Deficits In Orientation Research Articles

Unreliable association between self-reported sense of direction and peripheral vestibular function.

Uni- or bilateral peripheralvestibular impairment causes objective spatial orientation deficits, which can be measured using pen-and-paper-tests or sensorimotor tasks (navigation or pointing). For patients' subjective orientation abilities, questionnaires are commonly used (e.g., Santa Barbara sense of direction scale [SBSODS]). However, the relationship between subjective assessment of spatial skills and objective vestibular function has only been scarcely investigated. A total of 177 patients (mean age 57.86±17.53 years, 90 females) who presented in our tertiary Center for Vertigo and Balance Disorders underwent neuro-otological examinations, including bithermal water calorics, video head impulse test (vHIT), and testing of the subjective visual vertical (SVV), and filled out the SBSODS (German version). Correlation analyses and linear multiple regression model analyses were performed between vestibular test results and self-assessment scores. Additionally, groupwise vestibular function for patients with low, average, and high self-report scores was analyzed. Forty-two patients fulfilled the diagnostic criteria for bilateral vestibulopathy, 93 for chronic unilateral vestibulopathy (68 unilateral caloric hypofunction and 25 isolated horizontal vestibulo-ocular reflex deficits), and 42 patients had normal vestibular test results. SBSODS scores showed clear sex differences with higher subjective skill levels in males (mean score males: 4.94±0.99, females 4.40±0.94; Student's t-test: t-3.78, p<.001***). No stable correlation between objective vestibular function and subjective sense of spatial orientation was found. A multiple linear regression model could not reliably explain the self-reported variance. The three patient groups with low, average, and high self-assessment-scores showed no significant differences of vestibular function. Self-reported assessment of spatial orientation does not robustly correlate with objective peripheral vestibular function. Therefore, other methods of measuring spatial skills in real-world and virtual environments are required to disclose orientation deficits due to vestibular hypofunction.

Evaluation of the cognitive, physiological, and biomarker effects of heavy metal exposure in Wistar rats.

Individuals exposed to heavy metals are known to experience physiological and biochemical changes, which raise questions regarding possible health effects. In our earlier research, significant concentrations of vanadium (V), mercury (Hg), cadmium (Cd), and arsenic (As) were found in food and medical packaging materials. This study aimed to evaluate the cognitive, physiological, and biomarker effects of select heavy metal exposure in Wistar rats. Over a 13-week period, five groups of rats (six rats per group, with both males and females) were assessed to study the effects of oral exposure to V, Hg, Cd, and As. The study focused on evaluating physiological, cognitive, and biochemical markers, with the results compared to those of a control group. Comparing all groups of rats treated with heavy metals, the study revealed significant deficits in learning and spatial orientation (water maze test); rats treated with V, Cd, and Hg showed signs of depression. Rats treated with As also showed signs of hyperactivity, which may indicate a connection to attention-deficit hyperactivity disorder (rat tail suspension test). The groups exposed to different heavy metals varied in their physiological (water and food intake, urine and feces output) and biochemical responses (enzyme-linked immunosorbent assay, prostate-specific antigen, T3, T4, thyroid-stimulating hormone, carcinoembryonic antigen, and blood glucose analysis), with Hg exhibiting the strongest impacts. Rats given Hg showed signs of hypothyroidism, such as increased food intake and weight gain. This study clarifies the complex relationships between exposure to heavy metals and various biological systems, shedding light on their potential health impacts. The findings provide insight into the effects of heavy metals on neural and thyroid tissues, as well as their propensity to cause cellular dedifferentiation. However, the study has certain limitations, such as the relatively short duration of exposure and the use of only a few selected biomarkers. Future research should focus on long-term exposure studies, incorporate a broader range of biomarkers, and explore the underlying mechanisms at a molecular level to better understand the full spectrum of health risks associated with heavy metal exposure.

Is Virtual Reality Orientation Therapy Useful to Optimize Cognitive and Behavioral Functioning Following Severe Acquired Brain Injury? An Exploratory Study.

