Executive function deficits in persons with mild cognitive impairment: a study with a Tower of London task.

This study assessed executive functions in persons with mild cognitive impairment (MCI) using the Tower of London (TOL). A second objective was to study the impact of three types of problem selected according to the presence or absence of a "trigger." A trigger (T) is an incitation to the participant, at the first move, to move a ball to its final position according to the model. A positive trigger (T+) is helpful, while a negative trigger (T-) creates an obstruction. Some problems have no trigger (N). This study includes 81 participants with MCI. After follow-up, one year later, two subgroups were distinguished: (a) 51 (63%) participants did not convert or decline (stable MCI); (b) 30 (37%) participants showed significant decline or progressed to dementia (decliner MCI). Persons with MCI were compared to an older adult group matched with respect to sex, age, and education. For the successes, there was a significant group difference between the three types of problem. The post hoc analysis showed that T+ took significantly less time than N or T-. There were significantly more successes for T+ than N, and these two types of problem had more success than T-. For "total number of moves," there was no significant difference between the groups. In post hoc analysis, T- involved more moves than N or T+. In qualitative analysis, T- MCI decliners produced significantly more rule breakings than the stable MCI and controls. A dysfunction in self-monitoring is a characteristic feature of persons with MCI.

A generalizability study of the instrumental activities of daily living profile.

OBJECTIVE: To establish generalizability estimates of the Instrumental Activities of Daily Living (IADL) Profile when administered to persons with a moderate or severe traumatic brain injury (TBI) within their home and community environment. DESIGN: Generalizability theory was used to estimate generalizability and dependability coefficients as well as the relative contribution of identified sources of measurement error to total measurement error. Decision studies were used to enable the investigators to determine the optimal measurement design. SETTING: The IADL Profile was administered in subjects' homes and community environments. PARTICIPANTS: Convenience sample of adults with a moderate or severe TBI (N=30, aged 16-65y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: IADL Profile scores include 6 factor scores (going to the grocery store/shopping for groceries, having a meal with guests/cleaning up, putting on outdoor clothing, obtaining information, making a budget, and preparing a hot meal) and 1 total score. RESULTS: The greatest sources of measurement error were the subject-item interactions (3-random-facet design) and the subject-rater interactions (2-random-facet design). One hundred percent of generalizability coefficients of factor scores indicated acceptable to excellent reliability. Indices of dependability confirmed that 1 evaluator could reliably score the tool on a single occasion after having received a 3-day training workshop. CONCLUSIONS: The IADL Profile administered to persons with a moderate or severe TBI provides occupational therapists with a reliable set of measures of IADL independence capable of both capturing and analyzing the complex interactions between personal and environmental factors.

The IADL profile: development, content validity, intra- and interrater agreement.

BACKGROUND: Occupational therapists are frequently asked to document the interplay between individuals' neuropsychological deficits and the requirements of their daily lives. PURPOSE: The present study was designed to develop and validate a measure of independence in everyday functioning that considers recent advances in research regarding the ecological assessment of executive functions. METHOD: Experts (n=8) judged the IADL Profile's content validity and the tool was pilot tested with the target population (n=8). To document the tool's reliability, 30 patients aged 16 to 65 with moderate or severe TBI were recruited. A trained examiner administered the IADL Profile, and three trained judges rated video recordings on two occasions. RESULTS: An eight-task (29-item) test was developed. Comparing ratings of four raters, 95 percent of kappa coefficients indicated moderate to almost perfect agreement, and 94% showed almost perfect intrarater agreement. IMPLICATIONS: The IADL Profile provides occupational therapists with a set of measures of IADL independence with strong preliminary evidence of reliability.

Performance of humans vs. exploration algorithms on the Tower of London Test.

The Tower of London Test (TOL) used to assess executive functions was inspired in Artificial Intelligence tasks used to test problem-solving algorithms. In this study, we compare the performance of humans and of exploration algorithms. Instead of absolute execution times, we focus on how the execution time varies with the tasks and/or the number of moves. This approach used in Algorithmic Complexity provides a fair comparison between humans and computers, although humans are several orders of magnitude slower. On easy tasks (1 to 5 moves), healthy elderly persons performed like exploration algorithms using bounded memory resources, i.e., the execution time grew exponentially with the number of moves. This result was replicated with a group of healthy young participants. However, for difficult tasks (5 to 8 moves) the execution time of young participants did not increase significantly, whereas for exploration algorithms, the execution time keeps on increasing exponentially. A pre-and post-test control task showed a 25% improvement of visuo-motor skills but this was insufficient to explain this result. The findings suggest that naive participants used systematic exploration to solve the problem but under the effect of practice, they developed markedly more efficient strategies using the information acquired during the test.

