An Italian series of patients with organic dementia

Working memory and vigilance: evidence from normal aging and Alzheimer's disease

Both single unit recording and neuroradiological studies suggest that frontal and executive processes are necessary for visual maintenance rehearsal. This observation is linked to the classic vigilance literature by the proposal that vigilance decrement is found when the subject is required to maintain a representation over a brief delay. Vigilance performance was therefore studied in a sample of elderly subjects who were tested over a 40-min period involving perceptual or memory-based tasks which were matched for initial level of performance. There was a significant interaction between task and delay, with only the memory-based task showing decrement. A second study used the same two tasks to investigate vigilance performance in patients suffering from probable Alzheimer's Disease. Over a 15-min delay period, an equivalent interaction effect occurred, again indicating substantially greater decrement for the memory-based task. The results are interpreted as consistent with a role for the executive processes of working memory in both visual rehearsal and vigilance performance.

Alzheimer patients show a sensitivity decrement over time on a tonic alertness task

Tonic alertness was investigated in Alzheimer patients and normal elderly subjects. Sensitivity and criterion shifts were investigated across 45 min of continuous testing using a high event rate test with very low target probability. Alzheimer patients showed a significant sensitivity decrement over time that was unrelated to dementia severity. These results suggest that tonic alertness is impaired by Alzheimer's disease even in its early stages.

Autobiographical recollection and frontal damage

A neuropsychological experiment on autobiographical retrieval of incidental past events, checked by means of a standardized enquiry, was carried out on a series of 16 patients with CT-assessed frontal lobe lesions. Of 16 patients, six were impaired on autobiographical retrieval. Moreover, eight were impaired on supraspan verbal learning. Impairment on both resulted in three patients, whereas in five there was no impairment on either test. Concordance between autobiographical and learning impairment was far from significant. Poor autobiographical retrieval correlated significantly with "executive" test performances and with the CT-verified bilaterality of the frontal damage. Poor learning of new information did not correlate significantly with "executive" performances, nor did it appear to be related to the hemispheric side or to the bilaterality of the frontal lesion. We propose that the relationship between the attentional system of retrieving from remote memory and of learning new information is qualitatively different.

Study of the language functions controlled by the right hemisphere in patients affected by dementia

An insertion test (Shift vs. non-Shift) was performed by eight subjects (mean age 69 years, mean schooling 5.87 years) with clinical diagnosis of suspected Alzheimer disease (AD) in order to reveal right hemisphere cerebral distress in concomitance with damage of the left hemisphere which controls language in AD. Their Shift and non-Shift test scores were significantly lower than those of 28 controls, even if they achieved normal or slightly modified classical language test scores. Shift involves insertion of a syntagma or word in a stimulus-sentence that changes the syntactical relationship of some components of the newly formed sentence, whereas in non-Shift the insertion determines only a change in meaning. Statistical analysis revealed that the difference was not caused by age and schooling. Furthermore, the AD patients achieved significantly lower scores in Shift compared with non-Shift. This indicates greater right hemisphere damage in these patients and confirms its physiological decline in the elderly. The results revealed that the insertion test is more sensitive than classical neurolinguistic tests. They also showed that both superficial (non-Shift) and deep (Shift) types of syntaxes are already compromised in early stages of AD and that they mirror the bilateral thinning which is more pronounced in the right hemisphere.

A cancellation test: its reliability in assessing attentional deficits in Alzheimer's disease

The aim of the study is to provide (i) a standardized procedure for a Cancellation Test of Digits, designed to assess in the visual modality selective attention deficits in patients with Alzheimer's disease, and (ii) a detailed analysis of how patients cope with it. Age-, education-, and sex-adjusted normative scores earned by 352 healthy controls are set forth, as well as data yielded by the Digit Cancellation Test in 74 Alzheimer patients, in 26 patients with a CT-assessed frontal lobe lesion and in a group of 24 healthy subjects urged to perform the task with a shortened time-constraint. Findings include discriminant power of Alzheimer patients versus healthy controls, sensitivity to cognitive evolution of the dementing process and analysis of errors. Attention data failed to supply psychometric support for the posterior-to-anterior algorithm of progressive cortical encroachment of Alzheimer's disease suggested by PET-findings. Emphasis is put on methodological aspects of neuropsychological research on Alzheimer patients and on the analysis of processing components of the tests employed. Results are discussed in the light of the relationships between psychometric assessments and related functions, and underlying neuronal degeneration.

