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PubMed2004

Depressive symptoms account for deficient information processing speed but not for impaired working memory in early phase multiple sclerosis (MS).

Depressive symptoms may influence neuropsychological functioning negatively. A substantial proportion of multiple sclerosis (MS) patients exhibit neuropsychological impairments and depressive symptomatology is more common in MS as compared to healthy controls and to other neurological diseases. The objectives of the present study were to assess information processing speed, working memory and executive functions in early phase MS and to investigate whether severity of depressive symptoms account for these aspects of cognition in MS. The patients show slowed information processing speed and impaired working memory, whereas executive functioning, as measured with the Wisconsin Card Sorting Test, is unaffected. Depressive symptoms account for slowed information processing speed, but not for impaired working memory.

Adult↗

PubMed2006

[Construct validity of some episodic memory tests for psychogeriatric patients].

Episodic memory is the conscious recollection of personal experiences. In clinical practice several episodic memory tests are used, but their validity as measures of an episodic memory construct is not clear. The sensitivity and specificity of variables hypothesized to represent a distinct psychological construct is established by a pattern of convergent and discriminant validity. Confirmatory factor analysis was used to analyse the correlations between four episodic memory tests: a standardized orientation questionnaire, free recall, and two delayed recognition memory tests. The episodic memory construct was contrasted with an executive functioning construct, measured by three variables: two tasks of semantic word fluency and the Expanded Mental Control Test. The measures were taken from 813 consecutive visitors of a psychogeriatric day care centre. As a set the four indicators of episodic memory provided reliable measurement of the construct. The same was true for the three measures of the executive functioning construct. However, the strong correlation (0.89) between the two constructs implies a lack of discriminant validity and suggests that processes of executive control contribute to the successful performance on episodic memory tasks.

Aged↗

PubMed2006

Cognitive functions in juvenile and adult patients with gelastic epilepsy due to hypothalamic hamartoma.

PURPOSE: To describe extend and severity of cognitive deficits in juvenile and adult patients with gelastic seizures and hypothalamic hamartoma (HH) and to analyze the impact of epilepsy-related variables on cognitive performance. METHODS: Thirteen juvenile and adult patients (mean age, 25 years; seven men) underwent comprehensive neuropsychological testing assessing intellectual performance, attention and executive functions, verbal and visual memory, and visuospatial abilities. RESULTS: Intellectual abilities ranged from moderate mental retardation to good average performance; 54% of the patients displayed below-average global intellectual abilities. Attentional and executive functions were impaired in 23% to 46% of the patients. Below-average visuospatial capabilities were observed in 39% of the cases. Memory functions were impaired regarding both visual (77%) and verbal learning (62%). Nonparametric correlation analysis revealed a significant relation between monthly partial seizure frequency and reduced cognitive flexibility and reduced performance in mental rotation. In addition, HH volume was significantly negatively correlated with cognitive flexibility, whereas age at onset and duration of epilepsy did not show significant correlation to cognitive performance. CONCLUSIONS: More than half of the adult patients with gelastic seizures and HH displayed deficits in a broad range of cognitive functions, expressed mostly in visual and verbal learning and memory. Some of the deficits could be shown to correlate with disease-related characteristics representing the severity of the epilepsy or the size of the underlying lesion. These findings prompt for a longitudinal investigation of the development of these cognitive deficits to analyze further the relevant factors contributing to this wide spectrum of cognitive impairments.

Adolescent↗

PubMed2003

Co-ordination within and between verbal and visuospatial working memory: network modulation and anterior frontal recruitment.

Attention switching between items being stored and manipulated in working memory (WM) is proposed to be an elementary executive function. Experiment 1 reveals a similar attentional limitation within and between verbal and visuospatial WM and identifies a supramodal switching process required for switching between WM items. By using functional magnetic resonance imaging, Experiment 2 investigated brain activation correlates of parametrically varied attention switching within and between these two WM modalities. Attention switching activation was broadly distributed, was quite similar across the three conditions, and, in almost all areas, increased with increasing switching demand, indicating that attention switching recruits and modulates the entire WM network. Dorsolateral prefrontal cortex was implicated in both within- and between-modality attention switching, but no significant activation was found in ventrolateral areas, supporting dorsal-ventral process models of prefrontal organization. A functional dissociation between anterior frontal and dorsolateral prefrontal cortex was found with the former being more activated when switching attention between modalities was required. The data challenge the notion of an anatomically separate attention switching executive function, but suggest that anterior frontal areas are recruited for the additional demand of coordinating the verbal and visuospatial WM slave systems.