Severe acquired brain injury (SABI) is a leading cause of death and disability, and it is defined as a brain injury that occurs after birth due to traumatic or non-traumatic causes. Reality orientation therapy (ROT) uses repeated time-place-person orientation and meaningful stimuli to develop a better understanding of the environment and has great potential as an effective strategy to improve cognitive and behavioral functioning. This study aims to investigate the feasibility and potential effects of virtual reality orientation therapy (VR-rot) on optimizing cognitive and behavioral functioning and depressive symptoms post-SABI. Forty patients with SABI were enrolled from October 2022 to December 2023 and divided into two groups: the experimental group (EG, n = 20) received VR_rot, while the control group (CG, n = 20) received standard ROT (S_rot). All patients were evaluated with a psychometric battery, including the Mini-Mental State Examination (MMSE) and the Hamilton Rating Scale for Depression (HRS-D), administered before (T0) and after the end (T1) of rehabilitation. Within-group comparisons indicated a statistically significant change in MMSE scores from T0 to T1 in the EG and CG, with the EG showing a greater improvement than the CG. Regarding HRS-D scores, the EG showed a statistically significant change. VR-ROT could be a valuable tool for improving cognitive-behavioral functioning in SABI patients. The VRRS can help reduce depressive symptoms and improve the reality orientation deficit caused by traumatic brain injury and stroke on brain tissue. This study highlights the benefits of virtual reality.

Improving orientation with respect to gravity enhances balance and gait recovery after stroke: DOBRAS cohort

BackgroundLateropulsion is a deficit in body orientation with respect to gravity, frequent after stroke. Although it is a primary factor affecting mobility, the impact of its attenuation on balance and gait recovery has never been investigated. Moreover, most studies on the lateropulsion time-course focus on severe forms suspected to have a poor recovery, which is not proven. ObjectivesTo investigate lateropulsion attenuation and test 2 hypotheses: 1) lateropulsion attenuation greatly contributes to balance and gait recovery and 2) severe forms of lateropulsion recover slower than moderate forms. MethodsThis longitudinal study involved individuals included in the Determinants of Balance Recovery After Stroke (DOBRAS) cohort, after a first-ever hemispheric stroke, with data collected on day 30 (D30), D60 and D90 post-stroke. Body orientation with respect to gravity was assessed using the Scale for Contraversive Pushing (both scores and severity grouping), in parallel with balance (Postural Assessment Scale for Stroke) and gait (modified Fugl-Meyer Gait Assessment). ResultsAmong the 106 eligible individuals (mean age 66.5 [SD 9.7] years), on D30, 43 (41%) were considered upright and 63 (59%) showed lateropulsion: 30 (28%) moderate and 33 (31%) severe. Most individuals with lateropulsion (73%) improved their body orientation, progressing from severe to moderate lateropulsion, or becoming upright. However, half were still not upright on D90. The improvement in body orientation had a large impact on mobility, especially in individuals with severe lateropulsion, in whom it explained about 50% of balance and gait recovery between D30 and D60, then 20% (D60-D90). For moderate lateropulsion, its attenuation explained about 20% of balance and gait recovery until D90. Lateropulsion attenuation was not slower in individuals with severe forms. ConclusionsLateropulsion attenuation enhances balance and gait recovery in individuals after stroke suggesting that specific rehabilitation of body orientation with respect to gravity might help to recover mobility. RegistrationNCT03203109

The Impact of Spatial Orientation Changes on Driving Behavior in Healthy Aging.

Global cognitive changes in older age affect driving behavior and road safety, but how spatial orientation differences affect driving behaviors is unknown on a population level, despite clear implications for driving policy and evaluation during aging. The present study aimed to establish how spatial navigation changes affect driving behavior and road safety within a large cohort of older adults. Eight hundred and four participants (mean age: 71.05) were recruited for a prospective cohort study. Participants self-reported driving behavior followed by spatial orientation (allocentric and egocentric) testing and a broader online cognitive battery (visuomotor speed, processing speed, executive functioning, spatial working memory, episodic memory, visuospatial functioning). Spatial orientation performance significantly predicted driving difficulty and frequency. Experiencing more driving difficulty was associated with worse allocentric spatial orientation, processing speed, and source memory performance. Similarly, avoiding challenging driving situations was associated with worse spatial orientation and episodic memory. Allocentric spatial orientation was the only cognitive domain consistently affecting driving behavior in under 70 and over 70 age groups, a common age threshold for driving evaluation in older age. We established for the first time that worse spatial orientation performance predicted increased driving difficulty and avoidance of challenging situations within an older adult cohort. Deficits in spatial orientation emerge as a robust indicator of driving performance in older age, which should be considered in future aging driving assessments, as it has clear relevance for road safety within the aging population.

