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Neuropsychological assessments

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30th Jul 2013

THIS Update looks at neuropsychological assessments and the differences between clinical psychologists and clinical neuropsychologists.

Prof Jane L. Mathias  BA, BA (Hons), PhD, MAPS, APS-CCN (Academic Member)

School of Psychology, University of Adelaide, South Australia

Dr Linley A. Denson  BA (Hons), Dip App Psych, M Psych, PhD, MBPsS, FAPS, APS-CCN (Member), APS-CCP (Member)

School of Psychology, University of Adelaide, South Australia

Conflicts: Nothing to declare

Who conducts neuropsychological assessments and what are their skills?

Neuropsychological assessments are usually completed by clinical neuropsychologists, who are registered psychologists that additionally hold specialist endorsement in clinical neuropsychology through the Psychology Board of the Australian Health Practitioner Regulation Agency (AHPRA).

Although all registered psychologists are able to perform cognitive assessments, clinical neuropsychologists are better qualified to perform detailed neuropsychological assessments because they have specialist postgraduate training in the assessment, treatment and rehabilitation of people with known or suspected brain impairments.

Clinical neuropsychologists have master’s or doctoral level tertiary qualifications specialising in the clinical implications of the different types of brain dysfunction that can occur throughout the lifespan. Clinical psychologists, on the other hand, focus more on the assessment and treatment of emotional and behavioural problems. Both are required to participate in ongoing professional development activities in order to maintain their specialist endorsements.

Table 1 summarises the different qualifications, training, roles, and funding and rebate options for clinical neuropsychologists and clinical psychologists in order to highlight the differences between these two specialties.

What is a neuropsychological assessment?

Neuropsychological assessments are designed to provide a detailed evaluation of a person’s cognitive abilities in situations where it is either known or suspected that a person has some form of brain damage or dysfunction. They complement the assessments completed by paediatricians, physicians, neurologists, psychiatrists, geriatricians and neuroradiologists.

Neuropsychological assessments identify, measure and describe the changes to cognition and behaviour that occur as a result of any form of brain impairment, while also taking into consideration a range of psychological (e.g. anxiety and depression), medical (e.g. medications, comorbidities), sociodemographic (e.g. premorbid cognitive ability, educational attainment), and other (e.g. eligibility for compensation, disingenuous performance) factors that may impact on test performance.

Neuropsychologists see people who have a wide variety of conditions, the most common of which are summarised in Table 2, and frequently perform an assessment to assist with:

  • diagnosing neurological disorders, differential diagnoses, and establishing prognoses
  • determining a person’s need for care/ support services by evaluating whether he or she:
  •  
    • is capable of living independently and any supports that may be needed to maintain independence
    • is able to return to work or study and in what capacity
    • has the cognitive abilities needed to retain a driver’s licence or manage his or her financial affairs
    • has insight into his/her limitations
  • documenting functional decline in the early stages of a disorder, particularly in cases where other investigations have proven negative or inconclusive
  • the development of cognitive strategies to maximise functioning in persons who are cognitively compromised
  • monitoring change: after an acute neurological event (e.g. stroke, traumatic brain injury, carbon monoxide poisoning), due to a degenerative neurological disorder (e.g. Alzheimer’s disease, multiple sclerosis), or following brain surgery (e.g. for intractable epilepsy, to remove a tumour, or insertion of a neurostimulator for Parkinson’s disease).

Whereas many allied health assessments focus on everyday function and activities of daily living, neuropsychologists use standardised psychometric testing to formally assess and document any changes to cognition and behaviour caused by brain impairments.

Where needed, these assessments provide an additional resource for good practice by providing an objective answer to difficult questions — questions that require more time and more detailed testing than a routine consultation or screening measure can provide in a general practice setting.

Equally, neuropsychologists can assist where there are reports of cognitive or behavioural dysfunction and an underlying brain disorder is suspected.

Formal cognitive assessment can usually identify subtle but disabling problems earlier than brain imaging can, thereby facilitating early intervention and reducing the distress experienced by patients and their families. This may be helpful, for example, when dealing with forgetfulness in older patients, traumatic brain injury in young adults, and attentional or learning issues in children.

Other scenarios in general practice where a neuropsychological assessment may prove informative are outlined in Table 3.