Recency, primacy, and memory: reappraising and standardising the serial position curve

In this paper we consider the serial position curve in immediate verbal free recall. A large literature has argued that two components of the serial position curve, recency and primacy, reflect the functioning respectively of short-term and of long-term memory. However, there are a number of difficulties in interpreting the recency effect as a phenomenon uniquely associated with short-term memory. Moreover, the serial position curve has been used widely for clinical investigations in patients with memory deficits. This is despite the lack of norms for the measures derived from the curve. We present a set of standardised norms based on 321 Italian normal subjects. These norms are shown to be applicable both to an English speaking population, and to three groups of brain damaged-patients, namely Alzheimer's, amnesics, and frontals. The standardised norms offer a clinical and experimental tool which, coupled with a multiple single case approach, allows us to show dissociations and double dissociations among the performance patterns obtained from all three pathological groups. The paper concludes with a discussion of a possible interpretation of the recency effect as a emergent property of all types of memory system, including verbal short-term memory. Taking into account previous literature as well as our own data, the recency effect in immediate verbal free recall is here interpreted in terms of a two-component view of verbal short-term memory.

Mini-Mental State Examination (MMSE): sensitivity in an Italian sample of patients with dementia

The sensitivity of the Mini-Mental State Examination (MMSE) was assessed in a sample of patients with dementia of the Alzheimer type or vascular dementia. The MMSE identified the majority of pts with diffuse cognitive impairment but did not discriminate between the two types of dementia. If failed to detect mild deterioration or forms in which only some cognitive functions were impaired. The test is therefore not sufficient for distinguishing deteriorated from non deteriorated pts, although it is still useful in mass screening or for a quick assessment of deterioration in the course of clinical neurological examination.

The two-component hypothesis of memory deficit in Alzheimer's disease

Becker (1988) has argued that Alzheimer's disease is particularly characterised by a combination of amnesic and dysexecutive deficits. He has supported this hypothesis by identifying patients who represent a relatively pure example of each of these. We describe a search for similarly pure patients in a sample of 55 carefully selected Alzheimer cases. We succeed in identifying one case each of relatively pure amnesia and relatively pure dysexecutive syndrome. We also, however, find cases of predominant STM deficit, as well as cases with defective visual but not verbal memory, and cases of the converse pattern. These cases do not seem to reflect simple random variation in the data, since less theoretically coherent patterns of symptoms are not found in this pure form. We conclude that AD can give rise to relatively specific cognitive deficits during its early stages, but that these do not necessarily argue for Becker's two-component interpretation of the cognitive deficit in Alzheimer's disease.

Generative associative naming in dementia of Alzheimer's type

Forty-eight patients with mild to moderate dementia of Alzheimer's type (DAT) were tested with a generative associative naming task, a task that combines the aspects of fluency and of word association tests. The variables taken into consideration were the number of adequate and inadequate responses, conventionality, word frequency and lexical-semantic relation to the target. DAT patients' performances were compared to those of a group of control subjects matched for sex, age and educational level. As a group, the patients gave fewer adequate responses, more idiosyncratic responses and perseverations, while there was no difference in the qualitative variables. However, the analyses of the performance profiles suggest that, irrespective of the severity of the disease, two major subgroups of DAT patients may be identified: (1) a first subgroup of subjects produced words with a lower conventionality rate and these were mostly in propositional relationship to the target; they also produced a higher rate of idiosyncratic responses and perseverations. (2) A second subgroup of subjects gave more conventional responses, mostly in the hierarchical-categorical relationship. The disorders of the former subgroup seem to correspond to a disrupted access to some relatively spared semantic abilities, whereas those of the latter to a semantic breakdown.

Controversial neuropsychological issues in Alzheimer's disease: influence of onset-age and hemispheric asymmetry of impairment

A battery of 21 standardized neuropsychological tests was used in a retrospective study carried out on 52 mildly demented Alzheimer patients to analyse the relationship between age at onset of disease and the progress of cognitive impairment. Early onset was found to be associated with a more severe impairment. Possible sampling biases are discussed. Forty-seven patients were also tested for hemisphere asymmetry of cognitive impairment with two subsets of tests predominantly tapping left and right hemisphere abilities, respectively. We found a significant predominance of left-sided impairment which was not related to age at onset of disease. Possible relationship of this finding to healthy brain asymmetries is discussed.

