François Boller

Computerized EEG spectral analysis in elderly normal, demented and depressed subjects

Computerized spectral analysis of the EEG was performed in 35 patients with Alzheimers disease and compared to patients with major depression (23) and healthy elderly controls (61). Compared to controls, demented patients had a significant increase in the theta and alpha 1 bandwidths as well as an increased theta-beta difference. The parasagittal mean frequency, beta 1 and beta 2 activity were significantly decreased. Depressed patients differed from demented patients, particularly at the lower end of the spectrum, having significantly less delta and theta activity. Like the demented group, depressed patients also had a decreased parasagittal mean frequency, beta 1 and beta 2 when compared to controls. In demented patients, there was a high correlation between several spectral parameters (parasagittal mean frequency, delta and theta activity, and the theta-beta difference) and the Folstein score, EEG measures used for discriminant analysis were more accurate in identifying demented patients who had lower Folstein scores.

Neuropsychological prediction of dementia in Parkinson’s disease

OBJECTIVE To identify neuropsychological characteristics predictive of later dementia in Parkinson’s disease. METHODS A comprehensive neuropsychological test battery was administered to a cohort of 89 initially non-demented patients with Parkinson’s disease consecutively enrolled at a specialised Parkinson’s disease clinic. They were reassessed after a mean of 3.5 years for the diagnosis of dementia. The Cox proportional hazards model was used to identify baseline characteristics predictive of dementia. RESULTS Only four of the baseline clinical characteristics of Parkinson’s disease and neuropsychological variables remained independently linked to subsequent development of dementia: the age of onset of Parkinson’s disease (>60 years; relative risk (RR) 4.1, 95% confidence interval (95% CI) 1.8–24.0, p<0.03), the picture completion subtest of the Wechsler adult intelligence scale (score<10; RR 4.9, 95% CI 1.0–24.1, p<0.02), the interference section of the Stroop test (score<21; RR 3.8, p=0.08), and a verbal fluency task (score<9; RR 2.7, 95% CI 0.8–9.1, p=0.09). Depressive symptoms and the severity of motor impairment were not predictive of dementia. CONCLUSION These features are different from the neuropsychological characteristics predictive of Alzheimer’s dementia in healthy elderly people (mainly memory and language performance). They are in keeping with the well known specificity of the impairments in Parkinson’s disease for visuospatial abilities and difficulties in inhibiting irrelevant stimuli. It is postulated that the composite nature of the picture completion subtest, involving several cognitive abilities impaired in Parkinson’s disease, explains its sensitivity.

Use of semantic context by patients with Alzheimer's disease.

In this study we used semantic-priming procedures to examine limitations in the use of semantic context by patients with Alzheimers disease. We also tried to determine whether any such contextual effects were mediated solely through automatic processes or whether attentional processes were also involved. Three tasks were applied to examine the effect of semantic context on the performance of 18 normal elderly and 18 normal young subjects, and on 18 patients with Alzheimers disease. When normal and demented subjects were asked to decide whether a given item was a member of a certain category, results showed that their response times were equally affected by the items dominance in the category. The time that demented patients took to recognize a word was actually affected more by the semantic context provided by a priming sentence than was that of normal subjects. When asked to generate the final word of an incomplete sentence, demented subjects performed very poorly unless potential responses were highly constrained by sentence context.

Calculation disturbances in adults with focal hemispheric damage.

It has been suggested that hemisphere-damaged patients with calculation disorders can be subdivided into 3 groups: agraphia or alexia for numbers, spatial dyscalculia and anarithmetia. The purpose of the present study was to evaluate the role played by visuospatial disorders and by anarithmetia in subjects with impaired calculation abilities. Seventy-six patients with focal hemispheric lesions and 26 normal controls with demonstrated ability to read and write numbers were given a written calculation task, the Token Test, the Crosses Test, a test of Constructional Apraxia and Ravens Progressive Matrices. In the calculation task, a quantitative score represented the number of digits that were correct numerically and put in correct position. A qualitative score with emphasis on visuospatial factors was obtained by scoring each problem with the criteria used in Bentons Visual Retention Test. Analysis of the results showed that both left and right hemisphere-damaged patients performed significantly worse than controls and that patients with left posterior lesions were particularly impaired even after correction of the acalculia scores by the results of the other neuropsychological tests. These results suggest that even though different factors may contribute to calculation disorders (impairment of intelligence, visuoconstructive difficulties and above all aphasia), left posterior lesions are particularly prone to produce an impairment in calculating abilities which is partially independent from the above disorders.

