Guy Darcourt

Clustering and switching strategies in verbal fluency tasks: Comparison between schizophrenics and healthy adults

Verbal fluency tasks are frequently used in clinical neuropsychology. Clustering (the production of words within semantic subcategories) and switching (the ability to shift between clusters) have been described as 2 components underlying fluency performance. We compared the use of clustering and switching in schizophrenic patients and healthy subjects. Seventy-eight schizophrenic subjects (DSM-IV criteria) and 64 control participants matched for age and educational level were recruited. Negative, disorganized, and productive clinical dimensions were evaluated using the SANS and SAPS scales. The number of words generated per semantic-phonemic cluster and the number of switches were evaluated during 2 verbal fluency tasks (phonemic and semantic). In the healthy controls switching and clustering were closely related to the total number of words generated in the verbal fluency tests. The role of the 2 components was partly dependent on the specific task. Switching was prevalent in formal fluency, while both switching and clustering contributed to semantic fluency. In comparison to the healthy controls, the overall group of schizophrenic patients showed a significant impairment of switching in the formal fluency task and of both switching and clustering in the semantic fluency task, and both the negative and disorganized dimensions correlated with verbal fluency performance, the number of swtiches during the phonemic fluency task, and the clustering during semantic fluency task.

Lack of initiative and interest in Alzheimer's disease: a single photon emission computed tomography study

Apathy is defined as a lack of motivation. The aim of this study was to investigate the relation between two major dimensions of apathy (lack of initiative and lack of interest) and brain perfusion. in patients with Alzheimers disease (AD). Brain perfusion was measured by single photon emission tomography (SPECT). Thirty‐one AD patients were included. Lack of initiative and interest were assessed with the Apathy Inventory. Nineteen AD subjects presented a lack of initiative and interest pathological score whereas 12 AD subjects did not. The lack of initiative and interest score correlated significantly with the right frontal and the right inferior temporal lobes. The AD patients with lack of initiative and interest showed a significantly lower perfusion in the right anterior cingulate than the AD patients without lack of initiative and interest. These results derive from rather small subgroups of patients but have the interest to dismantle the complementary aspects of emotion and motivation in apathy and suggest that the latter one is more related to cingulate area.

Relationship between impulsivity and platelet serotonin content in adolescents

The relationship between impulsivity and serotonin function was explored in impulsive and non-depressed adolescents. Platelet serotonin content was chosen as a peripheral indicator of central serotonin function. Impulsivity was assessed with a questionnaire. All measures were performed once a week over a 6-week period for all subjects. Subjects comprised eight adolescent inpatients who were hospitalized as a result of their impulsive acts and eight healthy age- and sex-matched control subjects. Mean platelet serotonin concentration was significantly higher in the impulsive group than in the control group. Platelet serotonin concentration was positively correlated with the intensity of impulsivity in the patient group.

Verbal fluency in schizophrenia: The role of semantic clustering in category instance generation

The aim of this study was to determine whether schizophrenic patients impairment in semantic verbal fluency tasks is due to difficulties in organizing their search or, in other words, in organizing output in terms of clusters of meaningfully related words. Consecutive association of words belonging to subcategories of the semantic task was defined as semantic clustering. A categorical verbal fluency task was first administered to 100 healthy subjects and then to 22 schizophrenic patients and 22 healthy subjects matched for sex, age and education. In the normal population, semantic clustering was found to be involved in word generation. A large number of semantic clusters indicated efficient organization of semantic knowledge and led to better word production. Schizophrenic patients showed impaired verbal fluency and generated a smaller number of semantic clusters than the control subjects. These findings point to a defect in self-initiation of semantic categorization in schizophrenia.

Evaluation of the supervisory system in elderly subjects with and without disinhibition

UNLABELLEDnDisinhibition and irritability, defined as loss of behavioral and emotional control, are frequent in the elderly. The working hypothesis for this study was that these disorders are associated with a cognitive alteration of control processes that manifests as non-routine behavior because of the dysfunction of a general executive component known as the supervisory attentional system (SAS).nnnMETHODSnA total of 28 elderly subjects with mild cognitive impairment were recruited and divided into two groups using the Neuropsychiatric Inventory. Fourteen subjects were allocated to the disinhibited group and 14 subjects matched for age, sex and educational level formed a disinhibition-free control group. The neuropsychological battery included the following tests: Mini Mental Score Evaluation, Boston Naming test, Token test, Trail Making and Verbal Fluency. Two tasks were specifically designed to stress the SAS: 1) A specific verbal sentence arrangement task in which subjects had to use sequential reasoning with verbal material. Each test sequence consisted of a series of words shown in jumbled order. The construction of some sequences had to be done by using familiar routine associations (valid conditions). In contrast, other sequences required the overriding selection of familiar routine associations, which were inappropriate within the general context of the task (invalid conditions). 2) Using the Continuous Performance Test, four aspects were evaluated: sustained, selective, preparation and suppressive attention.nnnRESULTSnThe only group differences in neuropsychological test results were the following: 1) the sentence arrangement task. In comparison with the control group, the disinhibited group was impaired in invalid conditions and the calculated difference between the number of correct responses in invalid conditions minus that in valid conditions was significantly higher; and 2) the CPT. Disinhibited subjects had a significantly lower number of hits, exclusively in the suppressive attention paradigm. These results suggest that subjects with disinhibition have impaired supervisory system function.

