Primate learning tasks reveal strong impairments in patients with presenile or senile dementia of the Alzheimer type

Eight subjects with the likely diagnosis of presenile or senile dementia of the Alzheimer type were tested on two frequently used primate learning tasks: a concurrent object discrimination task and a delayed non-match-to-sample task. In addition, various tests for cognitive, mnemonic, perceptual, and language functions were applied. The results suggest a severe decline of the Alzheimer subjects in all measures when compared with 10 control subjects matched for age, gender, and education. The two animal learning tasks revealed strong impairments, thus demonstrating a high sensitivity for the detection and assessment of human amnesic disorders. Implications of these findings for human neuropsychological, and especially comparative neuropsychological, research are discussed.     

Articulatory rehearsal in Alzheimer type dementia

This study investigated the relationship between articulation rate and memory span in a sample of 21 patients with early Alzheimer type dementia (AD), comparing their performance with 21 matched controls. Memory span was measured using auditorily and visually presented digits. The AD patients were moderately impaired in both conditions. Articulation rate was measured either by requiring subjects to read lists of random digits or repeatedly count from 1 to 10. The AD patients were able to read the digits as fast as the controls but were slower in the counting task. The measures of memory span and articulation rate correlated significantly for the controls but not for the AD patients, indicating that the normal association between articulation and memory span is disrupted. These results are discussed in relation to previous results and suggest that articulatory rehearsal processes in primary memory are unimpaired at the early stages of AD.     

Language disorders in dementia of the Alzheimer type

The language profile of a group of 18 Alzheimer patients is documented and their performance on a standard aphasia test battery compared to a group of institutionalized, nonneurologically impaired control subjects matched for age, sex, and educational level. The Alzheimer patients scored significantly lower than the controls in the areas of verbal expression, auditory comprehension, repetition, reading, and writing. Articulation abilities were the same in each group. A language deficit was evident in all Alzheimer patients. The language disorder exhibited resembled a transcortical sensory aphasia. Syntax and phonology remained relatively intact but semantic abilities were impaired. The results support the inclusion of a language deficit as a diagnostic criterion of Alzheimer's disease.     

Lexical therapy and episodic word learning in dementia of the Alzheimer type

The effect of a language therapy in a group of eight anomic mild patients (the Lexical Therapy group) was assessed by using a 5-month long Lexical Therapy in comparison with an occupational program used in a matched control group (AD; n = 8). The Lexical Therapy group benefited significantly from a language therapy as shown by the naming improvement postintervention. The improvement reached significance only for items that were included in the language therapy protocol and no significant generalization to untreated items was observed. In mild AD patients with anomia and no severe semantic impairment, a reinforcement of the relationship between the form of the object and the corresponding lexical label in episodic long term memory during language therapy may account for the observed lexical improvement.     

Event understanding and memory in healthy aging and dementia of the Alzheimer type

Segmenting ongoing activity into events is important for later memory of those activities. In the experiments reported in this article, older adults' segmentation of activity into events was less consistent with group norms than younger adults' segmentation, particularly for older adults diagnosed with mild dementia of the Alzheimer type. Among older adults, poor agreement with others' event segmentation was associated with deficits in recognition memory for pictures taken from the activity and memory for the temporal order of events. Impaired semantic knowledge about events also was associated with memory deficits. The data suggest that semantic knowledge about events guides encoding, facilitating later memory. To the extent that such knowledge or the ability to use it is impaired in aging and dementia, memory suffers.     

Semantic abilities in dementia of the Alzheimer type. 1. Lexical semantics

The lexical semantic abilities of 18 Alzheimer patients were investigated using confrontation naming tasks (including both visual and tactile naming tests) and compared to those of a group of institutionalized, nonneurologically impaired control subjects matched for age, sex, and educational level. The Alzheimer patients produced a greater number of naming errors than the control subjects. The errors made by subjects during the naming tasks were analyzed according to a set of 16 error response types. The Alzheimer patients' response patterns suggest that they do recognize objects which they are unable to name and are able to identify the semantic class to which the target belongs, but cannot provide the lexeme corresponding to the correct individual class member. The results support a semantic network disruption rather than a visual perceptual deficit as the basis of the naming disturbance observed in Alzheimer patients.     

Semantic priming effects, lexical repetition effects, and contextual disambiguation effects in healthy aged individuals and individuals with senile dementia of the Alzheimer type

An experiment is reported that addresses semantic priming effects, lexical repetition effects, and the influence of context on meaning selection for ambiguous words in 32 healthy aged individuals and 32 individuals with Senile Dementia of the Alzheimer Type (SDAT). On each of 232 trials, subjects pronounced each of three words. The four major conditions were concordant (music-organ-piano), discordant (kidney-organ-piano), neutral (ceiling-organ-piano), and unrelated (kidney-ceiling-piano). In order to address lexical repetition effects, target words were repeated across Blocks 1 and 2 but not in Block 3. Analyses of naming latencies indicated that semantic priming effects and lexical repetition effects were slightly larger in SDAT individuals than in healthy aged individuals. More importantly, healthy aged individuals produced normal selective access of the contextually biased meaning whereas SDAT individuals produced evidence consistent with nonselective meaning access. These results are discussed within both an attentional and a connectionist account of homograph disambiguation.     

