Current Test Batteries and Need for Development

Helena Hanninen

Behavioral toxicology is an applied branch of psychology with a very practical aim: to detect neurotoxic effects for the planning of prevention among exposed populations.

The earliest research in clinical and epidemiological behavioral toxicology was done within occupational medicine by psychologists working close to it or by medical doctors with some familiarity with psychological methods. Most of the research in the area is still done in this context. It provides the best possibilities for collaboration with the other disciplines working toward the same goal. In this context, however, the connections of behavioral toxicology with other branches of psychology—applied, as well as theoretical—have been loose. Reports are seldom published in psychological journals but rather in those of occupational medicine or neurotoxicology because of the practical relevance of study results within these disciplines. As a consequence, research on behavioral toxicology has been little known to those working in other fields of psychology. Another consequence is a limitation of scientific feedback from colleagues in other branches of psychology.

However, psychologists doing research on behavioral toxicology do use the knowledge and methods developed in other fields of psychology. Methods of behavioral toxicology originate from different branches of applied and academic psychology: clinical psychology, neuropsychology, aptitude testing, psychophysiological psychology, and in recent years, cognitive psychology.

Tests were borrowed from

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

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these fields, mostly without trying to incorporate the corresponding theoretical framework into behavioral toxicology. The theoretical framework has been regarded as less important than the efficiency of the tests in detecting neurotoxic effects and their applicability in epidemiological research.

TEST BATTERIES NOW IN USE

Epidemiological and Field Studies

The methods now in use in epidemiologically oriented behavioral toxicology compose an interesting variety of psychological tests. Eight studies published in 1985–1987 serve as examples (Table 1). The variety of tests used reflects the history of behavioral toxicology and, to a certain extent, the advances of psychological testing during that period.

One of the first comprehensive test batteries for the detection of neurotoxic effects was designed at the Institute of Occupational Health in Finland, in connection with a study on carbon disulfide (Hanninen, 1971). It was composed of the best tests on hand at that time. First a very large selection of tests was used; there were tests of clinical psychology and neuropsychology, as well as aptitude tests standardized at the institute. Then, after preliminary data analyses, those tests of different areas of functioning were selected which seemed to be sensitive and suitable for use in clinical practice as well as in epidemiological research. Over the years the battery has been modified, and in each of the Finnish studies a somewhat different selection of tests has been used, depending on the exposure agent in question and the overall study design. Study 1 (Mantere et al., 1984) in Table 1 is one example. Descriptions of the tests were published in a separate booklet (Hanninen and Lindstrom, 1979), and several of them have spread to wider use in behavioral toxicology: the Santa Ana dexterity test, the Bourdon-Wiersma Vigilance test, the Benton test for visual memory, and selected subtasks of the Wechsler Adult Intelligence Scales (WAIS). Tests of WAIS and WMS (Wechsler Memory Scale) as well as the Benton Visual Retention test have been much used also because they are well documented and have been standardized in several countries. Other neuropsychological tests have been adapted to behavioral toxicology, too.

Studies 2 and 3 are other examples of test batteries composed mainly of much-used neuropsychological tests. The tests are not the same, however. The battery used in study 2 (Baker et al., 1984) was composed of subtasks of the Wechsler Scales; verbal memory was empha

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sized. Santa Ana was used for psychomotor ability. The British battery (Cherry et al., 1984) used in study 3 (Cherry et al., 1985) has three psychomotor tests and three for visual-motor performance. Of the latter, the Visual Searching task was devised by Goldstein as an indicator of brain damage, and Trail Making is from the Halstead Reitan Battery. The two most applied tests of the WAIS, Digit Symbol and Block Design, are also included in this battery. Memory is assessed by one test only. The British National Adult Reading Test (NART) is included as a measure of premorbid ability.

The battery used in study 4 (Jeyaratnam et al., 1986) concentrated even more on visual, motor, and visual-motor functions; each was measured with several tests. Additionally there was Digit Span for memory performance.