Adolescent↗

PubMed2000

Patterns of cognitive ageing.

Neuroanatomical evidence suggests that normal ageing affects some brain areas, and the "local" functions they support, earlier and more severely than others. Changes appear to be especially marked in the hippocampus, temporal association and prefrontal cortex. Evidence from classical neuropsychological studies suggests that these brain areas are associated with memory and "executive" functions, respectively. We may, therefore, expect that tests purported to measure these functions may be disproportionately affected in old age and that there may be evidence for some separation of these functions even within neurologically normal populations. What we also know, however, is that measures reflecting general fluid ability also decline with increasing age, so any hypothesis relating to specific "local" deficits must acknowledge and account for any "globar" changes in performance. Volunteers (n = 162) aged between 60-80 years who had completed the Cattell and Cattell Culture Fair Intelligence Test (CCF) completed the Cambridge Automated Neuropsychological Test Battery (CANTAB). The CANTAB has been administered to several patient populations and tests from the battery have been shown to be sensitive to damage in both temporal and prefrontal areas (Owen et al., 1996). Results from the test battery showed that both the Paired Associate Learning and Spatial Recognition tests were the most sensitive to normal ageing even when CCF is accounted for. In contrast, this performance on the "executive" tests, shown to be sensitive to frontal lobe damage was not related to age, and CCF scores predicted performance on these tests. These results are discussed in relation to theories of cognitive ageing and patterns of change and in relation to several important methodological and theoretical considerations for the study of executive function.

Aged↗

PubMed2001

Dysexecutive symptoms among a non-clinical sample: a study with the use of the Dysexecutive Questionnaire.

Clinical studies indicate that damage to the frontal lobes may lead to a set of symptoms collectively known as 'Dysexecutive syndrome', which is characterized by changes in emotion, personality, motivation, behaviour and cognitive aspects. Factor analytical study using questionnaires measuring dysexecutive problems in everyday life also suggests a fractionation of the dysexecutive syndrome among patients with neurological disorders. As yet, very little research has been conducted to explore the base-rate of executive problems in everyday life among the non-clinical population. This pilot study aimed to explore dysexecutive behaviour similar to that of dysexecutive syndrome reported by a non-clinical sample. A total of 93 presumably normal participants were recruited. The Dysexecutive Questionnaire and a set of clinical tests of executive function were administered to all the participants. A 5-factor solution very similar to that of a previous study was derived: inhibition (factor 1), intentionality (factor 2), knowing-doing dissociation (factor 3), in-resistance (factor 4), and social regulation (factor 5). Correlation was established among the derived factors and tests of executive function. This study provides empirical evidence that a non-clinical sample may encounter similar dysexecutive behaviours in daily life. The issue of the fractionation of the executive system among the non-clinical sample will also be discussed.

Adult↗

PubMed2001

Dysexecutive symptoms among a non-clinical sample: A study with the use of the Dysexecutive Questionnaire.

Journal Article↗

PubMed2001

Profile of cognitive functioning in women with the fragile X mutation.

Two studies tested the specificity of the neurocognitive profile of women with fragile X syndrome (FXS). First, women with an FXS full mutation were compared with women with a premutation and women without FXS who grew up in FXS families. Women with FXS had a significantly lower IQ than the other groups, and analyses of subtest profiles showed they had a relative weakness on Arithmetic and strength on Picture Completion. Women with FXS performed worse than the other groups on executive function, spatial ability, and visual memory. Next, women with FXS were compared with women without FXS matched on age and IQ. A similar IQ profile was found, but women with FXS were worse than controls only on executive function. The authors also examined which neurocognitive indices were related to the underlying biology of the disorder. Overall, the results indicated that executive rather than visuospatial deficits were primary in the neurocognitive profile of FXS.

Adolescent↗

PubMed2006

Cognitive deficits and levels of IQ in adolescent onset schizophrenia and other psychotic disorders.

