The Neuropsychology of Degenerative Brain Diseases

Robert G. Knight

• Publisher: Psychology Press
• Year: 2013
• ISBN:
  9781134993444
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

This volume utilizes various neurological diseases as its organizing principle, focusing specifically on their personal, social, and cognitive consequences. In so doing, it provides neuropsychologists, clinical psychologists, and those in related disciplines with an accessible survey of the available research on the psychological functioning of patients with the various disorders. Each chapter consists of a background review of the major features of one of the diseases, including symptom pattern, neuroanatomical bases, neuropathology, genetic factors, and epidemiology. Finally, the psychological and cognitive deficits established by research are reviewed, and their practical implications are discussed.

PART 1

ASSESSMENT

Chapter 1

ASSESSING THE DEMENTING PATIENT

In the process which we call dementia, the clinical picture is usually dominated by intellectual disintegration, but feeling and striving are always affected. The general features of the syndrome show a fairly consistent pattern which is varied in the individual case according to the premorbid personality, the age of onset, the nature of the cause, and any local preponderance in the early lesions. The impairment of memory for recent events, which is the earliest change, may be effectively compensated for a considerable time by a surprising ingenuity in concealment, adherence to a rigid daily routine and the use of a notebook. This adjustment breaks down as intellectual grasp weakens and thinking becomes slow, labored and ill defined. Attention is now aroused and sustained with difficulty, the patient tires easily, particularly with any unaccustomed task, and he is prone to become lost in the middle of an argument or sentence. Poverty of thought supervenes in a once richly stored, flexible mind: it shrinks to a small core of ever-recurring, rigidly held ideas and re-evoked memories of the remote past, which may long remain vivid and clear. (Mayer-Gross, Slater, & Roth, 1969, p. 491)

Introduction

Nearly every professional contact with a client who has a degenerative brain disease, whether for clinical or research purposes, incorporates some level of formal or informal evaluation of the client's current functioning. Accordingly, it is helpful to begin with a brief review of some of the procedures used in constructing an understanding of the neuropsychological consequences of degenerative brain diseases for individual patients.

Some degree of cognitive failure or functional decline is associated with almost all the degenerative diseases reviewed in this book; these changes are given the generic label of dementia. The Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., rev. (DSM-III-R; American Psychiatric Association 1987) describes dementia as resulting in a deterioration in memory functioning, abstract thinking, judgment, personality, and other higher-order cortical functions, such as language, perception, constructional skills, and conceptual learning. Dementia is invariably present in some disorders, such as Alzheimer's disease (AD), but is less common in others, for example, Parkinson's disease (PD). Studies comparing groups of patients with dementia associated with different degenerative diseases, suggest that there may be variations in the pattern of cognitive disturbance as a consequence of differing distributions of neurological damage. Whether dissimilar profiles of cognitive performance can or cannot be distinguished in patients with diseases of different pathology, in practice the assessment of dementing patients proceeds in much the same way. Selection of appropriate assessment procedures depends more on the severity of the dementia than on the nature of the diagnosis.

The appropriate selection of measures for use with dementing patients depends to a large extent on the purpose of the particular assessment being undertaken. This might be screening for the presence of dementia or documenting consequent changes in performance, both important objectives in the evaluation of clients with degenerative neurological conditions. The valid measurement of the presence or degree of dementia is also important in the process of describing samples of patients used in research. Specific tests will be useful in some circumstances and entirely inappropriate in others. When planning to use standardized measures in research with neurologically impaired clients or for the assessment of individual patients in a clinical setting, it is vital to have the assessment goals clearly defined. Some of the specific objectives of testing are listed here:

Diagnosis. This includes the detection of the onset of a dementing process and, under some circumstances, contributing a more precise diagnosis, such as Alzheimer's disease or multi-infarct dementia. Although physical techniques such as computed tomography (CT) scans have an increasingly important part to play in diagnosis, no amount of scanning can specify exactly what a patient is capable of achieving as far as social or cognitive performance is concerned. Formal psychometric testing may also contribute to differential diagnosis by eliminating alternative explanations for poor cognitive performance, such as depression or concurrent psychiatric disturbance.

Documenting the extent, severity, or stage of the dementing disorder. Frequently a diagnosis has already been established, and the aim of testing is to determine a patient's current level of functioning. In clinical practice, testing is important in planning case management. Knowledge of the severity of the disorder is a prelude to planning rehabilitation, a long-term care strategy, and the mobilization of appropriate support. Necessarily, case management requires the comprehensive assessment not only of cognitive functioning, but also of personality, behavior, social support, and adaptive skills.

