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Working memory performance in poor outcome schizophrenia: relationship to age and executive functioning.

Performance on the Letter-Number Sequencing (LNS) and Wisconsin Card Sorting Tests (WCST) have been shown to be significantly correlated in patients with schizophrenia, a relationship postulated to be due to working memory demands of the two tests (Gold, Carpenter, Randolph, Goldberg, & Weinberger, 1997). An alternative explanation for the association between these two tests is their sorting demands, in that both require sorting of information albeit in slightly different ways. If the latter explanation is valid, then working memory tasks that do not require sorting or other conceptualization demands should be less predictive of WCST performance than LNS. These hypotheses were examined in 34 poor outcome patients with schizophrenia, one-half of whom were over the age of 65. Patients were evaluated on Digit Span Forward, spatial working memory, LNS, and the WCST. It was found that WCST performance was significantly associated with performance on the LNS but no other working memory task. Age related performance differences were greatest on the WCST Categories and floor effects were noted on this test in one-half of the subjects. Analyses predicting WCST Categories in subjects whose scores were greater than zero (n = 16) also demonstrated that LNS, but not Digit Span or spatial working memory (any delay) predicted WCST performance. These findings indicate that LNS may be an index of executive functioning, particularly in patients who cannot perform the WCST.

Adult↗

Assessment of executive function in patients with mild traumatic brain injury.

BACKGROUND: The nature of functional deficit after mild traumatic brain injury (TBI) defined by Glasgow Coma Score of 13-15 is not fully described. This study explored the sensitivity of several neuropsychological tests to identify sequelae of mild traumatic brain injury (TBI). METHODS: Eleven adult patients with mild TBI admitted to a Level 1 trauma center were studied. The battery of tests included the Wechsler Intelligence Scale for Children -Revised: Mazes Subtest, Trails A and B, the Boston Naming Test, The Multilingual Aphasia Examination: Controlled Oral Word Association Test, and the Paced Auditory Serial Addition Task. RESULTS: Control subjects performed significantly better than patients with mild TBI on Trails A and B, the Controlled Oral Word Association Test, and Paced Auditory Serial Addition Task (subtests 2-4). No significant differences in performances between patients and controls was found for the Wechsler Intelligence Scale for Children -Revised: Mazes Subtest, Boston Naming Test, and Paced Auditory Serial Addition Task Subtest 1. CONCLUSION: The results suggest that tests of specific frontal lobe executive functions are valuable in diagnosing and monitoring recovery from mild TBI.

Adult↗

Memory and executive function impairment predict dementia in Parkinson's disease.

We analyzed the association of neuropsychological test impairment at baseline with the development of dementia in idiopathic Parkinson's disease (PD) patients. A cohort of nondemented PD patients from northern Manhattan, NY was followed annually with neurological and neuropsychological evaluations. The neuropsychological battery included tests of verbal and nonverbal memory, orientation, visuospatial ability, language, and abstract reasoning. The association of baseline neuropsychological tests scores with incident dementia was analyzed using Cox proportional hazards models. The analysis controlled for age, gender, education, duration of PD, and the total Unified Parkinson's Disease Rating Scale motor score at baseline. Forty-five out of 164 patients (27%) became demented during a mean follow-up of 3.7 +/- 2.3 years. Four neuropsychological test scores were significantly associated with incident dementia in the Cox model: total immediate recall (RR: 0.92, 95% CI: 0.87-0.97, P = 0.001) and delayed recall (RR: 0.73, 95% CI: 0.59-0.91, P = 0.005) of the Selective Reminding Test (SRT), letter fluency (RR: 0.87, 95% CI: 0.77-0.99, P = 0.03), and Identities and Oddities of the Mattis Dementia Rating Scale (RR: 0.85, 95% CI: 0.73-0.98, P = 0.03). When the analysis was performed excluding patients with a clinical dementia rating of 0.5 (questionable dementia) at baseline evaluation, total immediate recall and delayed recall were still predictive of dementia in PD. Our results indicate that impairment in verbal memory and executive function are associated with the development of dementia in patients with PD.

