Search

The approach of executive functions began with the early description of behavioural disorders induced by frontal damage. The development of neuropsychology has led to the description of a large variety of cognitive disorders. The interpretation in cognitive terms of these disorders has emphasized the critical impairment of executive functions which are involved in non-routine situations. The role of working memory, initially suggested by animal studies, has also largely influenced theoretical approaches. Numerous studies have been interpreted within the theoretical frameworks developed by Shallice and by Baddeley. A large amount of studies have allowed the specification of control processes (initiation, inhibition...). Recent studies are beginning to investigate cognitive disorders underlying behavioural changes such as deficits of emotional, social and metacognitive processes. In addition these studies seriously question the assumption of a unique central control system. These studies have deeply influenced the clinical approach, the assessment and the diagnosis of executive syndrome. For clinical practice, these data lead to favour specific assessment of some key behavioural and cognitive deficits based on a battery of tests and structured interview of an informant.

Introduction: Executive dysfunction is regularly reported in patients with Alzheimer's disease. Nevertheless few studies have focused on planning ability in this neurodegenerative disease., Objectives: This study aimed to investigate the formulation and the execution of plans in Alzheimer's disease using an ecological planning subtask derived from the Behavioural Assessment of the Dysexecutive Syndrome test battery, the "Zoo Map Test". There are two trials. The first trial consists of a "high demand" version of the subtask in which the subjects must plan in advance the order in which they will visit designated locations in a zoo (formulation level). In the second, or "low demand" version, the subject is simply required to follow a concrete externally imposed strategy to reach the locations to visit (execution level). The test was given to 16 patients with Alzheimer's disease and 13 normal elderly subjects., Results: The two way ANOVAs mainly showed more difficulties in patients with Alzheimer's disease than in healthy elderly in both conditions. The difference between formulation and execution was greater in patients with Alzheimer's disease than in healthy elderly. Planning impairments mainly correlated with behavioural changes (in particular motivational changes) observed by patient's relatives., Conclusion: These results suggest that patients with Alzheimer's disease have some problems to mentally develop logical strategies and to execute complex predetermined plans, which are partially related to behavioural changes.

According to Norman and Shallice, the basal ganglia are involved in the activation and maintenance of overlearned or routine scripts in action planning. This study aimed to investigate how patients with Huntington disease manipulate scripts. Ten patients with Huntington's disease and 12 normal control subjects matched by age and education were asked to re-establish the sequential order of series of script actions which were given with or without distractor elements (i.e. with or without actions belonging to trivial scripts). Compared with normal controls, patients with Huntington disease made significantly more errors in script sequencing. However there was no significant difference in performance between patients with Huntington disease and normal control subjects in inhibiting irrelevant actions. These results suggest that early Huntington's disease patients exhibit early impairment in their ability to produce temporally coherent sequences without deficit in their ability to eliminate distractors in the action domain. These results support in part the predictions of Norman and Shallice's model. From a neuroanatomical point of view, this dissociation of performance fits with what is known about the neuropathological progression of Huntington's disease in which neuronal loss progresses in a dorsal-to-ventral direction and with what was shown in patients with circumscribed frontal lobe damage. In these patients, impairment in script sequencing is related to lesions in the lateral prefrontal regions.

Grasping is associated with frontal lobe pathology. Nevertheless, there is lack of precise anatomical correlations and very few studies are published. The aim of the study was to determine the incidence of the grasping and its relationship to cerebral lesions. We studied 236 patients admitted to the Neurology Department (108 women and 128 men; mean age 65.3), and tested with a standardized procedure (De Renzi and Barbieri, 1992). A score of grasping was determined for each patient. The locations of the cerebral lesions were assessed by two neurologists using the method of Damasio and Damasio (1989). Grasping was found in 38 patients (16.1p.100) with dementia or cerebral damage. In all cases, the lesion affected the frontal lobe. The patients with grasping showed a significant higher number of lesioned areas particularly for the frontal and the parietal regions. The score of right grasping was significantly higher with a lesion in the right paraventricular frontal and in the left parietal paraventricular areas. The score of left grasping was significantly higher with a lesion in the left frontal paraventricular area. These results are discussed in relationship with motor control.

We report the case of a 56-year-old woman who died after a 2.5 years progressive course of behavioral disorders associating severe obsessive-compulsive counting with disinhibition. Neuropathological examination showed severe gliosis of the caudate nuclei whereas the lentiform nuclei and frontal cortex were not involved. In contrast with previous reports, this case lacked psychic akinesia which is usually combined with obsessive-compulsive behavior. It is a further illustration of how subcortical lesions can produce a frontal like syndrome. It suggests a fundamental role of the caudate nuclei in the control of behavior.

Reports of frequency and interpretation of intellectual and mood disorders differ in multiple sclerosis (MS). Forty-one patients with MS defined according to MacAlpine's criteria were evaluated by psychometric tests (WAIS) and neuropsychologic examinations (study of language, gnosic and praxic activities, dynamic gestural organization, memory and learning) together with, in 24 of them, the AMDP psychopathologic rating scale. Intellectual disorders were noted in 65 p. 100 of patients. Although more frequent in severe and chronic forms they were nevertheless of early onset since more than a half of the patients with onset of disease less than 5 years ago were affected. Their semiology was fairly homogeneous, combining disturbances of dynamic gestural organization (decomposition or simplification) and memory and learning deficiencies without anomalies of instrumental functions or usual psychometric mental deterioration. Application of the AMDP scale failed to reveal any psychotic type of disorders. Mood disturbances were predominant, affecting 60 p. 100 of the subpopulation studied (24 cases) and combining, in an unexpected manner: dysphoria, euphoria and depression. Only euphoria appeared to be correlated with intellectual disorders. Frequency of both intellectual and mood disorders was similar to that reported in other series published. The relative homogeneity of semiology, seen by the correlation between the different disturbances (decomposition and simplification, plateau learning curve and euphoria) and the unusual grouping of these effects, is suggestive of their organic basis. In addition, signs and symptoms resemble the neuropsychological expression of frontal lobe lesions and certain lesions of central grey nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

A case of herpes simplex encephalitis (HSE) is reported. The patient experienced short term memory disorders and irritability progressing over 3 months, without seizures or fever. The CSF was normal. CT showed a small low density area in the right posterior orbito-frontal region. At post-mortem examination, one month later, the temporal cortex appeared largely spared by necrosis, which involved the posterior orbito-frontal areas. Cowdry type A inclusions, herpes virus like particles and fluorescent reaction with HSV1 monoclonal antibodies strongly supported the diagnostic. Such atypical cases of long duration have apparently seldom been reported. They suggest that HSE should be considered in the differential diagnosis of a subacute encephalopathy.