Daily functioning and information-processing skills among persons with schizophrenia.

OBJECTIVES: This study aimed to describe the limitations in information-processing skills observed among persons with schizophrenia performing daily tasks and to explore whether subgroups of participants have similar profiles based on these functional limitations. METHODS: Eighty-two participants with schizophrenia living in the community were assessed during their performance of a daily activity (meal preparation). Measures included a performance-based assessment for evaluating information-processing skills-the Perceive, Recall, Plan, and Perform System of Task Analysis-community functioning and symptom assessments, and neuropsychological tests from the Cambridge Neuropsychological Test Automated Battery. Research participants were classified as having high efficiency or low efficiency according to their score on the performance-based assessment and were compared on the functional, cognitive, and symptoms variables. RESULTS: Participants committed various errors, and functional limitations, namely problematic information-processing skills in the perceive, recall, and plan quadrants, were observed during the daily task performance. Participants from the high-efficiency group were more independent in their living skills and more successful in attaining residential independence compared with participants from the low-efficiency group. The only cognitive test that differentiated both groups was the visuospatial associative learning test. No differences were found in the severity of symptoms. CONCLUSIONS: Findings suggest that both performance in a daily task and memory-and specifically associative learning capacity-provide key information for the level of residential independence. Interventions aiming for the efficient use of information-processing skills during daily tasks among persons with schizophrenia should be carried out accordingly.

The criterion-related validity of the IADL Profile with measures of executive functions, indices of trauma severity and sociodemographic characteristics.

PRIMARY OBJECTIVE: To examine relationships between classical measures of executive functions (EF) and indices of traumatic brain injury (TBI) severity with the IADL Profile, a new performance-based measure of independence in instrumental activities of daily living (IADL) based on EF. This study hypothesized the presence of correlations between classical tests of EF and the IADL Profile, as the latter aims to establish whether the subject's main difficulties pertain to goal formulation, planning, carrying out the task and/or attaining the initial task goal; all important components of EF. METHODS AND PROCEDURES: One hundred subjects with a moderate/severe TBI aged 16-65 years (convenience sample) were recruited. Subjects were tested with the IADL Profile and three measures of EF within their home environment. Data was analysed using Pearson correlations, t-tests and multiple stepwise regressions. RESULTS: Post-traumatic amnesia and working memory emerged as the major determinants of IADL Profile scores. Together, indices of injury severity, measures of EF, education, age and environmental factors accounted for 12-28% of the variance in IADL Profile scores. CONCLUSIONS: This study has shown that the IADL Profile's non-structured approach permits the observation of a broad range of behaviours related to EF deficits and thus provides a closer approximation of the person's independence in IADL. Further study is required to demonstrate the IADL Profile's ability to inform more targeted treatment interventions.

Use of the Perceive, Recall, Plan and Perform System of Task Analysis for persons with schizophrenia: a preliminary study.

BACKGROUND/AIM: Task analysis that targets information processing skills is an essential tool to understanding difficulties encountered by people with schizophrenia in their daily activities. The purpose of this preliminary study was to explore the use of the Perceive, Recall, Plan and Perform (PRPP) System of Task Analysis for this clientele. The specific objectives were to describe information processing difficulties as measured by the PRPP and to examine preliminary evidence of construct validity and interrater reliability. METHODS: In the first part of this study, 10 participants with schizophrenia living in the community were assessed using the PRPP during both a simple and a complex meal preparation task. Community functioning was measured using the Independent Living Skills Survey. In the second part, interrater reliability was appraised using three trained raters, who scored 15 participants preparing the complex meal preparation task. RESULTS: Analysis of performance demonstrates that people with schizophrenia have difficulties especially in the Perceive and Plan quadrants of the PRPP and are more challenged in the complex task. The PRPP total score for the complex task is strongly related to the community functioning score. Results indicate good interrater reliability for the PRPP total score and moderate interrater reliability for the quadrant scores. CONCLUSION: Despite the small sample size, results from this preliminary study support the use of the PRPP System of Task Analysis to further explore the impact cognitive deficits have on daily task performance and thus on community functioning in people with schizophrenia.

Daily activities, cognition and community functioning in persons with schizophrenia.