Aged↗

Rehabilitation of executive function: facilitation of effective goal management on complex tasks using periodic auditory alerts.

The 'dysexecutive syndrome' represents a major challenge to functional recovery and adaptation following brain injury--and an important target for rehabilitation. Previous reports of everyday difficulties, and performance on complex, life-like tasks, indicate that an adequately represented goal may become neglected as patients become overly engaged in current activity. Here we examine whether the provision of brief auditory stimuli, acting to interrupt current activity and to cue patients to consider their overall goal, would improve performance in a complex task. Ten brain injured patients completed a modification of Shallice and Burgess' Six Elements task under two conditions. In the 'Hotel' test, the patients were asked to try and do some of each of five sub-tasks within 15 min. As the total time to complete all of the tasks would exceed an hour, the measure emphasises patients' ability to monitor the time, switch between the tasks and keep track of their intentions. Without the external auditory cues, the patients performed significantly more poorly than age- and IQ-matched control volunteers, a common error being to continue performing one task to the detriment of beginning or allocating sufficient time to others. When exposed to the interrupting tones, however, their performance was both significantly improved and no longer significantly different from the control group on important variables. The results have value in assessment in helping to attribute poor performance to 'goal neglect' rather than, for example, poor memory or comprehension. They also suggest that providing environmental support to one aspect of executive function may facilitate monitoring and behavioural flexibility--and therefore the useful expression of other skills that may be relatively intact.

Acoustic Stimulation↗

Influence of executive function on locomotor function: divided attention increases gait variability in Alzheimer's disease.

OBJECTIVES: To evaluate how cognitive function and divided attention affect gait in Alzheimer's disease (AD). DESIGN: Cross-sectional intervention study with subjects serving as their own controls. SETTING: Inpatient unit and outpatient clinic for patients with dementia located at a Veterans Affairs Medical Center. PARTICIPANTS: Twenty-eight patients diagnosed with probable AD. INTERVENTION: Performance of a cognitive task (repeating random digits) while walking. MEASUREMENTS: Neuropsychological measures including clock drawing, verbal fluency, and digit span were obtained along with the Clinical Dementia Rating and Mini-Mental State Examination, the measures of dementia severity. Gait speed and stride-to-stride variability of gait rhythm were measured, once during normal walking and once during dual-task walking. RESULTS: During usual walking, subjects walked slowly and with greater gait variability than older adults without AD. Gait speed was significantly reduced (P<.012) and gait variability increased with dual-task walking (P<.007). The effect on gait variability was larger than the effect on gait speed (P<.015). Executive and neuropsychological function were significantly (P<.02) associated with the increased gait variability that occurred when walking with divided attention but not with gait speed or usual, single-task walking measures of gait. CONCLUSION: Divided attention markedly impairs the ability of patients with AD to regulate the stride-to-stride variations in gait timing. This susceptibility to distraction and its effect on stride time variability, a measure of gait unsteadiness, could partially explain the predilection to falling observed in patients with dementia. The results also support the concept that persons with AD have significant impairments in the cognitive domain of attention and that locomotor function relies upon cognitive, especially executive, function.

Aged↗

Executive functions and achievements in school: Shifting, updating, inhibition, and working memory.

Links have recently been established between measures of educational attainment and both verbal and visuo-spatial aspects of working memory. Relationships have also been identified between specific executive functions-shifting, updating, and inhibition-and scholastic achievement. In the present study, scholastic attainment, shifting, updating, inhibition, and verbal and visuo-spatial working memory were assessed in 11- and 12-year-old children. Exploratory factor analysis identified two executive factors: one associated with updating functions and one associated with inhibition. Updating abilities were closely linked with performance on both verbal and visuo-spatial working memory span tasks. Working memory was closely linked with attainment in English and mathematics, and inhibition was associated with achievement in English, mathematics, and science. Domain-specific associations existed between verbal working memory and attainment in English, and between visuo-spatial working memory and attainment in English, mathematics and science. Implications of the findings for the theoretical analysis of executive functioning, working memory and children's learning are discussed.

