depression and psychosis, to ensure optimal management of co-existing conditions.

The General Practitioner Assessment of Cognition (GPCOG)

The GPCOG consists of cognitive function test items in addition to historical questions asked of an informant. It is faster to administer than the MMSE and has been shown to be similarly effective.⁸⁹

The Mini Mental State Examination

The MMSE was developed by psychiatrists and has long been highly regarded. It is copyrighted and cannot be used without permission. Recent studies suggest it performs moderately against other tests⁵ and may be particularly less effective in diagnosing mild cognitive impairment.¹⁰

The Six-item Cognitive Impairment Test (6CIT)

The 6CIT is a newer cognitive function test than others but appears to have good sensitivity but reduced specificity compared with others. The National Institute for Health and Care Excellence (NICE) recommends it as one of the validated tests for use in a non-specialist setting.¹¹

Addenbrooke's Cognitive Examination III (ACE-III)

Developed in 2013, the ACE-III looks at a wider number of cognitive functions than some of the other tests. Although it is influenced by demographic variables, such as age, intelligence, and education, ¹² it has been shown to be the most effective test when compared with others.⁵It takes longer than other tests but the M-ACE has been developed as a faster screening tool.

Mini-Addenbrooke's Cognitive Examination (M-ACE)

Developed in 2015, the M-ACE appears to be very sensitive for diagnosing probable dementia.¹³It performs better than other screening tests on direct comparison.⁵

Abbreviated Mental Test (AMT)

The AMT is a quick-to-use screening test that was first introduced in 1972 but is less widely used today. Its disadvantages are the ability to be confounded by intelligence, age, social class, sensitivity of hearing, and history of stroke. Some of its questions are beginning to become less effective due to the passage of time and there is a suggestion that it will need updating.¹⁴

Test Your Memory (TYM) Test¹⁵

TYM can be a useful self-administered test. It is advocated by NICE as a validated test suitable to be used in a non-specialist setting.¹¹ The test involves:

• Orientation.

• Ability to copy a sentence.

• Semantic knowledge.

• Calculation.

• Verbal fluency.

• Similarities.

• Naming.

• Visuospatial abilities.

• Recall of a copied sentence.

The ability to do the test is also scored.

Other tests recommended by NICE¹¹

These include:

The 10-point cognitive screener (10-CS)

• The 10-CS involves three temporal orientation questions (year, month, date), a three-word recall, and a four-point scaled animal naming task.

• One point is scored for each of the temporal questions and each word recalled, and the scores for the animal naming task range from 0 points for 0-5 animals, to four points for 15 or more animals.

• A score of eight or more is normal, 6-7 suggests possible cognitive impairment, and 0-5 suggests probable cognitive impairment.

6-item Screener

• This is comprised of three temporal orientation questions (year, month, day of the week) and a three-word recall.

• Each correct response scores one point for a total maximum of six points.

• Two or more errors are considered high risk for cognitive impairment.

Memory Impairment Screen (MIS)

• At the beginning of the assessment the person is shown four words. The person is then given a category and requested to identify which word fits into that category. This is completed for all four words and it is explained that they will be asked to remember the words in a few minutes. A distractor activity is performed for two or three minutes (for example, counting to 20 and back, counting back from 100 by 7, spelling the word 'world' backwards) and then the person is asked to recall the four words.

• The maximum score is 8 (two points for each word recalled without prompting and one point for each word that requires prompting). A score of 5-8 indicates no cognitive impairment, and a score of 4 or less indicates possible cognitive impairment.

Mini-Cog Test

• This consists of two components: a three-item recall test for memory and a clock drawing test.

• There is one point for each word remembered after the clock has been drawn, and two points for a normal clock.

• A total score of 3, 4, or 5 indicates lower likelihood of dementia but does not rule out some degree of cognitive impairment.