The pattern of reading deterioration in dementia of the Alzheimer type: Observations and implications

Thirteen patients with dementia of the Alzheimer type (DAT) were tested for their ability to read aloud and to read with comprehension. Reading aloud was preserved in all but the most severely impaired cases and was found to be relatively independent of intellectual deterioration. Reading comprehension declined progressively with increasing dementia severity and correlated well with quantitative mental status assessments. The results suggest that the pattern of reading deterioration may aid in the clinical identification of DAT, that the disturbance of reading comprehension is a linguistic deficit rather than a product of visual-perceptual disturbances, and that the alexia is more consistent with an instrumental loss than a de-developmental model of dementia.     

Response consistency on a semantic memory task in persons with dementia of the Alzheimer type

The purpose of this investigation was to determine the test-retest response consistency rate on a semantic memory task in persons with dementia of the Alzheimer type (DAT). Ten mildly and 13 moderately impaired DAT subjects and 14 normal controls matched for age, years of education, and estimated IQ participated in this study. The Peabody Picture Vocabulary Test (PPVT) was administered twice to each subject with a 7-day intertest interval. The mild and moderate DAT subjects responded inconsistently to significantly more PPVT items than normal controls. When the effects of guessing were considered, moderate DAT subjects gave significantly more inconsistent PPVT responses than normal controls and mild DAT subjects showed a trend toward giving more inconsistent responses. These results substantiate the conclusion that the impairment of specific conceptual knowledge in DAT subjects cannot be reliably measured with a single administration of a semantic memory task such as the PPVT.     

Turn-taking and speech act patterns in the discourse of senile dementia of the Alzheimer's type patients

Conversational discourse patterns of 11 normal elderly and 11 senile dementia of the Alzheimer's type (SDAT) patients engaged in dyadic interaction with an examiner were examined. Differences in word usage, turn taking, and speech act production were investigated both for the two-subject groups and for the examiner's conversations with each group. Compensatory shifts in discourse by participants are identified. For the subject, differences were shown on words per turn with SDAT subjects speaking in shorter turns and in nonverbal responses with SDAT subjects using this strategy more frequently. Speech act categories of Requestives and Assertives also differed with SDAT subjects using more Requestives and fewer Assertives. The SDAT subjects had significantly more occurrences of unintelligible utterances. For the examiner, words per turn differed with the examiner using shorter turns with SDAT subjects. No differences were shown in the examiner's patterns of speech act usage, nonverbal responses, or intelligibility. In general, these results indicate significant discourse differences in the words per turn level for all participants and speech act levels of conversation for SDAT subjects. They also indicate generally maintained interaction patterns by speakers so that the discourse genre of conversation is sustained. The pattern of compensatory shifts in discourse suggests retained flexibility in the communication system of early and mid stage SDAT patients.     

Effects of attention on dichotic listening in elderly and patients with dementia of the Alzheimer type

This article presents an overview of our studies in elderly and Alzheimer patients employing Kimura's dichotic digits paradigm as a measure for left hemispheric predominance for processing language stimuli. In addition to structural brain mechanisms, we demonstrated that attention modulates the direction and degree of ear asymmetry in dichotic listening. Elderly showed increasingly more difficulties focusing attention on the left ear (LE) with advancing age. Alzheimer patients showed severe deficits to allocate attention to the LE, which could result in a right ear advantage. These results may be attributed to a breakdown of the cortical attentional network which is mediated by frontal (inhibitory control of attention) and parietal regions (spatial attention and 'disengagement processes'). Both interhemispheric disconnectivity (callosal atrophy) and intrahemispheric disconnectivity (subcortical white matter lesions) appear to be important factors contributing to these findings.     

Variations of the Bender-Gestalt Test: implications for training and practice

Although the Bender-Gestalt Visual Motor Test has been a popular and influential clinical assessment instrument for the last half century, authoritative opinion and a substantial research literature are often inconsistent or contradictory. This paper documents variations in designs, administration procedures, forms, and applications to particular populations. A careful review of scoring systems indicates the current status of objective approaches as contrasted with interpretation that is global, intuitive, and subjective. Some implications of these variations and interpretive procedures for training and assessment practice are discussed. The major conclusions of the review are summarized in seven points.     

Investigating visual knowledge in dementia of the Alzheimer type (DAT): evidence for a structured organization

Given that certain types of semantic dysfunction in DAT have been attributed to difficulties in accessing visual knowledge, the issues of integrity of access to, and format of storage, within the "visual store" are particularly important. In these experiments, we tested 10 DAT patients and matched controls on the reality decision and part-whole matching tasks. Visual knowledge was found to be significantly impaired in the DAT group. Moreover, DAT patients displayed disproportionate deficits in accessing visual knowledge of items from nonliving categories. Results are interpreted within a framework of differential hierarchical access to visual representations of perceptually similar and perceptually distinct categories of items.     

Psychopathology scale of the Hutt adaptation of the Bender-Gestalt Test: reliability.

The test-retest reliability of the Hutt Adaptation of the Bender-Gestalt test was explored with a population of 40 process schizophrenics over a two-week interval. The total Psychopathology Scale Score was found to have high retest reliability for both male and female patients (rho = .87 for males and .83 for females). Moreover the three major components for the Scale were found to have high reliability, and fairly high reliabilities were obtained for patients scoring high as well as low on the Scale. Interjudge reliability was also found to be very high (rho = .895), confirming previous studies in this respect. On these grounds, the Scale offers promise both for clinical and research purposes.