Understanding the neuropsychological syndrome of dementia.

The syndrome of dementia is most commonly caused by Alzheimer's disease (AD), an age-related neurodegenerative process that primarily affects the cortex. Approximately 4 million Americans carry the diagnosis, and the number is expected to rise to 14 million by the year 2040. Affected individuals suffer multiple cognitive deficits that progressively affect the ability to communicate. Typically the earliest symptom is impairment of episodic memory, but other forms of declarative memory are ultimately impaired. To understand the communication problems of individuals with Alzheimer's, clinicians need to understand disease effects on knowledge stores and cognitive and memory processes. Using spared memory systems and less effortful cognitive processes to compensate for impaired stores and processes is the primary means by which optimal care can be provided. Recent advances in our understanding of disease effects on semantic memory suggest a greater potential for habilitation than previously thought. In this article, the neuropathology of AD is reviewed, effects on cognitive and communicative functions are specified, and principles for providing optimal patient care are discussed.

Retained neuropsychological abilities of individuals with Alzheimer's disease.

Individuals with Alzheimer's disease (AD) retain certain cognitive abilities over the course of the disease. In this article, we describe retained cognitive-linguistic abilities and the status of activities of daily living (ADLs) of individuals in the early, middle, and late stages of AD. Knowledge of preserved abilities in AD is necessary for clinicians to structure communication-stimulation programs and to train caregivers in the most effective ways to facilitate communication. Using the Global Deterioration Scale (GDS) for staging severity of AD, an outline of preserved abilities by disease stage is provided. Attention, memory, and communication abilities are discussed, and samples of discourse from patients at different stages are included.

Communication abilities of individuals with late-stage Alzheimer disease.

The communication abilities of 49 individuals in the late stage of Alzheimer disease were examined in relation to other markers of late-stage Alzheimer disease (e.g., incontinence and ambulatory ability). Two existing tools used to stage severity of dementia, the Global Deterioration Scale and the Functional Assessment Stages, have represented communication abilities in individuals with late-stage Alzheimer disease to be minimal to nonexistent. The individuals in this sample showed greater communication skills and verbal output than would be predicted by these scales.

Gender differences in language of Alzheimer disease patients revisited.

Results of recent investigations suggest that Alzheimer disease (AD) has a more deleterious effect on language in women than in men. This intriguing finding motivated an analysis of the language performance of probable AD patients, equally divided as to gender, on a variety of language comprehension and production tests. Cross-sectional data were available for 63 probable AD subjects and longitudinal data were available for 26. In addition to analysis of covariance used with the cross-sectional data, effect sizes were calculated. The longitudinal data were analyzed with repeated-measures analyses of covariance. The sum of scores on the orientation items of the Mini-Mental State Examination was used as the covariate in both analyses. No significant differences between the performance scores of male and female subjects were obtained for either the cross-sectional or longitudinal data. All effect sizes of gender were relatively small, with female patients outperforming males on most language tests. Results are discussed in the context of previous findings and comparison of the effect sizes among studies.

Performance of Alzheimer's disease patients in judging word relatedness.

Sixty individuals with probable Alzheimer's disease (AD) and 48 normal elders were given a task in which they had to judge the relatedness of concepts as a means of evaluating semantic memory. Very mild AD patients performed similarly to normal elders. Mild AD patients were significantly inferior in performance to normals but the pattern of their performance did not suggest a loss of conceptual knowledge. Moderate AD patients were significantly inferior in performance to mild AD patients, and 8 moderate AD patients (compared to 1 mild AD patient) were unable to do the task. The pattern of performance of moderate patients suggests that conceptual knowledge may degrade and ultimately be lost.

Comparing the difficulty of letter, semantic, and name fluency tasks for normal elderly and patients with Parkinson's disease.

