[Investigation of set-shifting ability in patients with Parkinson's disease: influence of task sequence type]. / Evaluation de la flexibilité de patients atteints de la maladie de Parkinson dans une épreuve de permutation de tâches.

INTRODUCTION: The aim of the present study was to investigate the origin of set-shifting deficits observed in Parkinson's disease (PD). METHODS: Seventeen patients diagnosed as having idiopathic PD were compared with 15 control subjects. We used a task-switching paradigm, including two tasks (task A and task B) so that subjects were required to switch either immediately after a switch-trial (i.e. alternating switch or ABA task sequence) or following one or two non-switch trials (ABBA or ABBBA task sequences). RESULTS: In both groups, switch cost (SC) in ABA task sequence was larger than SC in ABBA task sequence (p<0.05) and SC was larger in ABBA than ABBBA task sequence (p<0.05). PD patients demonstrated an increased SC compared to controls for alternating switch trials (p<0.01). Alternatively, when required to switch to a task abandoned two or three trials earlier (i.e. ABBA and ABBBA tasks sequences), patients did not demonstrate increased SC compared to controls. DISCUSSION AND CONCLUSION: The fact that SC associated with alternating switch trials was exacerbated in PD patients may reflect difficulties for switching to a recently inhibited task-set. In conclusion, our results indicate that set-shifting deficits in PD patients may depend of the type of task sequence.

Self-consciousness and Alzheimer's disease.

OBJECTIVES: To propose a neuropsychological study of the various aspects of self-consciousness (SC) in Alzheimer's disease. METHODS: Forty-five patients with probable mild or moderate AD were included in the study. Severity of their dementia was assessed by the Mini Mental State (MMS). Fourteen questions were prepared to evaluate SC. RESULTS: No significant correlations were found between SC score and educational level, age, and duration of disease. A significant correlation was found between SC score and the severity of dementia, whereas frontal disturbances were just short of the significance threshold. The various aspects of SC were not impaired to the same degree. The most disturbed ones were awareness of cognitive deficiencies, moral judgements and prospective memory. The least disturbed aspects were awareness of identity and of mental representation of the body. Items relating to anosognosia and moral judgements were significantly correlated with the MMS score, whereas affective state, body representation disorders, prospective memory, and capacities for introspection were not related to the severity of the dementia. Consciousness of identity was sound, regardless of MMS score. CONCLUSIONS: AD clearly induces an heterogeneous impairment of SC. SC requires a convergence of many neural networks. In AD, neuronal alterations involve many cortical areas and information sent to the associative frontal cortex from memory, language and visuospatial areas is lacking or disturbed. Thus, the sequential order of successive stimuli cannot be maintained by the heteromodal associative cortex (dorsal convexity of the prefrontal cortex), and the supramodal associative cortex (located rostrally in the frontal lobes) is unable to provide reliable monitoring and assessment of simultaneous neural cognitive networks carrying insufficient and inadequate input. The core deficiency in AD patients might be impaired SC equated with the disability to maintain sequential and simultaneous "attention to life". The Self-Consciousness Questionnaire, a clinical scale providing multidimensional measurement, indicates that different aspects of consciousness are not correlated with overall cognitive deficiency as determined by the MMSE.

Neuropsychological disturbances in cerebellar infarcts.

BACKGROUND: Recent clinical and research reports suggest that the cerebellum may contribute to the modulation of higher cognitive functions. MATERIAL AND METHODS: We included 15 consecutive patients with isolated cerebellar infarcts (4 superior cerebellar artery territory infarcts, 1 anterior inferior cerebellar artery territory infarct and 10 posterior inferior cerebellar artery territory infarcts), all confirmed by magnetic resonance imaging. These subjects plus 15 controls matched for age, sex, and educational level underwent a neuropsychological test battery including vocabulary, similarities and block design subtests of the Wechsler Adult Intelligence Scale Revised (WAIS-R); verbal fluency tests (categorial, phonemic, and alternate categorial fluency tests); Rey's 15 auditory word learning list; the paced auditory serial addition task; the Stroop test and the Zerssen Rating Scale. One year after the cerebellar infarct, each subject with cerebellar infarct was asked to undergo a second neuropsychological examination with the same test battery. RESULTS: Patients with cerebellar infarcts exhibited significantly lower neuropsychological performances compared to those of the control group without any obvious difference between the different vascular cerebellar territories. After 1 year of follow-up, this neuropsychological impairment tended to improve. CONCLUSIONS: The pattern of deficits observed in isolated cerebellar infarcts highlights the nonmotor functions of the cerebellum and functional relationship between the cerebral cortex and the cerebellum.

[Amyotrophic lateral sclerosis and cognition disorders. Neuropsychological study of a population of 26 patients]. / Sclérose latérale amyotrophique et troubles cognitifs. Etude neuropsychologique d'une population de 26 patients.

Typical amyotrophic lateral sclerosis (ALS) is described as a motoneuron disease which spared cognitive functions. Recent studies reported cognitive impairement associated with classical ALS. Gallasi and al. (1985) detect subtle cognitive impairement sparing memory in a population of 22 patients affected with sporadic motoneuron disease. Iwasaki and al. (1990) finds lower scores, including memory tests. Our study evaluated 26 patients compared with 26 control subjects with neurospychological tests (rapid evaluation of cognitive function fluency, Weschler adult intelligence scale, Wisconsin cards, Rey scheme, memory tests - Luria -, trail making, visual retentional test of Benton Violon Seyll test). All the neuropsychological tests were significantly lower for the patients group. The cognitive impairement is global: memory and frontal functions were not spared and this impairement is also subtle. It may easily go undetected without tests. We cannot isolate a cortical or subcortical profile of the deterioration.