Clinical neuropsychology is a subspecialty of professional psychology that is concerned with the scientific study and clinical application of brain-behavior relationships. Broadly defined, a neuropsychological evaluation is a flexible clinical tool that involves integration of objective, psychometric test data along with various other sources of clinical information to comprehensively elucidate the cognitive, behavioral, and emotional sequelae after traumatic brain injury (TBI). In addition to characterizing TBI sequelae, evidenced-based neuropsychological assessment can contribute to TBI patient care by aiding with prognostic assessment, measuring interval change/recovery over time (eg, resolution of posttraumatic amnesia), informing and implementing rehabilitation strategies, and evaluating the effectiveness of interventions.
Key points
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Neuropsychology is a subspecialty of professional psychology that involves the scientific study and clinical application of brain-behavior relationships.
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Neuropsychological evaluation integrates objective psychometric tests with other clinical data to comprehensively characterize the cognitive, behavioral, and emotional effects secondary to traumatic brain injury (TBI).
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Neuropsychological evaluation can help delineate normal individual differences from the neurologic effects of injury. Neuropsychological testing is also useful for identifying if psychological conditions (eg, depression) or other non-neurologic factors are affecting symptom presentation.
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Neuropsychological evaluation can further contribute to evidence-based TBI patient care through serial assessment of cognitive and functional status over time, informing TBI rehabilitation, and evaluating the effectiveness of interventions.
An overview of neuropsychology
Neuropsychology involves the scientific study and clinical application of brain-behavior relationships. It is a specialty of professional psychology that “applies principles of assessment and intervention based upon the scientific study of human behavior as it relates to normal and abnormal functioning of the central nervous system.” A clinical neuropsychologist has advanced doctoral education as well as internship and specialty postdoctoral residency/fellowship training in the foundations of brain-behavior relationships (eg, functional neuroanatomy, neurologic disease, and psychopharmacology) in addition to clinical (eg, psychopathology and personality assessment) and general (eg, learning, development, and statistics and psychometrics) psychology. Specialty board certification in clinical neuropsychology is also available.
Professionally, clinical neuropsychologists engage in evaluation/assessment, intervention, consultation, and research related to the cognitive, behavioral, and emotional manifestation(s) of known or suspected brain dysfunction with an extensive array of clinical populations, such as TBI and other acquired brain injury (eg, anoxia and stroke), neurodegenerative/dementing and neurologic conditions (eg, Alzheimer disease, Parkinson disease, multiple sclerosis, and epilepsy), learning disorders, neurodevelopmental conditions, and psychiatric disorders. Among the varied professional activities performed by clinical neuropsychologists, evaluation through the use of objective, psychometric tests is most predominant and serves as the main focus of this review, with emphasis on its relevance to moderate to severe TBI.
An overview of neuropsychology
Neuropsychology involves the scientific study and clinical application of brain-behavior relationships. It is a specialty of professional psychology that “applies principles of assessment and intervention based upon the scientific study of human behavior as it relates to normal and abnormal functioning of the central nervous system.” A clinical neuropsychologist has advanced doctoral education as well as internship and specialty postdoctoral residency/fellowship training in the foundations of brain-behavior relationships (eg, functional neuroanatomy, neurologic disease, and psychopharmacology) in addition to clinical (eg, psychopathology and personality assessment) and general (eg, learning, development, and statistics and psychometrics) psychology. Specialty board certification in clinical neuropsychology is also available.
Professionally, clinical neuropsychologists engage in evaluation/assessment, intervention, consultation, and research related to the cognitive, behavioral, and emotional manifestation(s) of known or suspected brain dysfunction with an extensive array of clinical populations, such as TBI and other acquired brain injury (eg, anoxia and stroke), neurodegenerative/dementing and neurologic conditions (eg, Alzheimer disease, Parkinson disease, multiple sclerosis, and epilepsy), learning disorders, neurodevelopmental conditions, and psychiatric disorders. Among the varied professional activities performed by clinical neuropsychologists, evaluation through the use of objective, psychometric tests is most predominant and serves as the main focus of this review, with emphasis on its relevance to moderate to severe TBI.