Child↗

Executive function in sleep apnea: controlling for attentional capacity in assessing executive attention.

STUDY OBJECTIVES: As the effects of general slowness and decreased attentional capacity on higher executive attention have not been fully taken into account in the sleep apnea literature, we statistically controlled for basic attentional performance in evaluating executive attention per se in sleep apnea patients. DESIGN: A case-controlled design was used with comparison of basic and executive attentional tasks. PARTICIPANTS: Thirty-six polysomnographically diagnosed patients (mean apnea-hypopnea index = 60.5 +/- SD 31.6) participated, together with 32 healthy controls. MEASUREMENTS AND RESULTS: Neuropsychological tests included Trail Making part A and B, Symbol Digit Modalities (SDMT), Digit Span forward and backward, Stroop Color-Word, Five-Point design fluency, and an Attentional Flexibility task. Patients' vigilance data indicated time-on-task decrements after 10 minutes. Moreover, their performance was significantly reduced on the SDMT (effect size d = 0.93), the Digit Span forward task (d = 0.44), the number of errors on the basic 2-choice reaction time subtest of the Attentional Flexibility task (d = 0.74) and the mean RT on the actual Attentional Flexibility subtest (d = 0.54). It has been argued that the latter poor performance was probably primarily related to the task's phonologic loop component of working memory rather than to an attentional switching deficit per se. No other performance differences were found between patients and healthy controls. CONCLUSIONS: In addition to vigilance decrements, attentional capacity deficits clearly emerge, ie, slowed information processing and decreased short-term memory span. However, no specific clinical indications for executive attentional deficits--such as disinhibition, distractibility, perseveration, attentional switching dysfunction, decreased design fluency, or an impaired central executive of working memory--are found in patients with severe sleep apnea. Their cognitive performance seems very similar to the cognitive decline found after sleep loss and qualitatively different from patients with chronic obstructive pulmonary disease, suggesting sleepiness as the primary factor in a parsimonious explanation for the attention deficits in sleep apnea, without the need to assume prefrontal brain damage.

Attention↗

Individual differences in executive functioning and theory of mind: An investigation of inhibitory control and planning ability.

This research examined the relative contributions of two aspects of executive function-inhibitory control and planning ability-to theory of mind in 49 3- and 4-year-olds. Children were given two standard theory of mind measures (Appearance-Reality and False Belief), three inhibitory control tasks (Bear/Dragon, Whisper, and Gift Delay), three planning tasks (Tower of Hanoi, Truck Loading, and Kitten Delivery), and a receptive vocabulary test (Peabody Picture Vocabulary Test [PPVT-3]). Multiple regression analyses indicated that two inhibition tasks (Bear/Dragon and Whisper) were significantly related to theory of mind after accounting for age, receptive vocabulary, and planning. In contrast, the planning tasks did not share unique variance with theory of mind. These results increase our understanding of the specific nature of executive function-theory of mind relations during early childhood.

Child Development↗

Executive function deficits associated with symptoms of schizotypy and obsessive-compulsive disorder.

Research suggests that executive dysfunction is seen both in disorders of the schizophrenia constellation and in obsessive-compulsive disorder (OCD), but that the patterns of executive deficits may differ. While disorders of the schizophrenia spectrum reflect impairment of functions such as integration of cognitive activities, a tendency to perseverate, and a failure to notice details (e.g. impairment associated with the dorsolateral prefrontal cortex), OCD may involve problems of impulse control and regulation of behavior, and an inability to maintain cognitive set (e.g. impairment associated with the orbitofrontal cortex). The present study examined differences between high-scorers on a measure of schizotypy, high-scorers on a measure of OCD, high-scorers on both schizotypy and OCD and a control group in performance on executive function tests. As expected, the OCD group demonstrated relative deficits on measures thought to reflect orbitofrontal functioning. However, contrary to expectations, the schizotypal group did not demonstrate deficits on neuropsychological tests thought to reflect dorsolateral prefrontal cortex functioning, and the combined group showed no executive impairment.