Faut-il traiter les troubles de la personnalité ?

Personality disorders are mental diseases in their own right. Their common characteristic is their onset during adolescence or, at the latest, in early adulthood. Personality disorders are very diverse and range from neuroses to psychoses. Personality disorders spontaneously become chronic, but they are nonetheless accessible to treatment. Possible treatments include psychoanalytic and cognitive-behavioral psychotherapies and psychotropic medications.

Non Cognitive Symptoms in Alzheimer’s Disease

In Alzheimer’s disease (AD), non-cognitive symptoms, are particularly important because they are associated with caregiver distress, they increase the likelihood of institutionalization and may be associated with more rapid cognitive decline (Teri et al., 1990; Mortimer et al., 1992). The term non-cognitive has been chosen to distinguish these symptoms from those that are cognitive in origin (i.e. symptoms that arise directly from impairments in memory, language or visuospatial function). However, the distinction is not always clear (Rabins, 1994). In fact, blurred delimitation of the field is a central problem for investigation. As mentioned by Gilley (1993) in his review, previous studies have included behavioral manifestations of cognitive dysfunction, vegetative disturbances, psychiatric symptoms, personality disorders and activity of daily living. As a consequence of this variability in definitions, no single estimate can be made of the overall prevalence of disordered behavior in AD.

A single photon emission computed tomography study of cerebral regional perfusion changes induced by a learning task in subjects with mild memory impairment

Fifteen nondemented subjects with memory complaints underwent serial single photon emission computed tomography (SPECT) studies with technetium-99m-d, l-hexamethyl-propylene amine oxime (HMPAO) as tracer. Scans were carried out under a baseline conditions and during the learning phase of the Memory Efficiency Profile (MEP), a combined visual perception and memory task developed by Rey. Results indicate a positive correlation between activation, as indexed by HMPAO uptake, and neuropsychological assessment. Right temporal activation was correlated with MEP immediate recall. The right cerebellum was correlated with both MEP immediate and delayed recall. This study suggests that SPECT can show cortical activation during cognitive performance in subjects with mild memory impairment.

Serotoninergic Symptomatology in Dementia

In adults, serotonin disturbances have been implicated in general depression (see Gjerris et al., 1987). In 1970, Van Praag et al. demonstrated a decrease in serotonin turnover in patients with endogenous depression, due to a probenecid induced effect on the accumulation of its metabolite, 5-HIAA, in cerebrospinal fluid (CSF). In 1976, Asberg, observing the bimodal 5-HIAA distribution in the CSF, suggested a relationship between low 5-HIAA levels and a high incidence of suicide attempts and great aggressiveness. The lowest levels of 5-HIAA are found following violent suicide attempts (Asberg et al., 1984, Brown et al., 1982 and Brown and Goodwin, 1986). Many studies have demonstrated close correlations between low 5-HIAA CSF levels and insomnia (Banki and Arato, 1983; Hartmann and Greewald, 1984); aggressiveness (Coccaro, 1989; Kruesi et al., 1990); impulsiveness (Zuckerman, 1986; Plutchik and Van Praag; 1989); irritability (Linnoila et al., 1983; Lopez-Ibor, 1988; Van Praag et al., 1988, 1990); pain (Basbaum and Fields, 1984); alcoholism (Roy et al., 1990) and eating disorders (Brewerton et al., 1990). Animal models have identified a common dimension to these behavioral disturbances, i.e. intolerance of waiting and an inability to defer a reaction (Soubrie, 1986).

Use of SPECT in Early Diagnosis and to Monitor the Effect of Drugs in Alzheimer Disease

Basic research to date suggests that brain imaging methods, such as Positron Emission Tomography (PET) and Single Photon Emission Tomography (SPECT) will have great success as tools to aid the clinician in the diagnosis and monitoring of a patient’s clinical course. On one hand, PET techniques allow evaluation of different aspects of brain characteristics such as cerebral blood flow (CBF), metabolism or specific receptors functioning. Furthermore PET offers high sensitivity and resolution. On the other hand, the SPECT investigation field seems to be more restricted (essentially CBF); however, SPECT facilities are widely available in most hospitals since they use a much lower cost technology. Therefore, SPECT could represent an interesting tool for the clinical management of Alzheimer’s disease (AD) patients. A particularly interesting point concerns the difficulty to evaluate therapeutic interventions. Activation studies consist of inducing differences in brain metabolism through manipulations of behavior or drugs. Using this technique it is possible to investigate the pattern changes of tracer uptake during a cognitive or pharmacological stress in comparison with determined basal conditions. There are at least two main practical interests to use this kind of procedure. The first one concerns the possibility to increase the accuracy of early diagnosis of dementia. In fact, pharmacological treatments developed for AD are mostly effective in the mild stages of the disease and a well chosen specific cortical “stress test” would be better suited than baseline conditions to demonstrate patterns of regional decrease in brain activity. The second one concerns the metabolic effects of these drugs and their relationship with clinical changes.