OBJECTIVE: This cross-sectional study explored the relationships between daily activity performance, attention, memory, executive functions and community functioning in people with schizophrenia. More specifically, this study attempted to verify the hypothesis that functional limitations in the performance of daily activities negatively affect community functioning in people with schizophrenia. METHODS: Eighty-two individuals with schizophrenia living in the community were recruited for the study. The Perceive, Recall, Plan and Perform (PRPP) System of Task Analysis was used to assess participants' functional capacity during a meal preparation task. Visuo-spatial associative memory, spatial working memory, planning, visuo-motor coordination, and selective attention were evaluated as well. Community functioning was assessed with the Independent Living Skills Survey (ILSS) and the Multnomah Community Ability Scale (MCAS). RESULTS: Correlations revealed significant associations between functional capacity and visuo-spatial associative learning, spatial working memory, planning and negative symptoms. Planning skills during meal preparation were found to be associated with MCAS. After regression analyses, only visuo-spatial memory, negative symptoms, education and familiarity with meal preparation explained variation in functional capacity. CONCLUSIONS: The findings of the current study suggest that visuo-spatial associative learning, negative symptoms, education and familiarity with task are among the important factors for functional capacity. Planning skills necessary for efficient task performance were also found to be those most determinant for community functioning. Rehabilitation interventions should consider these underlying strength and deficits when developing strategies to help people with schizophrenia build functional skills essential for community living.

The factorial validity and internal consistency of the Instrumental Activities of Daily Living Profile in individuals with a traumatic brain injury.

The objective of the study was to investigate the factorial validity and internal consistency of the Instrumental Activities of Daily Living (IADL) Profile. A group of 96 patients aged 16 to 65 years, with moderate to severe traumatic brain injuries, was recruited from 12 rehabilitation hospitals in Quebec. The IADL Profile was administered by an occupational therapist in each subject's home and community environment. Principal axis factoring and confirmatory factor analysis provide preliminary support for six correlated factors (F): (F1) going to grocery store/shopping for groceries, (F2) having a meal with guests/cleaning up, (F3) putting on outdoor clothing, (F4) obtaining information, (F5) making a budget, (F6) preparing a hot meal for guests. Total explained variance was 73.6%. Cronbach's alpha analysis revealed high to very high internal consistency for all scales ranging from .81 to .98; internal consistency of the total scale was very high (0.95). The findings suggest that the IADL Profile is a promising means of documenting both IADL independence and the repercussions of executive function deficits on everyday tasks in real-world environments.

Wayfinding in the blind: larger hippocampal volume and supranormal spatial navigation.

In the absence of visual input, the question arises as to how complex spatial abilities develop and how the brain adapts to the absence of this modality. We explored navigational skills in both early and late blind individuals and structural differences in the hippocampus, a brain region well known to be involved in spatial processing. Thirty-eight participants were divided into three groups: early blind individuals (n = 12; loss of vision before 5 years of age; mean age 33.8 years), late blind individuals (n = 7; loss of vision after 14 years of age; mean age 39.9 years) and 19 sighted, blindfolded matched controls. Subjects undertook route learning and pointing tasks in a maze and a spatial layout task. Anatomical data was collected by MRI. Remarkably, we not only show that blind individuals possess superior navigational skills than controls on the route learning task, but we also show for the first time a significant volume increase of the hippocampus in blind individuals [F(1,36) = 6.314; P < or = 0.01; blind: mean = 4237.00 mm(3), SE = 107.53; sighted: mean = 3905.74 mm(3), SE = 76.27], irrespective of whether their blindness was congenital or acquired. Overall, our results shed new light not only on the construction of spatial concepts and the non-necessity of vision for its proper development, but also on the hippocampal plasticity observed in adult blind individuals who have to navigate in this space.

Effect of navigation direction on the dual-task of counting backward during blind navigation.

Blind navigation towards a remembered target is associated with large direction errors when executed with a side stepping walking pattern. To investigate whether sideways navigation requires higher attention resource than forward navigation, a dual-task paradigm of backward counting during blind navigation was used. The objectives were to determine the effect of this dual-task on navigation errors, gait velocity and the rate of backward counting and to establish whether this effect is larger during sideways than forward navigation. A group of 17 subjects participated. The primary task was to navigate without vision towards previously seen targets located on the floor 8m away in four directions (ahead, behind, to the right or left) and to stop at the place the target was presumed to be. Forward, backward and side stepping gait patterns were used to reach corresponding targets. The secondary task was to count backwards in steps of three. The dual-task was to perform blind navigation while counting backwards. The rate of backward counting was significantly decreased in the dual-task relative to a controlled sitting condition (p<0.05), but this reduction was similar among navigation directions. Navigation errors were not changed between navigation only and dual-task. Gait velocity was significantly slower in the dual-task than in navigation only (p<0.05). This suggests that counting backward while navigating without vision towards a remembered target exceeded the subjects' attention capacity. However, sideways navigation did not seem to require more attention than forward navigation, even though navigation was much less precise in sideways than forward navigation.