Adolescent↗

Individual differences in anterior cingulate/paracingulate morphology are related to executive functions in healthy males.

The neuropsychological correlates of inter-individual variations in cortical folding are poorly understood. Anterior cingulate (AC) cortex is one region characterized by considerable variability, particularly with respect to the paracingulate sulcus (PCS), which is present in only 30-60% of individuals and more commonly found in the left cerebral hemisphere. To investigate whether inter-individual differences in this PCS asymmetry are related to cognitive performance, we classified 30 healthy right-handed males as displaying either a leftward, rightward or symmetric pattern of folding based on the incidence and extent of the PCS in each hemisphere, and compared their performance on tasks engaging executive cognitive processes associated with frontal lobe function. We found that the more common leftward PCS asymmetry was associated with better performance across verbal and non-verbal executive tasks, but that PCS variability had no effect on tasks less dependent on executive functions. These results suggest that the leftward pattern of folding is associated with a non-specific performance advantage on cognitively demanding executive function tasks, possibly due to differences in functional interactions between AC/paracingulate cortex and connected frontal regions. It therefore appears that normal variations in brain morphology are associated with individual differences in cognitive abilities.

Adult↗

Apathy and executive function in depressed elderly.

Apathy and executive cognitive dysfunction (ECD) are important though conceptually different aspects of late-life depression. The primary objective of this study was to evaluate the relationship of apathy to ECD. The authors also evaluated the relationship of apathy and ECD to global cognitive impairment and word generation. Fifty-two elderly subjects with major depression and MMSE scores of 15 or greater were evaluated with apathy-related items from the Hamilton rating scale for depression (ApHRSD), the Executive Interview (EXIT), the Dementia Rating Scale (DRS), and the Controlled Oral Word Association test (COWA). ApHRSD scores were not significantly correlated with any of these variables. EXIT scores were correlated significantly with DRS and COWA. The results suggest that apathy and ECD may be independent of each other in some samples of elderly with late-life depression. Correlations may have been reduced by low variance for the variables of interest and by psychometric limitations of the ApHRSD.

Aged↗

Behavioral inhibition, sustained attention, and executive functions: constructing a unifying theory of ADHD.

Attention deficit hyperactivity disorder (ADHD) comprises a deficit in behavioral inhibition. A theoretical model is constructed that links inhibition to 4 executive neuropsychological functions that appear to depend on it for their effective execution: (a) working memory, (b) self-regulation of affect-motivation-arousal, (c) internalization of speech, and (d) reconstitution (behavioral analysis and synthesis). Extended to ADHD, the model predicts that ADHD should be associated with secondary impairments in these 4 executive abilities and the motor control they afford. The author reviews evidence for each of these domains of functioning and finds it to be strongest for deficits in behavioral inhibition, working memory, regulation of motivation, and motor control in those with ADHD. Although the model is promising as a potential theory of self-control and ADHD, far more research is required to evaluate its merits and the many predictions it makes about ADHD.

Affect↗

Executive functioning, memory, and learning in phenylketonuria.

The executive deficit hypothesis of treated phenylketonuria (PKU) suggests that dopaminergic depletion in the lateral prefrontal cortex leads to selective executive impairment. This was examined by comparing adults with PKU on a lifelong diet with a matched healthy control group. Those with PKU were impaired on selective and sustained attention, working memory (Self-Ordered Pointing), and letter fluency. However, they failed to show differential sensitivity to increased cognitive load on the attentional and working memory tasks, and they did not differ significantly on the remaining executive tasks (rule finding, inhibition, and multitasking). Nor did they differ significantly on recall or recognition memory. Overall, the findings provided little support for the executive deficit hypothesis. A possible explanation in terms of slowed information processing speed is explored.

Adolescent↗

Impairment of executive functions in boys with attention deficit/hyperactivity disorder.