Study 5 (Maizlish et al., 1985) is an example of studies that apply methods developed within experimental psychology. There were no common elements with the five previous test batteries, but the battery covers principally the same broad functional domains as these do. Each of the tests contains a long series of measurements (about 15 minutes each), and gives detailed information about the function in question.

Many of the recent test batteries in behavioral toxicology include single computer-assisted tests adapted from other branches of psychology. The Neurobehavioral Evaluating system (NES) developed by Baker and Letz (Baker and Letz, 1986) and used in studies 6 (Maizlish et al., 1987) and 7 (Fidler et al., 1987) is totally computerized. Some of its tests can be described as computerized versions of certain conventional tests that have shown sensibility in toxicity testing; some were chosen or designed as promising new tests for that purpose. Being an extensive battery, the NES provides an opportunity to choose relevant methods for different kinds of studies. In addition to the tests used in studies 6 and 7, the regular sequence of NES tests also includes a verbal Associate Learning task and a vocabulary test for obtaining a measure of initial intelligence level.

The last study in Table 1 (Williamson and Teo, 1986) is another example of new methodological approaches in behavioral toxicology. Its tests were selected on the basis of information-processing theory, which also provides the framework for interpreting the results.

BEHAVIORAL TOXICOLOGY IN CLINICAL PRACTICE Behavioral toxicology aims at examining and identifying toxic effects on the functional capacity of the central nervous system (CNS).

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

Behavioral Measures of Neurotoxicity http://www.nap.edu/catalog/1352.html

TABLE 1 Eight Batteries for Behavioral Toxicity Testing Study 1

Mantere et al.

(1984)

Study 2

Baker et al. (1984) Study 3 Cherry et al.

(1985)

Study 4 Jeyaratnam et al.

(1986)

1. Flicker Fusion

2. Santa Ana

Dexterity Santa Ana Dotting

Grooved Pegboard Simple Reaction Time

Santa Ana Simple Reaction Time

3. Bourdon-Wiersma Vigilance

Digit Symbol (WAIS)

Digit Symbol (WAIS) Visual Search Trail Making

Bourdon- Wiersma Digit-Symbol (WAIS) Visual Search Trail Making 4. Block Design

(WAIS)

Picture Cimpletion (WAIS)

Block Design

(WAIS) Block Design

(WAIS)

5. Visual Reproduction (WMS)

Visual Reproduction (WMS) Digit Symbol Recall 6. Digit Span (WAIS,

WMS)

Logical Memory (WMS)

Digit Span (WAIS, WMS)

Associate Learning (WMS) Mental Control (WMS)

Animal Names

(Bushke) Digit Span (WAIS)

7. Similarities (WAIS) Similarities (WAIS) Vocabulary (WAIS)

Reading Test (NART)

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

Behavioral Measures of Neurotoxicity http://www.nap.edu/catalog/1352.html

Study 5 Maizlish et al.

(1985)

Study 6 Maizlish et al.

(1987)

Study 7

Fidler et al. (1987)

Study 8 Williamson and Teo (1986)

1. Flicker Fusion

2. Tapping: Fitts

Law Task NES Finger

Tapping NES Hand-Eye

NES Hand-Eye Hand Steadiness Simple Reaction Time Visual Pursuit 3. Stroop Test NES Continuous

Performance NES Symbol Digit

NES Continuous Performance NES Symbol Digit

Sustained Attention 4. Mental Rotation NES Pattern

Comparison 5. Memory

Scanning Memory Span Continuous Recognition Memory

NES Pattern

Memory NES Pattern

Memory Sensory Store

Memory Paired Associates

6. Memory Scanning Memory Span Continuous Recognition Memory

NES Digit Span NES Memory Scanning

Sensory Store Memory Paired Associates

8. NES Mood Scale NES Mood Scale

NOTE: Areas tested: 1 = sensory function; 2 = motor ability; 3 = attention and sensory-motor speed; 4 = visual intelligence/ spatial reasoning; 5 = visual memory; 6 = verbal memory; 7 = verbal intelligence/vocabulary; 8 = mood.