Evaluating the ergonomic deficiencies in computer workstations and investigating their correlation with reported musculoskeletal disorders and visual symptoms among computer users in Bangladeshi university

BackgroundNowadays, computer users are facing musculoskeletal disorders (MSDs) and visual symptoms. Prolonged sitting in inappropriate, awkward, and static postures on the computer workstation may cause musculoskeletal disorders (MSDs). Similarly, inappropriate placement of monitors, illumination, and other factors such as prolonged usage of computers are related to visual symptoms. Objective: This study aims to evaluate the ergonomic deficiencies of computer workstations and their correlation with MSDs and visual symptoms. Methods: This study involved 271 university employees from a Bangladeshi engineering university. Ergonomic deficiencies were evaluated through direct observations and Occupational Safety and Health Administration checklists. In addition, the Nordic Musculoskeletal Questionnaire was used to assess the prevalence of MSDs and visual discomforts. Binary Logistic Regression (BLR) analysis was also used to examine the correlation between musculoskeletal symptoms and ergonomic deficiencies. Results: Results showed serious deficiencies in workstation setup, seating arrangement, monitor orientations, keyboard orientations, other input device orientations, and accessory setup. Employees reported that the MSDs in different body regions during the last 12 months including lower back (62 %), upper back (53 %), shoulders (47 %), and neck (25 %). Moreover, itchy eyes (69 %), tired eyes (83 %), and unclear vision (56.83 %) were the most common visual discomforts or visual symptoms among the participants. Results also revealed that monitor ergonomics and its orientation deficits were significantly associated with visual discomforts. Gender, job type, age, BMI, work experience, duration of computer work, and beak taking after 2 h were the independent variables reliably predicting the MSDs and visual symptoms. Conclusion: It is evident that MSDs and visual symptoms were associated with computer workstation deficiencies and other work-related factors.

A review of the impairments, preserved visual functions, and neuropathology in 21 patients with visual form agnosia – A unique defect with line drawings

We present a comprehensive review of the rare syndrome visual form agnosia (VFA). We begin by documenting its history, including the origins of the term, and the first case study labelled as VFA. The defining characteristics of the syndrome, as others have previously defined it, are then described. The impairments, preserved aspects of visual perception, and areas of brain damage in 21 patients who meet these defining characteristics are described in detail, including which tests were used to verify the presence or absence of key symptoms. From this, we note important similarities along with notable areas of divergence between patients. Damage to the occipital lobe (20/21), an inability to recognise line drawings (19/21), preserved colour vision (14/21), and visual field defects (16/21) were areas of consistency across most cases. We found it useful to distinguish between shape and form as distinct constructs when examining perceptual abilities in VFA patients. Our observations suggest that these patients often exhibit difficulties in processing simplified versions of form. Deficits in processing orientation and size were uncommon. Motion perception and visual imagery were not widely tested for despite being typically cited as defining features of the syndrome – although in the sample described, motion perception was never found to be a deficit. Moreover, problems with vision (e.g., poor visual acuity and the presence of hemianopias/scotomas in the visual fields) are more common than we would have thought and may also contribute to perceptual impairments in patients with VFA. We conclude that VFA is a perceptual disorder where the visual system has a reduced ability to synthesise lines together for the purposes of making sense of what images represent holistically.

Localization of a Medial Temporal Lobe-Precuneus Network for Time Orientation.

Time orientation is a fundamental cognitive process in which one's personal sense of time is matched with a universal reference. Time orientation is commonly assessed through mental status examination, yet its neural correlates remain unclear. Large lesions have been associated with deficits in time orientation, but the regional anatomy implicated in time disorientation is not well established. The current study investigates the anatomy of time disorientation and its network correlates in patients with focal brain lesions. Time orientation was assessed 3 months or more after lesion onset using the Benton Temporal Orientation Test (BTOT) in 550 patients with acquired, focal brain lesions, 39 of whom were impaired. Multivariate lesion-symptom mapping and lesion network mapping were used to evaluate the anatomy and networks associated with time disorientation. Performance on a variety of neuropsychological tests was compared between the time oriented and time disoriented group. Lesion-symptom mapping showed that lesions of the precuneus, medial temporal lobes (MTL), and occipito-temporal cortex were associated with time disorientation (r = 0.264, p < 0.001). Lesion network mapping using normative connectome data demonstrated that these regional findings occurred along a network that includes white and gray matter connecting the precuneus and MTL. There was a strong behavioral and anatomical association of time disorientation with memory impairment, such that the 2 processes could not be fully disentangled. We interpret these findings as novel evidence for a network involving the precuneus and the medial temporal lobe in supporting time orientation. ANN NEUROL 2023;94:421-433.

Evaluation of cognitive disengagement syndrome in children with obsessive-compulsive disorder: Clinical implications.