Monitoring the effects of treatment or disease progression. Assessing changes in personal functioning or cognition as a consequence of intervention, particularly pharmacological treatment, but also psychosocial remediation, is another objective of testing. Evaluating the rate of deterioration (or in disorders like multiple sclerosis, the degree of remission) is another important clinical task. In this situation, the measures used need to be sensitive to change and relevant to the aims of the treatment or care strategy.

Experimental research. A major use of standardized measures of impairment is the accurate description of groups of patients for research purposes. This includes demonstrating that diagnostic statements are well-founded and establishing the severity of the impairments of the patient tested. This serves to facilitate comparison between the results of different research groups.

Epidemiological research. Planning health services and testing etiological theories that involve environmental risk factors necessitate appropriate community screening and follow-up diagnostic testing to determine the prevalence and incidence of the diseases under consideration.

Numerous published rating scales, objective performance tests, and interview schedules are available to perform the functions just outlined. A selection of these are reviewed in this chapter. There are some advantages to using published scales that have been standardized on relevant samples of patients. One benefit is the enhanced opportunity for integrating research from different laboratories using common procedures. In addition, the process of test construction is laborious; thus, using measures with known psychometric credentials can save time and unnecessary duplication of effort. On the other hand, measures developed by other researchers may not be sufficiently precise or accurate for use in some circumstances. Although the development of a better or more specific test may be time-consuming, the dividends from doing so can be considerable. For example, many clinicians devote considerable time to planning and executing an innovative treatment program, but pay little attention to monitoring the outcome. Use of inappropriate or imprecise outcome measures may preclude the demonstration of a strong treatment effect; in this case failure to spend time constructing powerful measures of treatment efficacy may render the effort expended in treatment worthless.

The choice of particular measures of dementia to meet specific clinical or research goals is obviously dependent on the relevance and scope of the content of scale items. However, there are also other important factors. For example, the usefulness of a test for detecting dementia depends on its discriminatory power. In psychometric terms, discriminatory power depends on test reliability and the difficulty of the items. Increases in reliability can be achieved by making the items more homogeneous or by lengthening the test. The difficulty level of items is something that needs to be considered carefully when selecting or developing a measure for demented patients. Tests with too many easy items may be of little use for discriminating normal from mildly impaired patients, but an excellent way of documenting severity in the moderate range of disability. A more difficult test may be useful for describing deficits in mildly impaired patients, but may be totally beyond the capacity of more demented patients. The discriminatory power or sensitivity of a particular test needs to be carefully considered in relation to the level of deficit a client or group of research subjects may display.

In the remainder of this chapter I present a survey of a representative selection of measures developed primarily for use with dementing patients. Because some of these measures are multipurpose batteries, it is not a simple matter to classify the range of standardized inventories available in terms of either content or function. Some measures are designed to be administered as tests of the instrumental skills of patients, others are based on relatives’ ratings, or on the observations of a trained interviewer. Accordingly, the categorization of measures presented here, which is based largely on test function, must be regarded as somewhat arbitrary.

Mental Status Examinations

The initial clinical examination of psychiatric or neurological clients often involves asking a set of relatively standard questions designed to screen for the presence of an acquired impairment in cognition. A number of these lists of mental status questions, which focus primarily on memory and orientation, have been published and have found widespread use in clinical and research practice. Usually the items employed in mental status examinations involve simple cognitive operations, well within the capability of the healthy elderly person, and failure on one or more of the test items raises the question of dementia. A typical set of items that might be used to assess mental status in dementing patients is presented in Table 1.1.

Table 1.1: Items Frequently Used to Assess Mental Status in Dementing Patients

Orientation
Time (year, season, date, day, month)
Place (“Where are we?,” city, town, hospital, ward)
Person

Concentration and attention
Serial sevens (count back from 100 in 7s)
Counting from 1 to 20
Counting from 20 to 1
Months of the year backward

Memory
Memory Span, repetition of digits (digit span)
Learn names of three objects (number of trials)
Delayed recall of same three objects (5-minute delay)

Remote Memory
Date of birth, place of birth, schools attended, occupation
Names of siblings, wife, and children
Names of employers
Name of mayor, president, date of World War 2
Knowledge of current events

Abstract thinking
Explain proverbs (e.g., “Don't cry over spilled milk.”)
Similarities (e.g., lion - tiger)

Language
Name common objects (pen, book, coin)
Repeat a complex sentence
Follow a three-stage command