Clinical utility of neuropsychological evaluation
Although modern neuroimaging techniques have greatly reduced the historical role of the neuropsychologist in localizing lesions of the central nervous system based on psychometric testing, neuropsychological evaluation continues to meaningfully contribute to patient care by elucidating the functional sequelae secondary to central nervous system pathology/dysfunction. From a clinical and patient care standpoint, this is particularly valuable given that similar structural neuroanatomic lesions can have striking diverse cognitive and behavioral symptom presentations among individual patients. Consequently, there are 6 broad clinical questions that commonly generate a referral for a neuropsychological evaluation :
| Referral Question | Examples |
|---|---|
| 1. Differential diagnosis | Are the patient’s reported cognitive difficulties due to TBI or is some other condition, such as a psychiatric disorder, sleep disturbance, chronic pain, or substance misuse, or are other non-neurologic factors contributing? |
| 2. Characterization of cognitive, behavioral, and emotional abilities/limitations | What cognitive and behavioral deficits does a patient with a moderate TBI have? How may these affect daily functioning? How have a patient’s cognitive deficits resulting from a penetrating TBI and subsequent posttraumatic epilepsy changed over the past year since initial evaluation? Is a treatable psychiatric condition that can have an adverse impact on engagement in TBI rehabilitation (eg, depression) present? |
| 3. Treatment planning | What specific cognitive impairments should be targeted for rehabilitation for a patient with a subarachnoid hemorrhage? What behavioral interventions would be effective for a patient with disinhibited and hypersexual behavior after TBI? What academic accommodations does a patient with a TBI and residual cognitive deficits need if he/she wishes to pursue college coursework? |
| 4. Treatment evaluation | Has there been an improvement in mental status and cognition after surgical evacuation of a subdural hematoma? Has the patient’s attention improved after initiation of medication X? Has a cognitive remediation protocol resulted in an improvement in the patient’s memory? |
| 5. Research | Is a newly developed test able to accurately predict cognitive and functional outcomes after TBI? Has an investigational medication resulted in objective improvements in cognition among patients with TBI? |
| 6. Forensic | Does this person have cognitive deficits from a TBI sustained during a workplace injury that prevents him/her from holding employment? |
Deconstructing the neuropsychological evaluation
The interpretation of neuropsychological test results is central to the role of clinical neuropsychologists and their unique expertise in the neuroanatomic correlates of cognition, neurologic disease processes, statistical analysis, and measurement. A vast majority of non-neuropsychologists, however, understandably view test selection and interpretation as the most enigmatic aspect of the neuropsychological evaluation. The seemingly endless test descriptions, standard scores, and percentiles in reports can seem overwhelming and unintelligible to other health care providers. The forthcoming sections attempt to explain approaches to neuropsychological test interpretation and highlight the importance of evidence-based neuropsychological measurement principles to avoid underpathologizing or overpathologizing patients.
It is also essential for consumers of neuropsychological services to understand that test scores represent only 1 component of an evaluation. Additional data sources might include a patient’s medical record (eg, history and physical, neuroimaging findings, and active medications), behavioral observations both during testing and in the clinical milieu, a neurobehavioral examination, assessment of psychological symptoms, including personality idiosyncrasies and/or personality disorders, and often most importantly, an interview with collateral sources. As such, although other clinical disciplines may have familiarity with individual aspects of functioning (cognition, mental health, and so forth), a unique contribution of neuropsychological evaluation is that it integrates the totality of this information to establish a comprehensive conceptualization of a patient’s cognitive, emotional, and behavioral functioning after TBI.