Cognitive disengagement syndrome (CDS) has been found to be associated with internalizing symptoms. Yet, no study thus far has focused on whether there is an association between obsessive-compulsive disorder (OCD) and CDS. The purpose of this study is to examine the symptom frequency and clinical implications of CDS in children with OCD. The study included sixty-one children with OCD and sixty-six typically developing children. Children were evaluated by a semi-constructed diagnosis interview, Obsessive-Compulsive Inventory, Barkley Child Attention Scale, and Stroop test. The frequency of elevated symptoms of CDS, and total time, total error, and total correction scores of the Stroop test were significantly higher in the OCD group compared to the controls. Elevated CDS symptoms were significantly associated with higher OCD symptom prevalence and poorer performance on the Stroop Test. Moreover, poor insight, hoarding symptoms, mental compulsions, and ADHD comorbidity were significantly higher in those with elevated CDS symptoms than in those without CDS in the OCD group. The findings of this study provide clinical implications that CDS symptoms may contribute to deficits in attentional orientation, conceptual flexibility, and cognitive processing speed in OCD.

A cortico-collicular circuit for orienting to shelter during escape.

When faced with predatory threats, escape towards shelter is an adaptive action that offers long-term protection against the attacker. Animals rely on knowledge of safe locations in the environment to instinctively execute rapid shelter-directed escape actions1,2. Although previous work has identified neural mechanisms of escape initiation3,4, it is not known how the escape circuit incorporates spatial information to execute rapid flights along the most efficient route to shelter. Here we show that themouse retrosplenial cortex (RSP) and superior colliculus (SC) form a circuit that encodes the shelter-direction vector and is specifically required for accurately orienting to shelter during escape. Shelter direction is encoded in RSP and SC neurons in egocentric coordinates and SC shelter-direction tuning depends on RSP activity. Inactivation of the RSP-SC pathway disrupts the orientation to shelter and causes escapes away from the optimal shelter-directed route, but does not lead to generic deficits in orientation or spatial navigation. We find that the RSP and SC are monosynaptically connected and form a feedforward lateral inhibition microcircuit that strongly drives the inhibitory collicular network because of higher RSP input convergence and synaptic integration efficiency in inhibitory SC neurons. This results in broad shelter-direction tuning in inhibitory SC neurons and sharply tuned excitatory SC neurons. These findings are recapitulated by a biologically constrained spiking network model in which RSP input to the local SC recurrent ring architecture generates a circular shelter-direction map. We propose that this RSP-SC circuit might be specialized for generating collicular representations of memorized spatial goals that are readily accessible to the motor system during escape, or more broadly, during navigation when the goal must be reached as fast as possible.

Spatial neglect encompasses impaired verticality representation after right hemisphere stroke.

Spatial neglect after right hemisphere stroke (RHS) was recently found to encompass lateropulsion, a deficit in body orientation with respect to gravity caused by altered brain processing of graviception. By analogy, we hypothesized that spatial neglect after RHS might encompass an altered representation of verticality. We also assumed a strong relation between body neglect and impaired postural vertical, both referring to the body. To tackle these issues, we performed contingency and correlation analyses between two domains of spatial neglect (body, extra-body) and two modalities of verticality perception (postural, visual) in 77 individuals (median age = 67) with a first-ever subacute RHS (1-3 months). All individuals with a transmodal (postural and visual) tilt in verticality perception (n = 26) had spatial neglect, but the reverse was not found. Correlation and multivariate analyses revealed that spatial neglect (and notably body neglect) was associated more with postural than visual vertical tilts. These findings indicate that after RHS, an impaired verticality representation results from a kind of graviceptive neglect, bearing first on somaesthetic graviception and second on vestibular graviception. They also suggest that the human brain uses not only a mosaic of 2D representations but also 3D maps involving a transmodal representation of verticality.

Evolution of innovation systems, economic growth, and sustainable competitiveness in Africa

This paper examines the systemic relationship between triple helix innovation systems and the gross domestic product per capita growth (GDPPC) in terms of sustainable competitiveness in Africa. To do this, the Generalized Moment Method on the panel vector autoregressive model is used to estimate helix models’ (triple helix, quadruple helix, quintuple helix, as well as the open quintuple helix, relative to external contributions) effects on GDPPC between 2007 and 2019 in 27 African countries, and causality tests completion as well. The results show 3 coevolution relationships resulting from the narrow innovation system, which is made up of the burden of government regulations, companies’ expenditures on research and development (R&D) as well as the quality of scientific research institutions. The system expansion (the broad innovation system) with the degree of consumer orientation and natural resource rents generate both 7 (respectively 3 and 4) coevolution relationships. Finally, the opening of the innovation system by considering the business impact of rules on foreign direct investment (BIFDI) alone, generates 5 coevolution relationships. So, in terms of overall sustainable competitiveness strategies in Africa, countries must focus on innovation system opening and natural resources exploitation to increase their GDPPC. Thus, this study fills the gap of a deficit in technological policy orientation on the relationships between innovation systems and sustainable competitiveness through economic growth in Africa.

