In recent years, there has been increasing use of neuropsychological testimony in cases of head trauma and other situations which can lead to impairment of brain function. The rapid growth in this area has left some confusion as to the potential role of the psychologist and the role of neuropsychological testing in such cases. This article will address these issues, highlighting the major uses and issues in the area. For our purposes here, we will concentrate on the use of the Luria-Nebraska Neuropsychological Battery (LNNB). However, many of the comments can be applied to the more general area of the role of neuropsychological testing.
BASIC USES OF NEUROPSYCHOLOGICAL TESTING
Traditionally, neuropsychological testing has been used to identify whether the deficits shown by a patient are "organic" (related to injury to the brain) or "functional" (related to psychiatric disability). However, the recent growth of neuropsychology was not predicated on this traditional role, but rather has arisen with the recognition that a diagnosis of "organic" is at best only a first step in a more comprehensive analysis. One can have organic deficits which result in no real behavioral problems. Psychiatric disability can easily co-exist with brain injury, and indeed can be caused or complicated by brain injury.
As a result, neuropsychology has turned away from emphasizing such simple discriminations as an ultimate goal (although such a determination can represent a valid, initial step in a forensic case so as to determine whether further work is warranted). In modern neuropsychological examinations, the final goal of testing includes several interrelated steps: 1) determination of the presence of a brain dysfunction; 2) determining the extent and nature of the deficits caused by an injury; 3) determining the role of such deficits in an individual's ability to work, handle family responsibilities, take care of themselves, handle stress, and function inter-actively with other people; 4) determine the probable relationship of the deficits to the head injury or other hypothesized causes; and 5) to design rehabilitation or other treatment programs which will allow the individual to take maximum advantage of his or her remaining capacity.
Of crucial importance in achieving these goals is the acquisition of adequate and reliable data on which to base such opinion. In making decisions on how to do this, two major approaches have gained popularity. First, the clinical approach, in which reliance is placed on unstandardized assessment instruments and which relies almost completely on the clinical skills of the investigator. This approach is best exemplified by the work of Luria and others who identify with behavioral neurology.1 The second approach takes the stand that the contribution of neuropsychology lies in the use of standardized tests whose interpretation is determined by empirically-derived rules and relationships. At its extreme, this approach re-emphasizes the need to interact with the patient, and de-emphasizes the role of the individual clinician. Indeed, the ultimate goal of such an approach would be a computer program which could determine the diagnosis (and perhaps treatment) without the need for clinical intervention. This has been exemplified by some of the uses of Halstead and Reitan's work2 and by the quickly growing area of computer programs designed to interpret such tests as the WAIS. (In some cases, the computer not only interprets the test, but gives it as well.)
Arguments can be made for both approaches. The clinical approach emphasizes the training and skills of the clinician. However, it suffers from the problem that two clinicians seeing the same case may disagree. In a court setting, this has the drawback of depending primarily on opinions rather than objective evidence which can allow the judge and jury to make a decision between conflicting testimony. It also has the drawback of essentially replicating the work of the behavioral neurologist: it does not take advantage of any of the unique skills which the psychologist can bring to a case.
The quantitative approach has the advantage of theoretically relying on objective evidence and rules derived from research and replicated in a variety of different settings. Thus, the court can be given objective, replicable evidence on which to make a decision, a situation which makes such a technique extremely powerful. In addition, by deemphasizing the role of the clinician and the "expert" the data can be checked by other nonexperts and the court can more easily make decisions between competing experts.
However, there are drawbacks to this. A primary problem is the fact that none of the empirical rules predict with absolute accuracy; indeed, for the majority of empirical rules available, the accuracy rate can vary as low as 65% or less depending on how precise an answer is required. Hit rates are higher for simple questions (Is there brain damage?) but much lower for complex questions (Can this person do a specific job?). In addition, demographic or other factors such as sex, education, socioeconomic status, peripheral disorders, psychopathology, are not well-quantified and so lead to increased error rates. This is exacerbated when these tests are used by many who are not experts and do not understand the test limitations.
This state of affairs has led many to suggest that the field needs to see an integration of these techniques: the use of empirically verified batteries of tests, supplemented by non-standardized or other procedures when necessary, and interpreted not only by empirical rules but also by a clinician who has expertise in the area of brain-behavior relationships. In doing this, the expectation is that the strengths of both approaches could enhance one another, leading to a higher rate of accuracy than either method alone. Ideally, tests chosen for such a battery would be those which could readily be used as sources of information for both approaches.
The LNNB was designed with the purpose of being useful both for the empirical analysis of brain damage and for presenting the data and testing in such a way as to make it useful for clinical/ qualitative evaluations. As such the battery is not a pure but rather a hybrid approach. Like other empirical tests, it yields a range of scores whose pattern can be interpreted for the presence and nature of damage in an individual.
