Neuropsychological Assessment

NP Ax is used in diagnosis of conditions with cognitive manifestations (e.g. AD). It can be sensitive to abnormalities not detected by neuroimaging. It can can determine the cognitive effects of different disorders (TBI etc.).

NP Ax can establish a baseline to compare future scores in degenerative conditions. It can also establish rate of improvement of cognition after TBI or treatment. Repeated testing can identify changes due to an intervention.

By using NP Ax to establish strenghts and weaknesses, this can guide choice of treatment.

NP Ax assumes that:

• Brain dysfunction can affect behaviour
• Behaviour changes can be associated with brain areas/ processes
• Assessment can be reliable and valid
• Assessment affects diagnosis and treatment

Watt & Crowe (2017) found that NP Ax can increase diagnostic accuracy, can predict outcomes and response to treatment, and can help predict future impairment.

Pre-assessment information from referral and medical history is obtained.

The clinical interview should be shaped towards uncovering relevant elements of the history, including medical history and psychosocial factors.

Collateral, behavioural information from people who know the patient well and observations from other staff (in inpatient cases) can add to your own behavioural observations.

Neuropsychometrics tests can also help.

Strengths

• Generally good reliability (inter-rater, test-retest and internal) and validity (criterion, construct, discriminant and predictive).
• Good at identifying a disorder when presentation is "normal," e.g. MCI.
• Can help to discriminate between disorders (AD vs VaD).
• Fairly good ecological validity - can predict ADLs.

Limitations

• Can be very time intensive (2-8 hours) and administrators need special training.
• Can be moderately expensive compared to other diagnostic measures.
• Practice effects can be present and there are limited forms of other tests.

Important in the initial examination to establish a baseline.

Standardised tests are more reliable and so we can trust the numbers. In medicolegal, non-standard procedures are harder to justify in court unless there is explicit reasoning for using them.

A test is standardised when it satisfies three of the following:

• Readily available and adequately normed
• Test stimulus and materials must be standardised with an informative manual, including information on reliability/ validity
• Research must be published in peer-reviewed journals
• The test has been reviewed in neuropsychology texts by independent parties

Four levels of experimental tests from 1 (never peer-reviewed or published) to 4 (not yet recognised but has prelim normative data and has been peer-reviewed).

Findings from experimental tests should only be used to add to standardised findings, as experiemental tests might have ethical issues.

Bush (2018) found that new tests/ updated versions of old tests do not make current tests obsolete, and continued use of old tests is not unethical. It is reasonable to delay the adoption of new tests until there is sufficient evidence in support.