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

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The subject matter links it with neuropsychology. The methodological choices described above reflect this link, but not consistently. The neuropsychological orientation is particularly relevant when neurobehavioral methods are used for clinical assessment of individuals afflicted by neurotoxic exposures.

In Scandinavia and in some other European countries, psychological assessment is a rather regular part of diagnostic procedure when a neurotoxic occupational disease is suspected. Moreover, at least in Finland, it is rare for referral of such a patient to be based on psychological examination done in a neurological clinic or a public health center. Neuropsychologists in other countries have been less aware of the neurotoxic syndrome, but the situation seems to be changing rapidly.

Neurobehavioral dysfunctions seen in intoxication patients provide useful information that directs the choice of methods when the early effects are studied, and vice versa: results of the epidemiological studies have guided the selection of tests in clinical test batteries. Table 2 lists the tests included in three diagnostic test batteries: the one used by Bolla-Wilson and Bleecker in the Johns Hopkins School of Medicine (Bolla-Wilson and Bleeker, 1987); the Pittsburgh Occupational Exposures Test Battery, or POET (Ryan et al., 1987), which is meant for use at clinics as well as in research; and the battery now in use at the Finnish Institute of Occupational Health (IOH).

The first battery represents traditional neuropsychological methodology;

the two others were designed especially for neurotoxic effects. Differences among the three batteries are not striking. All of them sample roughly the same broad functional domains, with one or more tests. The tests selected are not the same, however. Only four WAIS tests appear in all three batteries. Seven tests are included in two of them. Additionally, each battery contains tests not present in the two others. There are also differences in emphasis. The Finnish battery attempts a detailed description of the motor performance and its disturbances, whereas there is only one ordinary psychomotor test in the two other batteries. On the other hand, the set of memory tests included in POET allows a much more elaborate description of the memory function than the Finnish battery does, and the battery used by Bolla-Willson and Bleecker is the only one that assesses verbal functions that may be affected by toxic exposure.

BASES OF TEST SELECTION

Published studies in behavioral toxicology seldom give reasons for selection of test methods: reports emphasize results, not methodol

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

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TABLE 2 Three Clinical Test Batteries for Neurotoxic Syndromes Bolla-Wilson and

Bleecker^a Ryan (POET) IOH, Helsinki

2. Simple Reaction Time Grooved Pegboard Finger Tapping Santa Ana Mira Staircases 3. Digit Symbol (WAIS-R) Digit Symbol (WAIS-R) Digit Symbol (WAIS)

Stroop Test Bourdon- Wiersma^b

4. Block Design (WAIS-R) Block Design (WAIS-R) Picture Completion (WAIS-R) Boston Embedded Figures

Block Design (WAIS) Picture Completion (WAIS-R) Symmetry Drawing^b

5. Visual Reproduction (WMS) Symbol-Digit Learning

Visual Reproduction (WMS) —immediate and delayed Symbol- Digit Learning — immediate and delayed Digit Symbol Retention

Benton Test Digit Symbol Retention Visual Reproduction (WMS)^b

6. Serial Digit Learning Verbal-Verbal

Associates Rey Auditory Verbal Learning Logical Memory (WMS)

Digit Span (WAIS-R) Verbal Paired Associates Recurring Words

Digit Span (WAIS-R) Associative Learning (WMS) Logical Memory (WMS)^b 7. Similarities (WAIS-R)

Vocabulary (WAIS-R) Verbal Fluency (FAS)

Similarities (WAIS-R)

Information Similarities (WAIS-R) Synonyms

8. POMS

Rorschach^b

NOTE: Areas tested: 1 = sensory function; 2 = motor ability; 3 = attention and sensory-motor speed; 4 = visual intelligence/spatial reasoning; 5 = visual memory; 6 = verbal memory; 7 = verbal intelligence/vocabulary; 8 = mood.

a Only tests used in follow-up are listed.

b Optional tests.

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

Behavioral Measures of Neurotoxicity http://www.nap.edu/catalog/1352.html

ogy. This does not mean that there was no rationale for choosing the particular tests used. Very often, however, the rationale can only be guessed.