Tactile-'visual' acuity of the tongue in early blind individuals.

This study compares the 'tactile-visual' acuity of the tongue for 15 early blind participants with that of 24 age-matched and sex-matched sighted controls. Snellen's tumbling E test was used to assess 'visual' acuity using the tongue display unit. The tongue display unit is a sensory substitution device that converts a visual stimulus grabbed by a camera into electro-tactile pulses delivered to the tongue via a grid made out of electrodes. No overall significant difference was found in thresholds between early blind (1/206) and sighted control (1/237) participants. We found, however, a larger proportion of early blind in the two highest visual acuity categories (1/150 and 1/90). These results extend earlier findings that it is possible to measure visual acuity in the blind individuals using the tongue. Moreover, our data demonstrate that a subgroup of early blind participants is more efficient than controls in conveying visual information through the tongue.

Reproducibility of distance and direction errors associated with forward, backward, and sideway walking in the context of blind navigation.

The ability to navigate without vision towards a previously seen target has been extensively studied, but its reliability over time has yet to be established. Our aims were to determine distance and direction errors made during blind navigation across four different directions involving three different gait patterns (stepping forward, stepping sideway, and stepping backward), and to establish the test-retest reproducibility of these errors. Twenty young healthy adults participated in two testing sessions separated by 7 days. They were shown targets located, respectively, 8 m ahead, 8 m behind, and 8 m to their right and left. With vision occluded by opaque goggles, they walked forward (target ahead), backward (target behind), and sideway (right and left targets) until they perceived to be on the target. Subjects were not provided with feedback about their performance. Walked distance, angular deviation, and body rotation were measured. The mean estimated distance error was similar across the four walking directions and ranged from 16 to 80 cm with respect to the 8 m target. In contrast, direction errors were significantly larger during sideway navigation (walking in the frontal plane: leftward, 10 degrees +/- 15 degrees deviation; rightward, 18 degrees +/- 13 degrees) than during forward and backward navigation (walking in the sagittal plane). In general, distance and direction errors were only moderately reproducible between the two sessions [intraclass correlation coefficients (ICCs) ranging from 0.682 to 0.705]. Among the four directions, rightward navigation showed the best reproducibility with ICCs ranging from 0.607 to 0.726, and backward navigation had the worst reliability with ICCs ranging from 0.094 to 0.554. These findings indicate that errors associated with blind navigation across different walking directions and involving different gait patterns are only moderately to poorly reproducible on repeated testing, especially for walking backward. The biomechanical constraints and increased cognitive loading imposed by changing the walking pattern to backward stepping may underlie the poor performance in this direction.

A delivery device for presentation of tactile stimuli during functional magnetic resonance imaging.

We describe a novel stimulus delivery system designed to present tactile stimuli to a subject in the tunnel of a magnetic resonance imaging (MRI) system. Using energy from an air-driven piston to turn a wheel, the device advances a conveyor belt with a pre-determined sequence of stimuli that differ in their spatial features into the tunnel of the MRI. The positioning of one or several stimulus objects in a window near the subject's hand is controlled by a photoelectric device that detects periodic openings in the conveyor belt. Using this electric signal to position each presentation avoids cumulative positioning errors and provides a signal related to the progression of the experiment. We used a series of shapes that differed in their spatial features but the device could carry stimuli with a diversity of shapes and textures. This flexibility allows the experimenter to design a wide variety of psychophysical experiments in the haptic world and possibly to compare and contrast these stimuli with the cognitive treatment of similar stimuli delivered to the other senses. Appropriate experimental design allows separation of motor, sensory and memory storage phases of mental processes.

Differential diagnosis between borderline personality disorder and organic personality disorder following traumatic brain injury.

Organic personality disorder (OPD) is the traditional diagnostic category used to account for personality disturbances after traumatic brain injury (TBI). The recent use of Axis-II personality disorders, notably borderline personality disorder (BPD), has appeared in the TBI literature as an alternative to OPD. This would presumably offer a better description and understanding of the multiple clinical manifestations of these personality changes and disorders. This article offers a view that it is possible and fruitful to use both diagnoses in a complementary manner. An accurate recognition of the respective phenomenologies of both BPD and OPD is a key factor in achieving a differential diagnosis, including, if required, a dual diagnosis. The phenomenology of both conditions in reference to DSM-IV criteria is compared and illustrated through two clinical vignettes.

Impact of vision on the development of topographical orientation abilities.