Referral process

A GP can arrange a neuropsychological assessment by providing a written referral in which the patient’s history is summarised and a specific referral question is posed. Neuropsychologists generally also welcome the chance to discuss a patient by phone, either before or after an assessment.

Time and cost involved

Neuropsychological assessments vary in length depending on their purpose, but generally take 3—8 hours, which may be split over multiple sessions. This time is needed to perform a detailed clinical interview and history-taking, and to administer cognitive tests and self-report questionnaires, after which time is needed to score and interpret the results. Ideally, a close relative or friend will accompany the patient and be interviewed by the neuropsychologist to confirm historical details and obtain additional information and observations regarding the patient’s cognitive, emotional and behavioural problems.

Depending on the length of the consultation and report, a private assessment may cost the patient about $1000. Some private health funds provide partial reimbursement for an assessment. The Department of Veterans’ Affairs and relevant state WorkCover/WorkSafe agencies and motor/traffic accident commissions may also fully fund private assessments for eligible clients.

Unfortunately, there is currently no Medicare rebate for this service, as existing Medicare psychology items apply strictly to the assessment and treatment of mental health conditions and cannot be used to support the assessment or rehabilitation of neuropsychological conditions. Bardenhagen (2012)1 provides a more detailed summary of the background to these funding issues.

In the public sector, some hospitals accept GP referrals for outpatient assessments of children and adults, but waiting lists for these services are often long. Alternatively, if dementia is suspected, it may be appropriate to refer middle-aged and older patients to memory clinics, which are located in some of the larger public hospitals.

What is assessed?

Clinical neuropsychologists assess a number of different cognitive functions, in addition to examining a range of variables that may impact on test performance. There is no single standard for conducting a neuropsychological assessment; consequently they differ between clinical neuropsychologists, clients and referral questions.2 More particularly, clinicians may differ in the tests they use, although various surveys completed in Australia and overseas indicate that there is considerable overlap in the measures that are most frequently used.3-6

Some clinical neuropsychologists choose scales that contain a range of subtests, such as the Wechsler scales (Wechsler Adult Intelligence Scale, Wechsler Memory Scale), and base their conclusions on empirically derived scores that measure a person’s level of functioning in a variety of core cognitive domains (e.g. working memory, processing speed, perceptual reasoning, verbal comprehension).

Other neuropsychologists select a range of validated individual tests that are designed to measure a variety of cognitive functions, such as motor skills, processing speed, orientation, attention, perception, memory and learning, verbal skills, visuospatial skills, executive functioning, and general academic abilities. Still others supplement the Wechsler scales with tests of specific abilities to enhance their evaluation. Table 4 summarises the main cognitive abilities that are assessed, together with some of the specific cognitive functions that may be evaluated.

Neuropsychological assessments frequently also involve evaluating a range of other variables that may impact on a person’s cognitive performance (e.g. mood) and enable them to gauge how well the person is functioning in their normal daily activities.

In addition, they routinely use measures to estimate a person’s premorbid level of cognitive functioning and, when financial compensation or other secondary gains are an issue, they also use tests to evaluate whether the person was performing to the best of their ability (test effort) and, therefore, whether the results of the neuropsychological assessment are likely to provide a valid measure of their cognitive abilities.

The exact choice and range of tests will depend on a variety of factors, including the referral question; the patient’s age, education and intellectual ability level; their sensory and motor abilities; their language and cultural background; their level of compliance and motivation; and other issues that may emerge during testing.

There are some patients who might not be suitable for neuropsychological assessment (e.g. those who are in an acute delirium or psychotic state, or who have a severe receptive communication deficit).

Many variables can independently affect a person’s test performance, including motivation, depression, anxiety, sensory and motor disabilities, pre-existing learning problems, other medical conditions, medications, and substance abuse, as well as a variety of sociodemographic variables, such as age, language (e.g. when English is a second language) and cultural background.

The formal testing process assumes that patients are alert, motivated and able to perform to the best of their abilities, have average reading abilities and manual dexterity, and have good (corrected) vision and hearing. If any of these factors are likely to be an issue, it may be useful to speak with the neuropsychologist before making a referral.