In the choice of tests, the first questions considered are the following:

What behavioral/neuropsychological functions are likely to be affected? Which tests are available for examining those functions? The answer to the second question yields, in principle, a wide selection of relevant tests. To choose among them, further questions must be considered. Important criteria are (1) previous empirical evidence of the sensitivity of the tests with regard to the effect looked for; (2) other previous documentation of the test: its psychometric properties, general population norms, documentation of its construct validity, etc.; (3) suitability and acceptability of the tests for the subjects to be tested; and (4) costs and benefits of the tests: costs in terms of time, expertise, and equipment needed; benefits in terms of information provided by the method.

The existing differences in test selection (Tables 1 and 2) reflect different answers to these questions or a different importance given to them.

Most test series include measures of a wide area of behavioral functions.

This indicates that the authors either expected the effects to be widespread and diffuse, or did not have specific expectations concerning the functions to be affected. It is also possible that they had such expectations, but wanted to sample a broader area of function to be better able to circumscribe the effect.

Some differences in the emphasis given to different functional areas were also found: some batteries emphasized psychomotor tasks; others, cognitive tests, or memory tests in particular. These differences seemed not to be related to the exposure agent under study, but rather to reflect different concepts of the nature of the neurotoxic syndromes in general.

The tests chosen to measure different behavioral areas varied more than the general structure of the batteries. Some classic neuropsychological tests seem to be rather well-established general tools in behavioral toxicology, but there were also batteries that had very few common elements with the others, or none at all. One explanation is that the authors represented different branches of psychological research and preferred tests that best corresponded to their education and experience. Moreover, the studies were conducted in different countries where different tests may have been available and well documented with general population norms, etc.

It seems also that the previously established sensitivity of the test in regard to toxic effects was not considered equally important by all of researchers.

Rather, the authors can be classified as conservative

METHODS IN BEHAVIORAL TOXICOLOGY: CURRENT TEST BATTERIES AND NEED FOR DEVELOPMENT

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or progressive. The former prefer the ''old'' tests because there is previous documentation about their sensitivity and the possibility of comparing their results with earlier ones. At the same time, the users of these tests may be troubled by their weaknesses: questionable reliability, low acceptability by the subjects, laborious scoring, etc. The "progressive" authors, on the other hand, strive to introduce recent theoretical or methodological progress in different branches of psychology into the field of behavioral toxicology. Their problem is that in using new promising and potentially sensitive methods, they lose the possibility of comparing their results with early research. Also, in case of negative results, they have difficulty in deciding whether the exposure in question actually had no behavioral effect or whether the promising methods indeed were not sensitive enough to display them.

Consideration of the population to be investigated is also necessary when selecting a test. The suitability of a test depends partly on the general educational level and culture of the subjects, and on the cultural and educational homogeneity of the subject group. In culturally and linguistically very heterogeneous populations the methodological choices are limited mainly to sensory and motor tests. Moreover, the practical circumstances of the study outlined by the study design, the testing facilities (particularly in field studies), and economic matters may strongly restrict methodological choices, making a wise test selection a real challenge.

THE NEUROBEHAVIORAL CORE TEST BATTERY

The Neurobehavioral Core Test Battery (NCTB) was designed by an expert group of the World Health Organization (WHO). It is intended for use in health hazard evaluations and field studies when the testing time is limited and the use of sophisticated equipment is not possible (Johnson, 1987). The seven tests included in the NCTB can also be recommended as common tests in more comprehensive test batteries, to allow comparison of results obtained by different research groups.

The NCTB includes Pursuit Aiming for motor steadiness, Simple Reaction time for attention and response speed, Digit Symbol for perceptual motor speed, Santa Ana for manual dexterity, the Benton Visual Retention test for visual perception and memory, and the Digit Span test for auditory memory. The Profile of Mood States (McNair et al., 1981) is included as a measure of affect.

When tests were chosen for the NCTB, special consideration was given to their applicability for examining working populations all over the world where

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