Normal Rates of Forgetting of Verbal and Non-Verbal Material in Alzheimer's Disease

Recent work has suggested that patients with damage to temporal lobe structures, such as patients with Alzheimers Disease (AD), lose information from memory at an abnormally rapid rate. In contrast, data from other studies suggest that the rate of forgetting in AD is normal. In the present study, 62 patients with mild to moderate AD and 64 elderly controls were tested for their immediate and delayed recall of a short verbal passage and a modified Rey complex figure. The results suggest that although AD patients recalled less than controls, they did not forget at a faster rate during the 30 minute retention interval, supporting the finding that these memory impaired patients do not have an abnormal rate of forgetting. The data also suggest that poor initial encoding of the stimuli may be the cause of the AD patients impaired recall.

Processing Emotional Information in Alzheimer's Disease: Effects on Memory Performance and Neurophysiological Correlates

Background: There is some impairment of the ability of patients with Alzheimer’s disease (AD) to perceive emotions, but this ability seems relatively preserved compared to the impairment of other cognitive domains. Few studies have focused on the link between emotional processing and other cognitive functions, such as memory or attention. Objective: This study was designed to investigate whether the emotional content of a text can influence memory in patients affected by AD and whether this effect is related to attentional processes as measured by event-related potentials (ERP). Methods: All subjects were administered neuropsychological tests and a logical memory test including emotional and nonemotional material. ERP were recorded during an attention task. Results: AD patients had better immediate recall of sad and, to a lesser extent, happy stories than of neutral stories. This difference also affected multiple choice recognition and identification (immediate and delayed) of emotional content. The amplitude of both P300 and mismatch negativity was significantly decreased in the group as a whole. There was no correlation between P300 parameters and performance on the memory tasks, whatever their emotional content. Conclusions: The results show relatively preserved emotional processing in patients with AD and suggest that the emotional content of a context can influence memory performance. We found no evidence that this effect is mediated by attention as measured by ERP.

Acalculia: Historical development and current significance

Acalculia is a loss of calculating abilities occurring as a result of cerebral damage. This paper reviews the development of the notion of acalculia from an expected concomitant of aphasia or dementia to that of a sometimes autonomous disorder. Current evidence indicates that acalculia tends to occur particularly in lesions of the left posterior hemispheric areas.

The progressive breakdown of number processing and calculation ability: a case study.

We examined a retired Army General with Progressive Dementia whose initial major presenting complaint was dyscalculia. Our examinations revealed an orderly dissolution of calculation ability with differing dissociations in calculation ability apparent at progressive stages of cognitive decline. For example, we found that number reading and writing errors were qualitatively different from calculation errors. Numerosity knowledge and magnitude comparisons can remain intact even when other arithmetic knowledge and calculation abilities were grossly impaired. His decline in calculation abilities was first demonstrated on more complex problems (e.g., multiplication) and only in later stages on simpler (e.g., addition) problems. The patient was aware that aspects of his performance were impaired, but he was unable to state why--a dissociation between declarative and procedural knowledge.

Visuoperceptual and visuomotor abilities and locus of lesion

Possible differential effects of laterality and caudality of cerebral lesions on simple visuoperceptual and visuomotor skills were examined. As expected, the right hemisphere lesion group was significantly more impaired than the left hemisphere lesion group. The effects of the caudality of lesion, however, yielded interesting results. While the right posterior group was worse than the right anterior lesion group, as expected, the left posterior lesion group was better than the left anterior lesion group. Our findings points to a possibility that the left hemisphere, especially the anterior region, might not be as silent in processing simple visual stimuli as has been accepted.

Development of a Short Form of the Severe Impairment Battery

OBJECTIVEnThe authors sought to develop a short form of the Severe Impairment Battery (SIB).nnnMETHODSnAuthors describe the development of an empirically-derived short form of the SIB (SIB-S) by use of data from 191 subjects with severe dementia in the United States and France.nnnRESULTSnMean (standard deviation) Mini-Mental State Exam scores for the American and French samples were 7.7 (4.8) and 5.7 (3.4), respectively, and original SIB scores were 71.87 (18.34) and 58.38 (26.86), respectively. Exploratory factor analyses were conducted separately and in combination for the two samples, to determine the number of clinically meaningful factors. An eight-factor model, explaining 60.2% of the common variance, was selected. The eight constructs were described as: expressive language, memory (verbal and nonverbal), social interaction, color-naming, praxis, reading and writing, fluency, and attention. Derived SIB-S scores were 38.41 (9.12) and 29.79 (13.17) for the American and French samples, respectively.nnnCONCLUSIONSnThe original SIB is a valid and reliable research tool developed to enable reliable assessment of patients with severe dementia; it takes approximately 30 minutes to administer. The SIB-S takes only 10-15 minutes to administer, making it more appropriate for use in patients with very severe dementia, while it maintains the attributes of the original SIB.