Research on the effect of Parkinson's disease (PD) on verbal fluency has produced conflicting results. In this study, 88 PD patients with no dementia, 11 PD patients with questionable mental status, 15 PD patients with dementia, and 46 elders free from mental disorder were administered a variety of semantic, letter, and name fluency tasks. The results revealed that, contrary to popular assumption, semantic fluency was not always superior to letter fluency. Rather, verbal fluency was influenced by the nature of the individual categories. Interestingly, the relative difficulty of many categories was fairly stable across groups. The results also indicated that the individual fluency tasks were differentially sensitive to the mental status of the PD patients. Overall, the findings suggest that closer attention to the nature of the tested categories may help clarify the inconsistent effects of PD on verbal fluency.

Change in cognitive function in idiopathic Parkinson disease.

OBJECTIVE: To study the effects of Parkinson disease (PD) on cognitive function by determining the frequency and amount of change in Mini-Mental State Examination (MMSE) performance. DESIGN: During a 4-year period, 77 patients with idiopathic PD and 43 normal elders were administered a neuropsychological test battery twice at 2 years apart. RESULTS: A 4-point score difference on the MMSE was the amount that was statistically calculated to be a significant difference at the .05 probability level. Using this metric, 17 (22%) patients with PD had a change in their MMSE performance during a 2-year period. Fifteen individuals performed poorer, and 2 individuals improved. Using the same metric, no normal subjects changed in their MMSE performance. The groups of patients with PD who had a change and did not have a change in their MMSE performance were not characterized by significant differences in their years of education, duration of illness, age at onset, age at test time 1, estimated premorbid intelligence, Hamilton Psychiatric Rating Scale for Depression score at test time I, or Unified Parkinson's Disease Rating Scale score. The singular difference was the higher frequency of change that was found in subjects who were taking dopamine agonists at the second test time. CONCLUSION: A change in cognitive function in patients with PD, as measured by a change of 4 points or more in their MMSE performance, was observed in only 22% of a sample of 77 patients with idiopathic PD during a 2-year period.

Phrase repetition in Alzheimer's disease: effect of meaning and length.

Repetition ability depends in part on the intactness of semantic memory. If the conceptual contents of semantic memory are lost as a function of Alzheimer's disease (AD) pathology, meaningfulness of stimuli should have progressively less effect on the ability to repeat as the disease worsens. This study was designed to evaluate the effects of meaningfulness and length of phrasal stimuli on repetition ability in mild and moderate AD patients and normal elderly subjects. Fifty-seven AD patients and 52 normal subjects were given six- and nine-syllable phrases that were meaningful, improbable in meaning, or meaningless. Cross-sectional and longitudinal data analyses were conducted and results failed to confirm a performance pattern consistent with a semantic memory loss theory. Meaningless nine-syllable phrases were those most difficult to repeat for moderate as well as mild AD patients and normal controls.

Category and attribute knowledge deterioration in Alzheimer's disease.

A prevalent theory regarding the deterioration of semantic memory in Alzheimer's disease is that it is a bottom-up process. If this is true, performance on tests of attribute knowledge should decline more rapidly than performance on tests of categorical knowledge as dementia severity increases. In the present study, a convincing pattern of findings to either support or reject the theory failed to emerge. This raised questions regarding the ability to separate attribute and categorical knowledge, and whether one can be tested without influence of the other. Questions also were raised regarding the additional cognitive processes needed to complete tasks of semantic memory.

Use of the Arizona Battery for Communication Disorders of Dementia in the UK.

The Arizona Battery for Communication Disorders of Dementia (ABCD) (Bayles & Tomoeda, 1993) was given to groups of young and old normal subjects and to subjects with moderate Alzheimer's disease in the UK. Very few significant differences were found between their raw scores and those of the original standardisation sample in the USA, which makes the ABCD an appropriate test to use in the UK. Although some subjects commented on several of the test stimuli, cultural differences in pictures and vocabulary did not produce notable effects on test performance and so alterations to test materials are not required for the test to be used in the UK.

Cross-sectional analysis of Alzheimer disease effects on oral discourse in a picture description task.