Apraxia
Copy a geometric design

Orientation for place, person, and time is almost always tested in the course of a mental status examination. Some general knowledge or informational items, which assess remote memory for autobiographical information (“When did you go to school?”) or public events (“Who was the president of the United States during World War 2?”), are also usually included. Memory performance is particularly sensitive to the effects of dementia, and the failure to remember three or more items or paired-associates after a delay of up to 5 minutes, is suggestive of impairment. Concentration and attention is often tested by having the client count backward from a fixed number in threes or sevens. Another test often regarded as assessing concentration is repetition of strings of digits, a measure of memory span. The Digit Span subtest from the Wechsler Adult Intelligence Scale (WAIS) is often used for this purpose. Some examinations also include brief measures of constructional abilities, language, and abstract thinking.

Mental status tests vary considerably in length and in the range of abilities tested. The focus is on assessing cognition using verbal questions, although sometimes performance skills (copying or writing) are screened. The main use of mental status questionnaires is to screen for dementia in the clinic, or to provide evidence for the presence or absence of dementia in research samples. The items are relatively easy, thus these brief assessments do not provide a good documentation of the neuropsychological impairments in mildly demented patients. They may, however, be useful in characterizing the severity of dementia in patients whose impairment is in the moderate range. In addition, such measures are often the only way of assessing the residual capacity of moderately to severely demented patients. In sum, mental status tests will be most successful when used to distinguish patients with moderate impairments from healthy controls; at the early stages of a disorder like Dementia of the Alzheimer's type (DAT), classification based on mental status testing tends to be less accurate (Fillenbaum, 1980).

Table 1.2 lists some of the mental status examinations in general use. This list includes measures that provide brief assessments of a range of cognitive functions. Comprehensive batteries, comprising neuropsychological tests that are more sensitive to subtle changes in cognition (e.g., Dementia Assessment Battery; Teng et al., 1989) are considered later.

One of the most popular dementia screening tests is the Mini Mental State Examination (MMSE; M. F. Folstein, S. E. Folstein, & McHugh, 1975). This measure evaluates a variety of cognitive functions and has a score range of 0-30. The test-retest reliability of the MMSE is in the region of .8 - .95 (J. C. Anthony, LeResche, Niaz, Von Korff, & M. F. Folstein, 1982; Dick, Guiloff, Stewart, Blackstock, Bielawska, Paul, & Marsden, 1984; M. F. Folstein et al., 1975). The sensitivity of this examination to dementia is good, despite its brevity. For example, J. C. Anthony et al. (1982) found that 87% of a group of clinically diagnosed demented patients were correctly detected using a cutting score of 23 and below as indicating dementia.

Table 1.2: Standardized Mental Status Measures Used With Dementing and Geriatric Patients

Scale	Content
Mental Status Questionnaire (Kahn et al., 1960)	Orientation, information, calculation
Information-Memory-Concentration test (Blessed et al., 1968)	Orientation, information, attention
Mini Mental State Examination (M. F. Folstein et al., 1975)	Orientation, registration, attention, calculation, memory, language, copying
Short Portable Mental Status Questionnaire (Pfeiffer, 1975)	Orientation, attention, information
Clifton Assessment Scale (Pattie & Gilleard, 1975)	Orientation, information, concentration, writing, reading, psychomotor performance
Dementia Rating Scale (Mattis, 1976)	Orientation, attention, initiation and perseveration, construction (copying), conceptualization, memory
Alzheimer's Disease Assessment Scale (Rosen et al., 1984)	Orientation, memory, language, construction
Extended Mental Status Questionnaire (Whelihan et al., 1984)	Orientation, information, calculation, remote memory
Cambridge Cognitive Examination (CAMCOG; Roth et al., 1986)	Orientation, language, memory, construction skills, attention, abstract thinking, perception, calculation
Severe Impairment Battery (SIB; Saxton et al., 1990)	Orientation, social interaction, visuo-perception, construction, language, memory, praxis, attention

The sensitivity of the MMSE does, however, decline noticeably when mildly impaired patients are tested. Kay, Henderson, R. Scott, J. Wilson, Rickwood, and Grayson (1985) found that classification accuracy fell to 59% when the test was used to detect mild dementia. Similarly, Galasko, Klauber, Hofstetter, Salmon, Lasker, and Thal (1990) reported that the MMSE correctly detected only 50 of 74 community-dwelling demented patients, using a cutoff score of 23. Galasko et al. (1990) found that the sensitivity of the MMSE...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Part I Assessment
• Part II Neuropsychological Research
• Part III Psychosocial Aspects
• References
• Author Index
• Subject Index