Cognitive screening tests
A full neuropsychological evaluation of a client is not always possible. Cognitive screening tests can be a useful alternative option.
Advantages and limitations of screening tests
Because of the time and financial costs of neuropsychological assessment, it's not always practical or necessary to have a person who is thought to have a cognitive impairment referred to a neuropsychologist for a full neuropsychological evaluation.
There's been a prolific development of cognitive screening tests since the middle of the 20th century due to a recognised need to identify cognitive impairment, mainly for primary care clinicians and mainly for the purpose of assisting with the diagnosis of dementia in the elderly.
There are a number of advantages to using cognitive screening tests:
- They can identify those with cognitive impairment.
- They can identify, at a broad level, cognitive strengths and weaknesses.
- Due to their brevity and simplicity, they are relatively non-demanding for the client.
- They are portable.
- They can assist with management and/or treatment of cognitive impairment.
- They allow a tailored approach to treatment.
- They promote education of the client and their carer/family about their condition.
- Most require no specialised qualifications for administration and require little formal training for appropriate scoring and administration.
- They're not as time consuming, costly or imposing as a full neuropsychological assessment (administration time varies from 5 to 30 minutes).
- They help identify those in need of more detailed neuropsychological investigation.
- Objectivity and quantification allow for comparison between time points.
- They can be used to monitor improvement where this is expected (e.g. with abstinence) or decline where it is suspected (e.g. alcoholic dementia).
There are also limitations to using cognitive screening tests:
- Poor sensitivity (see 'psychometric properties' below) - they may miss some individuals with cognitive impairment.
- Poor specificity (see 'psychometric properties' below) - they may falsely detect cognitive impairment when there is none.
- Brevity usually compromises reliability.
- Incorrect administration and scoring can significantly skew results.
- Single items or domains are often not very reliable, so are not a good indicator of true strengths and weaknesses.
- Not all domains are assessed in screening tests (e.g. visual memory and executive functioning are not typically covered).
- They often miss non-verbal impairments as most measures are highly verbally loaded.
- They're not good at detecting impairment in previously high-functioning and/or well-educated people.
- They may produce false positive errors in cases of those with:
- Culturally and linguistically diverse background
- Low education
- Poor literacy
- Low intellect, and
- Poor motivation/lack of cooperation.
- There's limited generalisability beyond the population for which the tool was developed (e.g. if a tool was developed to detect impairment in dementia, it won't necessarily detect impairment in a drug and alcohol population).
- Lack of sensitivity to executive dysfunction - this is an important limitation because executive dysfunction is common in a range of conditions, including non-Alzheimer's dementias (e.g. vascular dementia, fronto-temporal dementia), traumatic brain injury, stroke, Parkinson's disease, schizophrenia, and alcohol and other drug related brain impairment.
Reliability and validity of screening tests
A test's reliability and validity are referred to as its 'psychometric properties'. Reliability refers to the stability of test scores and includes test-retest reliability (the probability of getting the same or similar score at two points in time) and inter-rater reliability (the probability of two examiners independently arriving at the same score). Validity refers to whether a test measures what it's supposed to measure and includes face validity (whether the test appears to measure what it's supposed to) and criterion-related validity (whether the test performs similarly to a gold standard, such as neuropsychological assessment).
In general, the greater the length of a cognitive screening measure and the simpler the administration and scoring, the better the reliability. A valid test has high sensitivity (detects impairment when it's present) and specificity (detects normality when it's present). Generally, the greater the sensitivity the less the specificity, and vice-versa. Cognitive screening measures have lower sensitivity and specificity than neuropsychological assessment when it comes to detecting presence or absence of cognitive impairment.
The psychometric properties of a test refer to the test’s reliability and validity. Reliability refers to the stability of test scores and includes test-retest reliability (the probability of getting the same or similar score at two points in time) and inter-rater reliability (the probability of two examiners independently arriving at the same score). Validity refers to whether a test measures what it’s supposed to measure and includes face validity (whether the test appears to measure what it’s supposed to) and criterion-related validity (whether the test performs similarly to a gold standard, such as neuropsychological assessment).
In general, the greater the length of a cognitive screening measure and the simpler the administration and scoring, the better the reliability. A valid test has high sensitivity (detects impairment when it’s present) and specificity (detects normality when it’s present). Generally, the greater the sensitivity the less the specificity, and vice-versa. Cognitive screening measures have lower sensitivity and specificity than neuropsychological assessment when it comes to detecting presence or absence of cognitive impairment.
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Examples of cognitive screening tests
The following examples have been chosen to demonstrate variability in factors such as administration time, qualifications required, validation in drug and alcohol populations and cost/availability.
The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) has excellent psychometric properties for a screening tool. It includes 12 subtests that factor into five domains: Immediate Memory, Visuo-spatial/Constructional, Language, Attention, and Delayed Memory. There is also a total score. It takes 30 minutes to administer. It includes comprehensive normative data from a large sample, allowing for valid and reliable documentation of cognitive strengths and weaknesses. Some studies have used the RBANS to specifically examine the effect on cognition from substance use disorders (e.g. Green et al 2010). Despite this tool being lengthier than most cognitive screening tools, executive functioning is not adequately sampled; it requires specific user qualifications (allied health or special education professional).The full kit costs in excess of $650 and is available from Pearson PsychCorp (www.pearsonpsychcorp.com.au).