The LNNB differs from other tests, however, in the way items on the scale are chosen. A "Motor" scale on a traditional test might consist of 15 attempts to do the same motor movement or some similar activity. On the LNNB, each item on the motor scale involves motor movement, but each item is essentially different from its neighbor, examining a different aspect of the overall domain of motor skills. From a purely psychometric point of view, this would tend to reduce thé "content validity" of the scale since all items are not measuring the same thing. The scales could be described as more heterogeneous than homogeneous since one might see a test like Vocabulary on the WAIS. On the other hand, by enhancing the range of items, the clinician can make a much larger range of observations on the patient, observing performance under a wide variety of conditions. This in turn allows one to more precisely describe and observe the exact nature and limitations of the patient's deficit. By doing so, one can make much better predictions to such areas as work adjustment and rehabilitation. By examining a larger range, the test approaches (but does not necessarily duplicate) the kind of examination done by Luria.3
In order to increase both the empirical and the clinical utility of the battery, the test alone has qualitative scoring scales in which such disorders as perseveration are measured across scales to provide empirical evidence for the "whys" of specific behaviors, an important question in the clinical analysis of the test.
Interpretation of the test is done through empirical analysis of the scale score patterns, through empirical analysis of the patterns of each individual item within and across the scale, through analysis of the qualitative scores, and clinical analysis of the "why" behind each error and integration of relevant historical, medical, psychosocial, psychiatric, and environmental data. Conclusions are reached only after thorough integration of the clinical and empirical analyses. Thus, one has the advantage in court of offering expert clinical opinion backed by objective evidence, and of backing empirical conclusions by an expert qualitative analysis. Such a combination - built into a single test battery - offers an extremely influential combination. More precise data on interpretation may be found elsewhere.4,5
With the introduction of this two-tiered system also comes needs for evaluating user qualifications ; proper use of the LNNB at its full potential requires an individual to understand both the psychometric and clinical aspects of the test. The individual who uses only empirical findings is not using the advantages offered by the structure of the LNNB. However, full use of the system requires training of the individuai in neuropsychology at a level significantly beyond that given to most clinical psychologists. The additional training falls into the areas of complete familiarity with neuropsychological theories of brain behavior relationships, an understanding of the basic mechanisms involved in head trauma and other neurological disorders, experience in testing and assessing brain-injured individuals, and experience in interpreting neuropsychological test results within a large and varied population of patients with neurological deficits.
While programs for training neuropsychologists have received extensive attention in the past few years,6 there are actually few formal programs providing such training at levels adequate for practice in the field. More importantly for the present, individuals currently active in the field have with rare exceptions been trained in informal circumstances, achieving recognition in the field through research and teaching and the recognition of peers rather than through participation in formal training programs.
The lack of clear-cut credentials makes it difficult to identify who is qualified to be an expert witness. In the past 12 months, there has been the introduction of two boards which are seeking to certify neuropsychological practitioners who are recognized as having at least the basic credentials for diplomate status. Certainly, the attainment of such a status can be one sign of qualification in the area. Additional qualifications can include recognition by peers within neuropsychology, publication in referenced journals, completion of available training programs, completion of workshops in specific areas, experience with appropriate populations under supervision by qualified neuropsychologists or other professionals with equivalent training, training in assessing psychiatric disorders in cases where such disorders can be involved, and specific experience and training with the test instruments which are employed (on both sides).
Several cautions are in order when evaluating credentials using these criteria. Workshop training cannot give experience or truly supervised case training and is limited generally to the facts in the area and the empirical rules. They rarely are able to give the clinical skills also necessary to properly use tests; as a consequence, when training is limited to Workshops alone, caution must be taken in analyzing a potential expert's abilities. This does not mean that such training is useless, only that it must not be regarded as final training in creating a skilled clinician.
In regard to experience, unsupervised experience in settings where there is little contact with more experienced clinicians in the area can be worse in some cases than no experience at all. In the absence of formal training, claims of experiential training must be regarded carefully. There has been an unfortunate tendency in many settings to create neuropsychologists because of the lack of trained individuals in the field. In these cases, individuals have become neuropsychologists not because of skills but rather because a job was available or as a result of an interest in the area. Some of these individuals have gone on to ensure that they have received adequate training; others have not. The introduction of essentially unqualified people into forensic settings can result in misuse of the tests as well as confound the legal process.