Test Selection
Counterintuitively, the first step of neuropsychological test interpretation begins before any tests are administered, with the selection of appropriate measures. Proper test selection depends on several variables, including consistency over time (ie, reliability), susceptibility to measurement error, association with theoretically similar/dissimilar tests (ie, validity), and lesion analysis research demonstrating tests’ relationships with neural structures and systems. Several other factors that affect baseline expectations for neuropsychological test performance need to be considered, including age, level and type of education, occupational achievement, primary language, ethnicity, reading level, and physical disability. A patient’s expected level of cognitive impairment also needs to be anticipated to avoid ceiling or floor effects in the selected tests. Failing to consider any of these factors compromises the accuracy of neuropsychological test interpretation before an evaluation begins.
Once psychometrically sound measures are selected, neuropsychologists often take 1 of 2 approaches to neuropsychological evaluation: the fixed battery approach or the flexible battery approach. The fixed battery approach involves administration of the same tests to every patient in a standardized manner. Examples of fixed batteries are the Halstead-Reitan Neuropsychological Battery and the Meyers Neuropsychological Battery. This approach allows for the comprehensive and systematic assessment of multiple cognitive domains, which allows neuropsychologists to make direct comparisons between patients’ performance over time to assess decline or monitor recovery. Disadvantages of the fixed batteries include their length (ie, up to 8 hours of testing) that can lead to higher health care costs and poor patient tolerance for such a long session. Additionally, fixed battery assessments may include the administration of superfluous measures that are not be required to answer the referral question.
In response to the limitations of the fixed-battery approach, most neuropsychologists use a hypothesis-driven or flexible battery approach toward test selection. Flexible batteries are tailored to the needs of individual patients based on the referral question, medical history, and information gathered during the clinical interview. A brief set of probing tests is initially administered, and additional in-depth tests of more specific abilities are completed if a patient exhibits deficits on any initial measures. A popular flexible approach to testing is the Iowa-Benton method, which requires that clinicians administer a core battery that is followed-up with tests that assess suspected impairments in more detail.
Test Validity Versus Assessment Validity
Whether or not a fixed or flexible battery approach is used, neuropsychological evaluations are only useful if a patient’s personal performance and symptom report are an accurate reflection of cognitive abilities. Outright malingering, adoption of the sick role, somatization, chronic pain, and a litany of other secondary influences on cognitive functioning often can lead to artificially low test scores that may result in misdiagnosis and treatments that harm the patient. A complete neuropsychological evaluation includes objective measures of assessment validity, which Larrabee succinctly defines as the ability to determine if an individual patient is producing valid test results during the evaluation. Assessment validity differs from test validity, which is related to the psychometric properties of individual neuropsychological tests (eg, construct and criterion validity) regardless of patient performance.
Assessment validity can refer to either symptom validity or performance validity. Symptom validity refers to patients’ self-reported symptoms and complaints. Symptom validity tests are often found in personality inventories and other questionnaires that require patients to describe their subjective experience of physical, cognitive, and emotional problems. Examinees’ reported symptoms are compared with the reports of various patient groups to determine if their responses are consistent with known conditions. In contrast to symptom validity tests, performance validity tests (PVTs) identify whether or not a patient’s objective cognitive test results are a valid reflection of neuropsychological functioning. Stand-alone tests dedicated to assessing performance validity, measures embedded with genuine tests of ability, and atypical patterns of results are all used to establish performance validity. Multiple PVTs throughout the battery are necessary to minimize false-positive errors and avoid labeling genuine impairment as noncredible. Furthermore, it is recommended that each PVT have a specificity of at least 90%. Sensitivity and specificity are often established through known-groups studies, which compare PVT results of a genuine patient group with that of healthy individuals instructed to feign symptoms of the genuine patient group.