It is also important to routinely provide details of other medical investigations and diagnoses, brain imaging, current medications, and any sensory, motor, language or cultural issues that you believe might impact on a cognitive assessment; thereby assisting the neuropsychologist to determine the need for alternative non-standard tests that may be more suited to these circumstances.

Determining deficits

Once a person has undergone formal cognitive testing, it is necessary for the neuropsychologist to determine whether the test performance is impaired or not. This is achieved by comparing the person’s performance with the population norms for a test, while also taking into consideration the person’s estimated (premorbid) cognitive ability.

Test norms are derived from a healthy sample that has been tested on a measure in order to determine what can be regarded as average or ‘normal’ performance. The normative sample should match the client in terms of important variables, such as age and education, which may independently affect test performance. Test norms allow a clinical neuropsychologist to determine whether a person is performing above or below average. However, they often do not take into consideration a person’s previous or premorbid level of functioning. Thus, a person may be performing within normal limits for the general population but, if they were previously of above-average ability or were highly educated, their current performance may reflect deterioration from previous levels.

A person’s underlying level of cognitive ability is therefore also frequently estimated in order to provide a more individualised method by which to evaluate their performance. This may involve accessing the results of a previous cognitive assessment, if one has been performed, or assessing individuals on multiple occasions and comparing their later performance to their baseline assessment (e.g. pre- and post-surgery; or when problems are first suspected versus 6—12 months later). Neuropsychologists also estimate a person’s level of premorbid cognitive ability using historical data (e.g. education, occupation) and demographic information, which can be used to provide a broad estimate of a person’s premorbid intellectual functioning, as these variables account for a large proportion of the variance in intellectual ability (IQ scores).

Alternatively, some skills are relatively resistant to the effects of brain damage and ageing (e.g word knowledge); tests of these skills are used to estimate premorbid IQ and provide a benchmark against which current performance can be compared. In addition, demographic information can be combined with tests of premorbid intellectual ability to improve the reliability of the estimate.

Reporting the findings

The clinical neuropsychologist will send the referring GP a written report summarising their assessment, opinion and recommendations. This may or may not include test scores but will include an evaluation of the person’s performance in each of the cognitive domains that were assessed, together with any other information that was collected. They may also offer the patient and family a feedback session, or the GP may provide feedback on the assessment findings themselves.

Finding a clinical neuropsychologist

To locate a clinical neuropsychologist, contact your state section of the Australian Psychological Society (APS) College of Clinical Neuropsychologists (CCN) (http://www.groups.psychology.org.au/ccn/state) or phone the nearest teaching hospital, which is likely to have a neuropsychologist on staff.

The hospital neuropsychologist will be happy to discuss referral options and can also provide contact details for the nearest local services: public or private. Almost all of Australia’s 450 neuropsychologists live and work in major cities and towns, consequently there are few local services in remote areas, apart from visiting (fly-in, fly-out) clinicians.

Neuropsychologists can also be found by checking the APS’s ‘Find a Psychologist’ service (www.psychology.org.au/FindaPsychologist) or the phone directory (under ‘Psychologists’).

References:

Bardenhagen, F. (2012). Dementia spending: Missing early diagnosis and treatment planning. Hospital and Aged Care, 1 August 2012, pages 20-23. http://www.hospitalandagedcare.com.au/news/dementia-spending-missing-early-diagnosis-and-treatment-planning1

Crowe, S. F. (2010). Evidence of absence. A guide to cognitive assessment in Australia. Queensland: Australian Academic Press.

Lees-Haley, P. R., Smith, H.H., Williams, C.W. & Dunn, J.T. (1996) Forensic neuropsychological test usage: An empirical survey. Archives of Clinical Neuropsychology, 11 (1), 45-51

Mullaly, E., G. Kinsella, et al. (2007). “Assessment of decision-making capacity: Exploration of common practices among neuropsychologists.” Australian Psychologist 42(3): 178-186.

Rabin, L. A., Barr, W. B., & Burton, L .A (2005). Assessment practices of clinical neuropsychologists in the United States and Canada: A survey of INS, NAN, and APA Division 40 members, Archives of Clinical Neuropsychology, 20 (1), 33-65.

Sullivan, K. C. & Bowden, S. C. (2007). Which tests do neuropsychologists use? Journal of Clinical Psychology, 53 (7), 657-661.

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