TESTIMONY FROM NEUROPSYCHOLOGICAL TESTING
As noted above, neuropsychological testing can be useful in four major areas. First, it can either confirm or prove the presence of brain dysfunction. In cases where the brain damage has been clearly established by CT scan, EEG, or history (such as a period of significant unconsciousness) the LNNB or other tests should be used to demonstrate the degree to which the brain damage has resulted in cognitive dysfunction. This can be especially important in many cases of head trauma where the fact of the injury will be accepted, but not the presence of residual damage. In such cases the test may be used to contradict or support such assumption, depending of course on the results. In cases where there is a question of whether any injury has occurred, a "clean" test protocol can be used to bolster defense statements while evidence pointing to brain damage consistent with the plaintiffs case can be used to support such a contention.
Tests like the LNNB can be useful to both sides of a case, despite what is generally a higher use of such testing by the plaintiff rather than the defense. For the plaintiff, the test is useful to demonstrate the dysfunction; for the defense, the test can in some cases show that the symptoms demonstrated by the patient may be due to other causes (such as a psychiatric disability). In the latter case, the test is effectively employed in concert with an objective personality assessment. In the author's experience, the LNNB can be powerful in bolstering either side of the case depending on the exact facts.
Once brain damage is established, a detailed description of the exact effects of the brain dysfunction is required. This allows the court to better recognize the nature of the disability. Illustrations of the patient's problems taken from the LNNB are especially useful because the items are easy to explain to judges and juries which gives them a more personal sense of seeing how the diagnosis was arrived at more so than the use of complex tests which are difficult for the layman to understand. The test may also be used to identify areas of good functioning as well as injury, further yielding a more complete picture of the dysfunction. Such a balanced presentation is generally welcomed by the court as opposed to simply emphasizing only strengths or only weaknesses. In cases where there is significant dispute over the nature of the patient's deficits, LNNB testing should be followed up with tests chosen to illustrate the exact nature of the deficits. By backing up the LNNB with further evidence, the overall results become difficult to contest.
Once the patient's deficits have been identified, it is necessary to relate the symptoms to the specific areas in the patient's life which have been disrupted. One of the advantages of the LNNB is the ability to define the specific deficits (as opposed to more general descriptions) and relate these to an analysis of the skills needed in the patient's work and personal life, while at the same time outlining those areas in which the patient is able to perform. This can of course be useful to both sides in a lawsuit in allowing a more precise understanding of the patient's difficulties.
The final use of the test is to describe rehabilitation programs which may be necessary to improve the patient's functioning, as well as to evaluate the potential success of such programs based on the patient's overall strengths and the type of program which is proposed. This is the most difficult area to comment on because of the lack of clear data, although it generally appears that the presence of intact higher level skills is a good predictor of success, while the absence of such skills generally predicts more life-long disability.7
In using the LNNB in court, several limitations must be considered. First, no neuropsychological test can "prove" that a deficit came from a given injury, only that the deficit is consistent with such an injury. This must be substantiated by an appropriate history which identifies the event as the most likely cause. In cases of subtle head injuries, this means establishing that the deficits were not likely to have existed before the injury.
A second limitation is that deficits which are due to personality changes alone may not show up clearly because of the absence of cognitive dysfunction. Such deficits can be seen in the qualitative scores in such areas as impulsivity, impersistence, emotional behavior, and other similar Categories. These deficits should also be demonstrated with the use of personality tests where such an injury is suspected. (Our own procedure is to make personality tests a routine part of every forensic evaluation.)
Finally, no test battery can cover every possible symptom a patient may show even if we restrict ourselves to cognitive deficits alone. As a consequence, if the patient's behavior or complaints suggest deficits in areas not covered by the LNNB, the LNNB must be supplemented by tests which aim specifically at those areas.
As can be seen from this short introduction, the LNNB and neuropsychological testing can be useful in a number of areas in forensic cases, far beyond those traditional roles assigned to such testing in the past. Combined with a good psychiatric and medical analysis, this combination of techniques can serve to effectively present a case outlining the effects of head injury in a given patient.
1. Luria AR: Higher Cortical Functions in Man. New York. Basic Books, 1980.
2. Russell E, Neuringer C, Goldstein G: Assessment of Brain Damage - A Neuropsychological Key Approach. New York, John Wiley & Sons, 1970.
3. Akhutina TV, Tsvetkova LS: Comments on a standardized version of Luria's tests. Brain and Cognition 1983; 2:129-134.
4. Moses JA, Golden Cl, Ariel R, et a): Interpretation of the Luria-Nebraska Neuropsychological Battery. New York, Crune and Srratton. 1983, vol J.
5. Golden CJ, Purisch A, Hammekke T: Manual for the LuriaNebraska Neuropsychological Battery. Los Angeles, Western Psychological Services, 1984.
6. Meier M: Credenttaling in neuropsychology, in Golden CJ, Vicente P: Foundations of Clinical Neuropsychology. New York, Plenum, 1983.
7. Golden CJ: Diagnosis and Rehabilitation in Clinical Neuropsychology. Springfield, Charles C Thomas, 1981.