To examine the relation of dementia severity to the quality and quantity of oral discourse of individuals with Alzheimer disease (AD), a picture description task was administered to elicit oral discourse samples from 63 AD subjects, five individuals with very mild cognitive impairment, and 52 normal controls. Eight measures of discourse were used: total words, information units, conciseness, circumlocutions, frustrations, aborted phrases, revisions, and ideational repetitions. Information units, which decreased with increased dementia severity, proved to be the best measure for evaluating the effects of AD on oral descriptive discourse. The conciseness index also decreased with increased dementia severity, and a significantly greater proportion of AD discourse samples contained ideational repetitions. Circumlocutions and frustrations rarely occurred, and although the discourse of AD subjects was more likely to contain an aborted phrase, the frequency of aborted phrases did not vary by stage of dementia. Revisions were commonly observed in the discourse of both normal controls and AD subjects and did not differentiate the two groups.

Memory impairment and executive control in individuals with stroke-induced aphasia.

The purpose of this study was to examine memory abilities of aphasic individuals in relation to site of neurological lesion. Fourteen individuals with stroke-induced aphasia (7 with anterior lesions; 7 with posterior lesions) and 14 demographically matched control subjects were given selected tests of short-term memory (STM) and long-term memory (LTM). Stroke patients were impaired relative to control subjects on tests of verbal memory, with greater impairment of LTM associated with anterior lesions and greater impairment of STM associated with posterior lesions. Verbal memory performance did not correlate highly with language ability, and did not appear to be simply a consequence of language impairment. Executive control deficits were postulated as explanatory of the LTM impairment associated with anterior lesions.

Generative naming in Parkinson disease patients.

The generative naming ability (verbal fluency) of 88 idiopathic Parkinson disease (PD) patients was evaluated and compared to that of 21 Alzheimer disease (AD) patients and 43 normal age- and education-matched normal control subjects. The PD patients were classified according to whether they scored within the normal range on the Mini-Mental State Examination (MMSE), a score of 27 or higher, or in the abnormal range, a score of 26 or lower. Semantic and letter generative naming tasks were administered to assess verbal fluency. Results of the study provide evidence that letter category naming is inherently more difficult than semantic category naming; that age significantly affects generative naming; that PD patients with normal MMSE scores were significantly inferior to normal control subjects in generative naming even after the effects of age and mental status are controlled; that PD patients with non-normal MMSE scores performed like AD patients after controlling for the effects of age and mental status; and, that ideational perseveration is the most common type of error response for all subject groups.

Longitudinal effects of Alzheimer disease on discourse production.

As part of a 5-year study of the longitudinal effects of Alzheimer disease (AD) on language, discourse samples from three patients diagnosed with AD and three matched normal controls were analyzed. A picture-description task was used to elicit comparable samples of discourse. Subjects were asked to describe the "Easter Morning" picture by Norman Rockwell. Samples were tape recorded, transcribed, and scored using eight measures of discourse production. These measures successfully quantified the changes in quantity and quality observed in the discourse of AD patients over time. Results revealed remarkably similar patterns, adding a longitudinal dimension to the growing body of knowledge of the effects of AD on discourse production.

Confrontation naming in Alzheimer's patients: relation to disease severity.

Reports of Alzheimer's disease patients in whom naming performance is disproportionate to other cognitive performances raise questions about the stage model, or dementia-severity level, for predicting naming performance. Thus, dementia severity as defined by Global Deterioration Scale ratings, Mini-Mental State Examination scores, and combinations of them was evaluated as a predictor of naming performance in 102 Alzheimer's patients and was found to account for approximately 1/3 of performance variability. Additional contributions from age at onset, duration, family history, and gender were negligible. Therefore, naming ability can be argued to have a subcomponent that is not subsumed by overall cognitive ability.

Relation of linguistic communication abilities of Alzheimer's patients to stage of disease.