The Addenbrooke's Cognitive Examination - III (ACE-III) comprises 19 brief subtests that make up five dimensions: Attention, Memory, Fluency, Language, and Visuo-spatial. It takes 15 minutes to administer. Although its predecessor, the ACE - Revised (ACE-R) was originally developed to detect mild cognitive impairment (a precursor to dementia) and rarer forms of dementia such as fronto-temporal dementia, it has shown utility in detecting cognitive impairment in other populations, such as traumatic brain injury (Gaber 2008). The ACE-III has comparable psychometric properties to the ACE-R, which are good for a test of this length. However, it has not been validated specifically in a drug and alcohol use disorder population. There are no qualification restrictions for use of the test. Pending registration, it's available free of charge from www.neura.edu.au/frontier/research/test-downloads/
The Hayes Ability Screening Index (HASI) is a brief, individually administered screening index of cognitive impairment for people between the age of 13 and late adulthood. The HASI was originally designed to support the identification of potential intellectual disability in criminal justice clients to assist in identifying when an individual may be vulnerable and indicate if further support or assessment is required, but the tool has been administered more broadly in the community sector as a screening tool for cognitive impairment. The tool is not culture or gender biased. It takes 5-10 minutes to administer and requires no minimum qualifications, though half-day training is advised. The HASI can be purchased from the University of Sydney Behavioural Sciences in Medicine Department (www.sydney.edu.au/medicine/bsim/hasi/)at $215 for a complete set.
The Montreal Cognitive Assessment (MoCA) comprises eight domains: Visuo-spatial/Executive, Naming, Memory, Attention, Language, Abstraction, Delayed Recall, and Orientation. Administration time is 10 minutes. For a test of its brevity, its psychometric properties are very good. It's more sensitive than the Mini Mental Status Examination (MMSE) at detecting cognitive impairment, although it takes the same length of time to administer. Although the MoCA was originally developed to detect mild cognitive impairment, a precursor to dementia, its inclusion of items sensitive to frontal lobe (executive) impairment has made it attractive across a range of populations, on which it has been validated, including substance use disorders (Copersino et al 2009). There are no qualification restrictions for use of the test. It's available free of charge for non-commercial use from www.mocatest.org. This website also includes information about norms and cut-off scores.Back to top
Although the ACE-III and MoCA do not require specific qualifications for users, familiarisation of the standard administration and scoring procedures is highly recommended. Two-to-three-hour training workshops for these measures are available (e.g. neurotraining.net.au).
The Lyndon Community, a large non-government drug and alcohol treatment service in regional NSW, incorporated the ACE-R into staff training in 2011. The in-house training workbook is available on their website for download at www.lyndoncommunity.org.au/research-training/publications-and-reports.
Because of the brevity of the ACE-III and MoCA, these tools are particularly susceptible to non-specific variables that can potentially significantly skew test results. These include low mood state, reduced motivation, CALD status, history of learning disability and high education level. It's recommended that consultation be sought from a neuropsychologist to assist with interpretation of borderline or unusual results in these cases.
Optimal time to administer cognitive screening tests
In a drug and alcohol service, it's not valid to use these tools during periods of intoxication or withdrawal. As such, a rule of thumb of 2-3 weeks abstinence is optimal. Furthermore, choosing a time of day when the client feels most alert and rested is important.
Tips when conducting an assessment with a person with cognitive impairment:
- Conduct the assessment in person if possible.
- Be aware that a person may need to take breaks during the assessment.
- Address the person directly and use a tone of voice consistent with their age, e.g. speak to an adult as an adult.
- Invite the person to say if they're not sure what you mean, but be aware that, even if you do this, they may not disclose a lack of understanding. You should take responsibility for frequently checking the person's understanding by saying something like "Many people find this information difficult to understand, so can I check that I have explained it clearly?"
- Deal with one question, area or piece of information at a time. Also, 'signpost' when you're about to change conversation topic. For example, say "That's all I need to ask you about ABC. Now I'd like to talk to you about XYZ."
- Ask open questions and encourage the person to respond at their own pace; try not to rush a response or finish their sentences.
- Use plain, everyday language and short, clear sentences and try to minimise use of jargon and abstract concepts.
- Have pictures and visual representations handy to aid in the explanation of assessment questions. If the person agrees they will help, these can be used to aid explanation of concepts.
- People without high verbal skills rely more on body language, so you should be aware of their non-verbal communication such as facial expressions, gesture and posture.
- With the consent of the person, it may be appropriate to involve a family member, carer or support worker during the assessment process.
Find out more
A comprehensive review of cognitive screening tools is beyond the scope of this chapter. For recent reviews see:
- Cullen, B., O'Neill, B., Evans, J., Coen, R. & Lawlor, B. (2007) 'A review of screening tests for cognitive impairment', Journal of Neurology Neurosurgery & Psychiatry, 78, 790-99.
- Ismail, Z., Rajji, T.K. & Shulman, K.I. (2010) 'Brief cognitive screening instruments: An update', International Journal of Geriatric Psychiatry, 25, 111-20.
- NADA (Network of Alcohol and Drug Agencies) (2013b) Brief Guide to Cognitive Impairment Screening and Assessment Tools, NADA: Sydney.