The main aim of the present study is to compare the efficiency of executive control processes in 24 boys with attention deficit/hyperactivity disorder (ADHD) and 58 normal controls of similar age (between 8 and 11 years). Three reaction time (RT) paradigms were utilized: a dual task that requires coordination of two tasks responses, a shift task that makes it necessary to disengage attention from one task and engage into another one, and a stimulus-response spatial compatibility task that requires participants to inhibit a prepotent response. Another purpose of the study is to examine whether Barkley's (1997) executive dysfunction or Sergeant et al.'s (1999) resource allocation/arousal model best account for the behavioral deficits associated with ADHD. Examination of raw RT data showed significantly poorer performance in ADHD children with respect to age-matched controls on both the higher-level cognitive functions of executive control and on lower-level abilities (e.g., speed of processing) of all tasks of this study. However, using proportional transformations of raw RT data, we could demonstrate that, in addition to differences in processing speed, also executive control processes were significantly impaired in children with ADHD.

Attention Deficit Disorder with Hyperactivity↗

Executive function: the core feature of dementia?

Links between Alzheimer's disease (AD) and vascular dementia (VaD) have been examined, and this paper investigates the role of executive control function (ECF) within the dementia syndrome. 307 AD patients, 168 VaD patients and 208 controls were compared on tests of cognitive function. Results indicated that controls outperformed both patient groups (p < 0.001) on all tests. AD patients performed more poorly than VaD patients on 11 of the 18 cognitive tests (p < 0.05). Factor analysis of patient data indicated the existence of 3 factors generated from the battery of tests, relating to episodic memory, ECF and face recognition. It was primarily on tests of ECF that the AD and VaD groups did not differ significantly. It is concluded that ECF is a feature of cognition shared by the two pathologies, giving rise to an obligation to reconsider the current understanding of the core cognitive feature of dementia.

Aged↗

Functional and anatomical cortical underconnectivity in autism: evidence from an FMRI study of an executive function task and corpus callosum morphometry.

The brain activation of a group of high-functioning autistic participants was measured using functional magnetic resonance imaging during the performance of a Tower of London task, in comparison with a control group matched with respect to intelligent quotient, age, and gender. The 2 groups generally activated the same cortical areas to similar degrees. However, there were 3 indications of underconnectivity in the group with autism. First, the degree of synchronization (i.e., the functional connectivity or the correlation of the time series of the activation) between the frontal and parietal areas of activation was lower for the autistic than the control participants. Second, relevant parts of the corpus callosum, through which many of the bilaterally activated cortical areas communicate, were smaller in cross-sectional area in the autistic participants. Third, within the autism group but not within the control group, the size of the genu of the corpus callosum was correlated with frontal-parietal functional connectivity. These findings suggest that the neural basis of altered cognition in autism entails a lower degree of integration of information across certain cortical areas resulting from reduced intracortical connectivity. The results add support to a new theory of cortical underconnectivity in autism, which posits a deficit in integration of information at the neural and cognitive levels.

Adult↗

Thalamus and language: interface with attention, memory and executive functions.

Subcortical structures are in a strategic functional position within the cognitive networks. Their lesion can interfere with a great number of functions. We studied six patients with thalamic vascular lesions (three left sided, two right sided and one bilateral), to characterize their repercussion in the communicative abilities and the interface between language alterations and other cognitive abilities, as attention, memory and frontal executive. All patients were evaluated through a functional interview (discourse analysis), and the following batteries: Boston Diagnostic Aphasia Examination, Boston Naming Test, Token Test, Benton Visual Retention Test, Trail Making, Wisconsin Card Sorting and frontal scripts. All patients performed MRI and five underwent SPECT. Results show that these patients present impairment in several cognitive domains, especially attention and executive functions (working memory, planning and self-monitoring); those with right lesions have an additional visuospatial impairment. Such alterations interfere with language abilities, and this fact must be considered in the rehabilitation efforts.

Adult↗