Autobiographical memory. Its impairment in amnesic syndromes

Three groups of brain-damaged patients with severe anterograde episodic amnesia, manifest both ecologically and psychometrically, were tested with an autobiographical memory (ABM) inquiry for which age-education adjusted normal baselines were available. One group was made up of 19 patients in the early stages of Alzheimer's disease and the other of 12 "pure" amnesic patients, 6 of whom had focal diencephalic damage and 6 widespread brain damage. ABM information retrieval was severely impaired in 84% of the early-stage demented patients and in the "pure amnesics" with widespread brain damage, but much less in those with focal damage. No temporal gradient emerged in either group and confabulation was only a marginal factor. Poor performances of demented and nonfocal amnesics were attributed to inertness in the search process.

Selective visual attention in Alzheimer's and Parkinson's patients: memory- and data-driven control

An automated visual search experiment was carried out on patients with incipient Alzheimer's disease, non-demented Parkinsonians and healthy controls to test for selective attention control within the framework of the Norman and Bobrow (1975) model. The performances of the Parkinsonians and healthy controls were consistent with the predictions of this model but those of the Alzheimer patients were not. These patients appeared to be no longer sensitive to the facilitation supplied by the stimulus context and to spend most of their residual resources on achieving accuracy. The reduction of their attentional resources possibly interferes with the control of the speed-accuracy trade-off.

Progressive language impairment without dementia: a case with isolated category specific semantic defect

A patient is described with a 5 year progressive defect of naming and auditory verbal comprehension, the pathological nature of which was presumably degenerative. The auditory comprehension defect unevenly affected different semantic categories, and was particularly severe for the names of animals, fruits and vegetables. The patients showed loss of the verbal knowledge of the physical attributes of the concepts corresponding to the words he was unable to understand, and sparing of the verbal knowledge of the functional attributes. His performance was defective also on the colour-figure and sound-picture matching test.

The role of clinical neuropsychology in the neurological diagnosis of Alzheimer's disease

This survey on the early diagnosis of Alzheimer's disease (AD) reinstates the role of clinical neuropsychology in describing the cognitive status of AD and its evolution. The role of clinical neuropsychology is restricted to the clinical diagnosis of organic mental deterioration and its contribution to the diagnosis of AD is separate from that of neurology and neuroradiology. The frequency of a single neuropsychological disturbance in early AD patients is illustrated by our own observations.

Problem solving ability of parkinsonians

The hypothesis to be verified is that the cognitive defects in nondemented and nondepressed Parkinsonians are due solely to a bilateral nigrostriatal disorder that causes motor slowing. It was tested on 26 mildly disabled patients with idiopathic Parkinson disease optimally controlled with L-Dopa, nondemented and nondepressed and not receiving anticholinergic. The test used was a simplified version of the London Towers Test of problem-solving ability, designed to measure a facet of prefrontally-induced bradyphrenia, already calibrated on 131 healthy subjects. The results revealed no significant difference between the Parkinsonians and controls, thus providing no support for the hypothesis in question.

Ideomotor apraxia in patients with dementia of Alzheimer type

Ideomotor apraxia was checked in a carefully selected group of patients with Alzheimer's dementia, all in the mild stage of the disease. It was shown that ideomotor apraxia is not an early neuropsychological feature. When compared with other cognitive measures, the speed of deterioration of ideomotor apraxia appears to be particularly slow.

Dementia and working memory

This study explored the hypothesis that patients suffering from dementia of the Alzheimer type (DAT) are particularly impaired in the functioning of the Central Executive component of working memory, and that this will be reflected in the capacity of patients to perform simultaneously two concurrent tasks. DAT patients, age-matched controls and young controls were required to combine performance on a tracking task with each of three concurrent tasks, articulatory suppression, simple reaction time to a tone and auditory digit span. The difficulty of the tracking task and length of digit sequence were both adjusted so as to equate performance across the three groups when the tasks were performed alone. When digit span or concurrent RT were combined with tracking, the deterioration in performance shown by the DAT patients was particularly marked.

Is there a specific visuo-spatial impairment in Parkinsonians?

Twenty-five non-demented patients with mild, idiopathic, Parkinson's disease were compared with 25 age and education matched normal controls on a visuo-spatial performance task, whose characteristics were directional forecast, with minimal motor requirement and a maximal spatial load. No statistical support was found for the existence of spatial impairment in these patients.