A battery of linguistic communication (L-C) tasks was administered to 152 Alzheimer's disease patients in different stages of the disease and 60 normal elders. Subject performance data are used to construct a profile of L-C deficits by disease stage, as determined by ratings on the Global Deterioration Scale. Specification also is made of the L-C tasks on which mild Alzheimer's patients perform like normal elders, the relative difficulty of various L-C processes, the disease stage in which the greatest change occurs in L-C functions, and the degree of variation in L-C for individuals at a particular level of dementia severity.

Acquired mutism: physiopathy and assessment.

The speechless patient presents a unique challenge to the clinician working with neurologically impaired adults. Acquired speechlessness, or mutism, has been associated with a variety of clinical states and syndromes after damage to central and peripheral nervous system structures. The intent of this paper is to summarize the reported states and syndromes associated with acquired mutism (eg, persistent vegetative state, akinesia), and to organize this information in a framework for clinical assessment of the speechless patient. For the purpose of discussion, speech production is divided into five interrelated processes: arousal; cognitive processing; affect and drive; motor initiation, planning, programming, and coordination; and execution of movement. Disorders characterized by mutism are classified according to the process or processes of speech production that primarily are affected. Each subtype of acquired mutism is characterized by a cluster of neurologic signs, which has been incorporated into a decision-making framework for use in a clinical setting.

Caregiver report of prevalence and appearance order of linguistic symptoms in Alzheimer's patients.

We interviewed primary caregivers of 99 Alzheimer's disease patients about the existence and appearance order of linguistic symptoms in a longitudinal study of disease effects on communication. The most prevalent linguistic symptom was difficulty finding the correct word and the least prevalent was increased talkativeness. The prevalence of linguistic symptoms was strongly correlated with order of symptom appearance, with difficulty writing a meaningful letter appearing first and word finding difficulty appearing second. Based on caregiver perceptions, symptom prevalence and order of appearance are specified and discussed in relation to onset of nonlinguistic memory deficit, dementia severity, and performance on a linguistic communication test battery.

Age at onset of Alzheimer's disease. Relation to language dysfunction.

A later age at onset of Alzheimer's disease (AD) was found to be related to diminished language performance in 86 patients with probable AD. A hierarchical linear model was constructed to assess effects of age at onset and disease duration on the performance of patients with AD on four language tasks (naming, reading, auditory comprehension, and writing to dictation) after controlling for disease severity. Results of univariate analysis, in which the dependent variable was the averaged language task performances, revealed a significant effect for age at onset of AD, but not for disease duration. To assess the possibility that the relationship between the age at onset of AD and language performance reflects effects of normal aging, the language tasks were given to 33 normal subjects of similar ages who scored perfectly on dementia severity measures. A convincing relationship was not found between test score and age.

Alzheimer's disease effects on semantic memory: loss of structure or impaired processing?

Results of several prior studies, in which Alzheimer's disease (AD) patients missed the same concepts on multiple tasks, have been used to substantiate the theory that AD causes concept-specific loss of information from semantic memory However, sample sizes in these studies are modest, test-retest intervals small, and typically only a few tasks were used. In the present study 69 An subjects were annually administered 11 tasks, each using the same 13 concepts. Only a few instances were observed in which a concept was missed across all 11 tasks. When performances on the Oral Reading and Dictation tasks were removed from analysis, because of their questionable reliance on semantic memory, the number of missed concepts rose only modestly. A substantial rise in the number of missed concepts occurred, however, when performances on the four multiple- choice tasks were removed. Interpreting the larger number of missed concepts on the five remaining generative semantic tasks as evidence of item-specific loss is problematic, nonetheless, because the generative semantic tasks were among the hardest in the battery and the frequency with which an individual subject missed a concept across all tasks accorded with the subject's dementia severity level. Results also indicate that task difficulty, more than concept specificity, determine whether a concept is missed. Overall, results suggest that a concept will "disappear" when all of the tasks in which it is a stimulus become too difficult for the patient to perform. Study results call into question the appropriateness of using batteries of effortful, attention demanding tasks for ascertaining whether AD causes item-specific loss of conceptual knowledge.