The current experiment examined the importance of visual input on the construction of inner spatial representations. Early and late-onset blind and paired control participants performed a tactile spatial orientation task. No significant group differences were observed, indicating that the blind can represent space. More errors, however, were committed by the early blind than by the late blind and sighted individuals in portions of the task that involved mental rotation skills, suggesting a potential facilitating role for vision in the proper development of spatial constructs.

Inhibition and object relations in borderline personality traits after traumatic brain injury.

This study aims to assess the nature and severity of borderline traits after traumatic brain injury (TBI). Thirty subjects with moderate or severe TBI were compared to 30 normal controls on the Revised Diagnostic Interview for Borderlines (DIB-R), a dimensional measure of borderline traits, the Go-no go inhibition task, the Complexity of Representations of People and Affect-Tone Relationships Paradigms, two scales from the Social Cognition and Object Relations Scale (SCORS) evaluating the quality of object relations, an estimation of pre-morbid borderline severity, the Beck Depression Inventory (BDI) and various neuropsychological measures. Results indicate that TBIs present more borderline symptoms and traits than controls. However, the severity of borderline symptomatology remains comparatively low for the vast majority. As expected, the TBI group showed a poorer performance on the Go-no go task, a characteristic neuropsychological inhibition deficit. Yet, both samples present similar profiles on the SCORS. Finally, the DIB-R was correlated with the Affect-Tone scale, the BDI and with the pre-morbid severity estimation. Results suggest that post-TBI borderline traits remain rare and relate more to the affective quality of object relations, negative affects and pre-morbid borderline pathology than inhibition deficits.

Wayfinding in familiar and unfamiliar environments in a case of progressive topographical agnosia.

A 71-year-old right-handed man (F.G.) presents with prosopagnosia and with an inability to recognize famous and familiar buildings. Despite his deficit, F.G. obtained normal scores on neuropsychological tests of executive functions, language, praxis and primary visuoperceptual skills. Brain MRI showed atrophy predominantly in the right temporal lobe, particularly in the fusiform gyrus and the parahippocampal cortex. The present study investigated F.G.'s ability to orient himself in familiar and new environments. His wayfinding abilities in a familiar environment (i.e., his hometown) were preserved despite an inability to recognize familiar and famous buildings, monuments and landmarks in this environment. Wayfinding was achieved through a heavy reliance on written indications (e.g., names of restaurants and streets), preservation of a pre-existing cognitive map of this familiar environment, and normal executive functions necessary to plan the execution of a given trajectory. In an unfamiliar environment, F.G.'s topographical agnosia resulted in severe wayfinding difficulties and in the inability to build an adequate cognitive spatial representation. F.G.'s topographical agnosia results from a high-level visuoperceptual deficit, characterized by an inability to access a global configuration of complex visual stimuli such as familiar and famous monuments, and an over-reliance on the processing of local features.

Evidencing inhibitory deficits in Alzheimer's disease through interference effects and shifting disabilities in the Stroop test.

To investigate the contribution of inhibitory deficits in the deterioration of executive function abilities in Alzheimer's disease (AD), a modified version of the Stroop test was submitted to 44 AD patients and 44 elderly controls. Half of the subjects performed successively the Interference Stroop task, the two control tasks and the Reverse Stroop task, and half performed the Reverse Stroop task, the control tasks and finally the Interference Stroop task. This experimental design allowed to assess inhibitory deficits by measuring classical interference effects but also by measuring the ability to shift between tasks instructions. Results confirmed AD patients' difficulty in suppressing the automatic response of reading in the Interference Stroop task. Moreover, AD patients presented worsened performances in the Interference task when administered after the Reverse task, and a Reverse Stroop effect was found in the patients revealing their difficulty in suppressing a previously relevant rule in order to learn a new one.

Correlation between evening and morning waking EEG and spatial orientation.

The prefrontal, frontal, and parietal EEG of 16 healthy young adults (seven men, nine women; age=22.57+/-4.2) was recorded during the waking state (eyes closed) in the evening before and the morning following a second consecutive night spent in a sleep laboratory. Following the morning EEG recording session, participants were tested in a human-size maze upon five learning trials of a four-intersection route. Results on the fifth trial served as the learning index. We found a significant positive correlation between time taken to carry out the route and prefrontal, frontal EEG alpha-2 (10.0-12.75 Hz), and sigma (11.5-14.5 Hz) frequency bands. We also found that prefrontal and frontal theta activity correlated negatively with number of errors. No correlation was found between performance and neither alpha-1 (8.0-9.75 Hz) nor parietal EEG activity. These results confirm the involvement of the prefrontal and frontal cortices in the mechanisms responsible for modulating spatial orientation.