Cognitive deficits have been found to be prevalent in early onset schizophrenia. Whether these deficits also characterise other early onset psychotic disorders to a similar degree is unclear, as very few comparative studies have been done. The primary purpose of this study was to compare the profile and severity of cognitive impairments in first-episode early onset psychotic patients who received the schizophrenia diagnosis to those diagnosed with other non-organic, non-affective psychotic disorders. The secondary purpose was to examine whether the profile of cognitive deficits, in terms of intelligence, executive functions, memory, attention and processing speed was global or specific. First-episode psychotic adolescents (N = 39) between the ages 11 and 17 years were included, 18 of whom were diagnosed with schizophrenia, and 21 with other non-organic, non-affective psychoses, using ICD-10 criteria. A healthy control group (N = 40) was included, matched on gender and age. Cognitive functions were assessed using WISC-III/R, the CANTAB battery, WCST, Trail Making B, fluency tasks, and Buschke's selective reminding task. A similar profile and level of impairment was found on measures of attention, executive functions, reaction time, and memory in the schizophrenic and psychotic adolescent groups. However, analyses of WISC-III factor profiles suggested that early onset schizophrenia patients may have more global IQ deficits than non-organic, non-affective psychoses when examined recently after illness onset. Compared to the deficits of adult schizophrenia described in the literature, the results suggest relatively spared simple reaction times in early onset patients.

Adolescent↗

PubMed2001

Practice effects on the Wisconsin Card Sorting Test-64 Card version across 12 months.

The Wisconsin Card Sorting Test (WCST: Heaton, Chelune, Talley, Kay, & Curtiss, 1993) is among the most commonly administered measures of executive function. Recently, a short form of the test was developed (WCST-64: Kongs, Thompson, Iverson, & Heaton, 2000), and it affords psychometric properties commensurate with the full version of the test. Yet, similar to other measures of executive function, relatively little is known concerning the effects of repeated administration on the WCST-64. Towards this end, 53 men (age M = 32.38) were administered the WCST-64 twice over 12 months, and scores on several indices improved significantly during this interval. Suggestions concerning the use of these measures in longitudinal research designs and clinical follow-up examinations are offered, and reliable change indices concerning these measures are included.

Adult↗

PubMed2006

Deviant strategy on The Modified Six Elements Test in patients with schizophrenia.

Impaired executive functioning is found in a considerable proportion of schizophrenia patients. Neuropsychological tests are originally designed to measure the behavior of neurological patients and may therefore miss psychiatry-related cognitive deficits. Qualitative information on tests for executive functioning is important in psychiatric populations. The Modified Six Elements Test (MSET) is a planning test that consists of 6 tasks, for which subjects have limited time and have to obey to switching rules. This study concerns a qualitatively different approach schizophrenia patients use on the MSET, and its relationship with cognitive measures. MSET scores and strategies of schizophrenia patients were compared to those of healthy controls, closed-head-injury patients, and peripheral injury patients. Also, schizophrenia patients and healthy controls were compared on verbal memory and vigilance. Schizophrenia patients finish fewer assignments on the MSET, receive a lower profile score compared to healthy controls, and use a different strategy on the test compared to the other groups. They also perform below healthy controls on the tests for verbal memory and vigilance. Use of the different strategy in schizophrenia patients was related to impaired cognitive functioning. An interesting strategy used by schizophrenia patients on the MSET appears to be indicative of impaired cognitive functioning. This strategy may be a compensatory strategy to spare cognitive resources. It could also be the result of a concrete interpretation of the test instructions.

Adolescent↗

PubMed2006

Cognitive profile in CADASIL.

BACKGROUND: The spectrum of cognitive alterations associated with CADASIL, a model of pure vascular dementia, has not been thoroughly evaluated. OBJECTIVES: The aims of this study were: (i) to describe the cognitive profile in CADASIL patients according to age; (ii) to compare the profile of patients with dementia with that of patients without dementia; and (iii) to determine the association between alterations in performance in different cognitive domains. METHODS: Forty two consecutive individuals with CADASIL (35-73 years old) were investigated. Cognitive skills were analysed in five domains (executive functions, reasoning, attention, memory, visuospatial abilities) according to age and compared between patients with and without dementia. Associations between cognitive performance and stroke were tested. RESULTS: The youngest patients presented with attention (69%), memory (70%), and executive disturbances (100%). Visuospatial abilities and reasoning deteriorated with age, mainly after the age of 60. About one quarter of patients had dementia, and 75% of these were >60 years of age. Age >60 years was associated with a Rankin score >3 and a significant deficit in all cognitive domains. No association was found between dementia and the number of ischaemic attacks. Episodic memory disorder was characterised by difficulties in retrieval rather than impairment of the encoding process. CONCLUSION: Cognitive decline in CADASIL is dominated by early impairment of executive functions. Skills in other cognitive domains deteriorate with age and are found to be diffusely impaired in patients with dementia. The relative preservation of the encoding process in episodic memory impairment, even in individuals with dementia, is noteworthy.