A substantial amount of research on PVTs has been conducted in patients with brain injury, in particular mild TBI (mTBI) (ie, concussions), simulators, and patients with moderate to severe TBI. Using various statistical methodologies, such as chained likelihood ratios, this research has consistently established that if a patient with a history of mTBI in the context of substantial external incentive (eg, military benefits, litigation, and criminal prosecution) fails 2, 3, or more PVTs during an evaluation, then the false-positive rate is practically zero and it can be safely concluded that non-neurologic factors (eg, feigning) are artificially lowering scores. If malingering is suspected, criteria for malingered neurocognitive dysfunction have been established to meaningfully integrate results from validity measures, clinical history and context (benefits, prosecution, and so forth), and testing behavior to provide a rationale for discerning whether a patient is purposefully underperforming. These criteria are particularly helpful in cases of mTBI where persistent cognitive impairments are not expected.
Neuropsychological Domains and Tests
The table below outlines the domains often assessed in an evaluation as well as some common tests that may be encountered in an evaluation report. Before proceeding, however, 3 important caveats are in order. First, this list is by no means inclusive. Readers are referred to other authoritative references for a complete compendium of neuropsychological tests as well as the Center for Outcome Measurement in Brain Injury for additional TBI-specific measures. Second, the specific domains assessed/tests administered in any single evaluation vary based on the referral question and clinical presentation. For example, it is unlikely that full academic achievement testing is indicated in a 75-year-old patient with a subdural hematoma secondary to a fall. Likewise, assessment of a patient with acute posttraumatic amnesia (PTA) and agitation may initially involve bedside serial monitoring with orientation and behavioral measures followed by comprehensive evaluation after resolution of PTA. Third, although each test is listed under the domain it is primarily intended to measure, it is essential to understand that few tests are pure measures of a specific cognitive ability. For instance, a patient with severe visuospatial impairments may perform poorly on a confrontation naming test due to difficulty with accurately perceiving test stimuli rather than a frank language deficit.
| Domain of Functioning | Neuropsychological Tests |
|---|---|
| Serial monitoring after acute TBI | JFK Coma Recovery Scale-Revised Orientation Log Galveston Orientation and Amnesia Test Agitated Behavior Scale |
| General cognitive functioning and full neuropsychological batteries | Wechsler Adult Intelligence Scale–Fourth Edition Halstead-Reitan Neuropsychological Test Battery Repeatable Battery for the Assessment of Neuropsychological Status Neuropsychological Assessment Battery |
| Academic achievement | Woodcock-Johnson Tests of Achievement–Fourth Edition Wide-Range Achievement Test 4 |
| Sensory-motor functions | Grooved Pegboard Test Finger Tapping Test |
| Language | Multilingual Aphasia Examination Boston Diagnostic Aphasia Examination Boston Naming Test Verbal Fluency Tests |
| Visuospatial/constructional | Judgment of Line Orientation Hooper Visual Organization Test Clock Drawing Test |
| Learning and memory | Rey Auditory Verbal Learning Test Rey Complex Figure Test California Verbal Learning Test–Second Edition Wechsler Memory Scale–Fourth Edition |
| Attention | Ruff 2 and 7 Selective Attention Test Trail Making Test Paced Serial Addition Test Continuous performance tests Symbol Digit Modalities Test |
| Executive functions | Wisconsin Card Sorting Test Delis-Kaplan Executive Function System Booklet Category Test Stroop Test |
| Functional abilities | Independent Living Scales Texas Functional Living Scale |
| Emotional functioning/personality | Minnesota Multiphasic Personality Inventory-2 Personality Assessment Inventory Beck Depression Inventory–Second Edition |
Related posts:
Management of Medical Complications During the Rehabilitation of Moderate-Severe Traumatic Brain Injury
Diagnosis and Management of Acute Concussion
Rehabilitation of Persistent Symptoms After Concussion
Educational and Vocational Issues in Traumatic Brain Injury
Research Frontiers in Traumatic Brain Injury
Toward a Postmodern Pragmatic Discourse Semioethics for Brain Injury Care
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