Screening for Cognitive Impairment

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, that may adversely affect cognitive functioning.

People who are assessed for the possibility of dementia should be asked if they wish to know the diagnosis and with whom this should be shared.

• Clinical cognitive assessment 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, 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.
• 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 coexisting conditions.

The General Practitioner Assessment of Cognition (GPCOG)

The GPCOG consists of cognitive test items in addition to historical questions asked of an informant (see GPCOG calculator record). It has been found to be reliable and superior to the Abbreviated Mental Test (AMT), and possibly to the Mini Mental State Examination (MMSE), in detecting dementia.^1,2 The two-stage method of administering the GPCOG had a sensitivity of 0.85 and a specificity of 0.86.³ Patient interviews took less than 4 minutes to administer and informant interviews less than 2 minutes.

The Mini Mental State Examination

The MMSE was developed by psychiatrists and is widely regarded as the 'gold standard' test for dementia. See separate article on Mini Mental State Examination.

The 6 Item Cognitive Impairment Test (6CIT)

Developed in 1983, the 6CIT is relatively unknown, although because of recognition by The Royal College of General Practitioners together with new computerised versions, its usage is increasing.

The 6CIT is a much newer test than the AMT (see below) and it would appear to be culturally and linguistically translatable with good probability statistics; however, it is held back by its more complex scoring system. It would be reassuring to see some additional larger population studies using the test.

Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)

When combined with cognitive tests, such as the MMSE, the IQCODE provides a useful overview and hence sensitivity and specificity as a screening test can be improved.⁴

The questionnaire asks how the patient compares today with 10 years ago in various activities, e.g. remembering birthdays and recalling conversations.

Abbreviated Mental Test

The AMT is a quick to use screening test that was first introduced in 1972. Developed by geriatricians, this is probably the best known test in general hospital usage; however, it lacks validation in primary care and screening populations.

Its disadvantages are the ability to be confounded by intelligence, age, social class, sensitivity of hearing and history of stroke.^5,6

• Patients identified on screening should be further investigated to exclude reversible causes of memory loss and to try and establish a pattern to the memory loss that might point you towards the cause.
• Remember depression commonly presents with memory loss as a symptom and thus it would be sensible to screen for this prior to referral.
• Depression scores, such as the 4 item Geriatric Depression Score, are easy and quick to perform with a high sensitivity and specificity. Patients who screen positive for depression should be treated with antidepressants and be reassessed cognitively when their depression has lifted. Care must be taken as dementia and depression often co-exist.

Routine investigations

These should also include:⁷

• Full blood count
• Erythrocyte sedimentation rate
• Urea and electrolytes
• Glucose
• Liver function tests (including gamma glutamyl transferase) and calcium
• Thyroid function tests
• MSU (if delirium is a possibility)
• B12 and folate (red cell folate)

Consider also doing the following in relevant groups of patients:

• HIV, syphilis screen, drug screen, monitor blood levels of certain drugs (e.g. anticonvulsants or digoxin).
• Consider blood cultures and CT/MRI scan (to exclude subdural or space occupying lesion).

• All patients who screen positive should be referred, except where a reversible cause has been identified and subsequent cognitive screening has then been negative (it may be prudent to recall these patients annually for repeat testing).
• Most research confirms that early diagnosis is extremely important in order to attempt to arrest progression of the disease. Research confirms that early intervention with measures as simple as patient support and counselling may delay admission to residential care by up to 1 year. This effect is not seen where a delay of as little as 6 months between identification and treatment exists.

• Patients should ideally be referred to a memory clinic where psychologists will be available to perform detailed cognitive testing to determine whether or not they have a dementia.
• Where a memory clinic does not exist the patient should be referred to a geriatric psychiatrist with a request for neuro-psychological testing. (Neurologists and geriatricians do not have access to the community mental health teams that are necessary to provide adequate care).