Adult↗

PubMed1999

Repeatable battery for the assessment of neuropsychological status as a screening test in schizophrenia, II: convergent/discriminant validity and diagnostic group comparisons.

OBJECTIVE: In a companion article in this issue of the Journal, the authors presented data suggesting that the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is sensitive to the types of impairments observed in schizophrenia, correlates highly with standard measures of intelligence and memory, and is related to employment status in a group of patients with schizophrenia drawn from a tertiary care research center. The objectives of the current study were 1) to determine if evidence of the convergent validity of the RBANS could be replicated in a diagnostically heterogeneous sample drawn from a public mental health system, 2) to examine the relationship of the RBANS to a broad neuropsychological battery, and 3) to compare the performance of patients with schizophrenia and patients with bipolar disorder on a neuropsychological battery and the RBANS. METHOD: The RBANS and a standard neuropsychological battery, including the WAIS-III and Wechsler Memory Scale, 3rd ed. (WMS-III), were given to 150 patients drawn from a larger study of vocational rehabilitation. RESULTS: Correlations of RBANS total scores with WAIS-III and WMS-III variables were highly similar across study groups. The RBANS correlated highly with a composite z score derived from 22 standard measures of IQ, memory, language, motor, attention, and executive function. Principal component analyses of the neuropsychological battery resulted in a six-factor solution: the RBANS correlated most highly with a general ability factor and had limited correlations with measures of motor performance, vigilance, and executive function. Patients with schizophrenia demonstrated greater deficits on the neuropsychological battery and the RBANS than patients with bipolar disorder. CONCLUSIONS: These data suggest that the RBANS is a useful screening instrument for assessing the severity of cognitive impairment in psychiatric populations.

Adult↗

PubMed2004

A neuropsychological comparison of psychotic disorder following traumatic brain injury, traumatic brain injury without psychotic disorder, and schizophrenia.

Neuropsychological functioning in individuals with psychotic disorder following traumatic brain injury (PDFTBI), traumatic brain injury without psychosis (TBIWP), and schizophrenia were compared against each other and to the means of normal subjects. It was predicted that the PDFTBI group would be similar to the schizophrenic group in patterns of deficits, but milder in severity. Compared to scores from a normal sample, the PDFTBI group scored significantly lower in intelligence, vocabulary, verbal memory, and executive functioning, while the schizophrenic group scored significantly lower in intelligence, working memory, verbal memory, visual spatial abilities, and executive functioning. No differences were found between normal subjects and the TBIWP group. Implications of our findings for the conceptualization of psychotic disorders are discussed.

Adult↗

PubMed2006

The presence of background dopamine signal converts long-term synaptic depression to potentiation in rat prefrontal cortex.

Executive functions of the brain are believed to require tonic dopamine inputs to the prefrontal cortex (PFC). It is unclear, however, how this background dopamine activity controls synaptic plasticity in the PFC, a possible underlying mechanism of executive functions. Using PFC slices, we show that pairing of dopamine with weak tetanic stimulation, a maneuver that otherwise induces NMDA receptor-independent long-term depression (LTD), induces long-term potentiation (LTP) when "primed" with dopamine. This "priming" occurs through the combined activation of D1 and D2 receptors and requires 12-40 min to develop. Moreover, concurrent synaptic activation of NMDA receptors during priming is necessary for this novel form of LTP. We suggest that a role of background dopamine signals in the PFC is to prevent high-frequency synaptic inputs from abnormally inducing LTD and to secure the induction of LTP.

Animals↗

PubMed1996

The cerebellum and cognitive function: implications for rehabilitation.

OBJECTIVE: To characterize the cognitive effects of isolated cerebellar lesions. DESIGN: Review of two inpatient cases. SETTING: The rehabilitation unit of a tertiary general hospital. PATIENTS OR OTHER PARTICIPANTS: Two patients with acute ischemic strokes who had solitary cerebellar infarcts. INTERVENTIONS: Assessment with standard neuropsychological tests. Scores were compared with patients' premorbid levels and standardized test norms. A classical conditioning eyeblink paradigm was performed. MAIN OUTCOME MEASURES: Neuropsychological measures of intellectual and executive functions, learning and memory, visual-spatial abilities, language functioning, fine motor speed, and dexterity. RESULTS: Test findings suggested lesion-associated deficits in higher aspects of cognition (visuospatial reasoning, verbal and visual memory, and intellectual and executive functions). These functions are not usually associated with the fundamentally motoric role of the cerebellum. CONCLUSIONS: (1) Lesions in the cerebellum can be associated with impairments in higher cognitive functioning. (2) Such effects may be severe enough for a diagnosis of dementia under current diagnostic criteria. (3) These rehabilitation patients may benefit from comprehensive cognitive examination to determine if cognitive effects will detract from their participation. (4) Further research is needed to localize which cerebellar areas affect which cognitive abilities.

Aged↗

PubMed2006

The role of the striatum in processing language rules: evidence from word perception in Huntington's disease.

On the assumption that linguistic faculties reflect both lexical storage in the temporal cortex and combinatorial rules in the striatal circuits, several authors have shown that striatal-damaged patients are impaired with conjugation rules while retaining lexical knowledge of irregular verbs [Teichmann, M., Dupoux, E., Kouider, S., Brugières, P., Boissé, M. F., Baudic, S., Cesaro, P., Peschanski, M., & Bachoud-Lévi, A. C. (2005). The role of the striatum in rule application. The model of Huntington's disease at early stage. Brain, 128, 1155-1167; Ullman, M. T., Corkin, S., Coppola, M., Hickok, G., Growdon, J. H., Koroshetz, W. J., & Pinker, S. (1997). A neural dissociation within language: Evidence that the mental dictionary is part of declarative memory, and that grammatical rules are processed by the procedural system. Journal of Cognitive Neuroscience, 9, 266-276]. Yet, such impairment was documented only with explicit conjugation tasks in the production domain. Little is known about whether it generalizes to other language modalities such as perception and whether it refers to implicit language processing or rather to intentional rule operations through executive functions. We investigated these issues by assessing perceptive processing of conjugated verb forms in a model of striatal dysfunction, namely, in Huntington's Disease (HD) at early stages. Rule application and lexical processes were evaluated in an explicit task (acceptability judgments on verb and nonword forms) and in an implicit task (lexical decision on frequency-manipulated verb forms). HD patients were also assessed in executive functions, and striatal atrophy was evaluated with magnetic resonance imaging (bicaudate ratio). Results from both tasks showed that HD patients were selectively impaired for rule application but lexical abilities were spared. Bicaudate ratios correlated with rule scores on both tasks, whereas executive parameters only correlated with scores on the explicit task. We argue that the striatum has a core function in linguistic rule application generalizing to perceptive aspects of morphological operations and pertaining to implicit language processes. In addition, we suggest that the striatum may enclose computational circuits that underpin explicit manipulation of regularities.

Adult↗

PubMed1995

Neuropsychological and neuroanatomical correlates of confabulation.

In the present exploratory investigation we report nine confabulatory patients of comparable age, education, and general level of intelligence in the acute epoch of recovery after rupture and clipping of ACoA aneurysms. Five of the nine cases had "spontaneous" confabulation, severe anterograde amnesia, markedly poor attentional and executive functions, and denial of illness. These patients all had multiple lesions that involved basal forebrain, ventral frontal lobe, and striatum. The other four patients manifested only "momentary" or "provoked" confabulations. These patients also had severe anterograde amnesia but showed relatively mild deficits in executive functions. These patients had lesions restricted to the basal forebrain except for one who had additional orbital frontal damage. Analysis of these two groups of confabulatory patients suggests that there is a common profile of deficits and anatomic foundation associated with confabulation; "spontaneous" confabulation appears to require extensive, simultaneous disruption of medial basal forebrain and frontal cognitive systems resulting in profound executive and memory deficits, whereas more limited lesions to the basal forebrain or orbital frontal cortex will result in "transient" or "provoked" confabulatory responses and a more restricted profile of cognitive deficits.

Adult↗