Cognitive deficits for facial emotions among male adolescent delinquents with conduct disorder.

According to the social-cognitive theory and the social-information-processing theory, individuals with conduct disorder, a persistent and repetitive pattern of problematic behavior, might have cognitive biases toward hostile facial expressions. However, according to the optimal stimulation/arousal theory, the stimulation-seeking theory and the fearlessness theory, individuals with conduct disorder might have less fear and show less response to hostile or threatening facial expressions. To reconcile the discrepancy, we examined the cognitive biases including attentional processing and working memory processing to emotional faces among adolescents with conduct disorder. 35 male adolescent delinquents with conduct disorder and 35 age-matched delinquents without conduct disorder completed a visual search task and a delayed-match-to-sample task to examine their attentional processing and working memory processing for sad, angry, happy, and fearful faces, respectively. It was found that conduct disordered individuals searched angry and fearful faces, rather than sad and happy faces, more slowly than individuals without conduct disorder. However, no difference in mnemonic processing for facial emotions was found between groups. The results indicated that male adolescent delinquents with conduct disorder showed deficits in attentional orientation to hostile and threatening faces, supporting the optimal stimulation/arousal theory, the stimulation-seeking theory and the fearlessness theory, but not the social-cognitive theory.

Identifying ELF: an interdisciplinary perspective on social categories in lingua franca research

Abstract Researchers have a number of methodological tools and theoretical frameworks at their disposal when examining how English language identities are constructed in lingua franca encounters, including a conversation analytic understanding of an “emic social reality”; according to this perspective, a speaker’s identity falls within the interests of a researcher if, and only when, it is made relevant through social interaction. This paper builds on this tradition by studying how language identities can be understood from multiple analytic perspectives, including from an emic perspective. Drawing from a corpus of chat room data, the study examines how the social categories used by interactants to engage in identity work, such as categories that are inherently deficit in orientation (e.g., foreign language learner), may not precisely align with the preferred categories used in the lingua franca literature, such as categories that are more positive in nature (e.g., expert language user). These observations are used to explore some of the general methodological issues that exist when situating an analysis of identity within the study of lingua franca interactions.

Quality of life and cognitive assessment in healthy older Asian people with early and moderate chronic kidney disease: The NAHSIT 2013-2016 and validation study.

Taiwan has the highest prevalence of chronic kidney disease (CKD). Impaired cognition and quality of life are significant phenomena in the late stages of CKD. We sought to obtain an overview and the attributable effect of impaired glomerular filtration on multiple domains in cognition and dimensions of quality of life for community-based healthy older adults in Taiwan. The study was derived from the Nutrition and Health Survey in Taiwan (NAHSIT) 2013-2016, a nationwide cross-sectional study conducted to sample healthy, community-based older adults aged ≥65 years in Taiwan. Participants were categorized into four CKD groups: CKD stage 1, stage 2, stages 3a and 3b, and stages 4-5. The Mini-Mental State Examination (MMSE) and the QoL questionnaire derived from the 12-item Short Form Health Survey (SF-12) were measured. Generalized linear mixed models (GLMMs) and principal component regressions were employed for the analysis and validation, respectively. Participants with moderate CKD (stages 3a and 3b) showed deficits in global MMSE, domain orientation to time, calculation, complex commands, and role-physical and vitality in QoL questionnaires. In GLMMs, impaired eGFR per 30 mL/min/1.73 m² was associated with lower global MMSE scores (β = -0.807, standard error [SE] = 0.235, P = 0.0007), domain orientation to time (β = -0.155, SE = 0.047, P = 0.0011), calculation (β = -0.338, SE = 0.109, P = 0.0020), complex commands (β = -0.156, SE = 0.079, P = 0.0494), and role-physical (β = -2.219, SE = 0.779, P = 0.0046) dimensions of QoL. Elderly Han Chinese adults with moderately impaired renal filtration could manifest cognitive deficits in orientation to time, calculation, and impaired quality of life in physical role functioning.

Different strategies in pointing tasks and their impact on clinical bedside tests of spatial orientation

Deficits in spatial memory, orientation, and navigation are often early or neglected signs of degenerative and vestibular neurological disorders. A simple and reliable bedside test of these functions would be extremely relevant for diagnostic routine. Pointing at targets in the 3D environment is a basic well-trained common sensorimotor ability that provides a suitable measure. We here describe a smartphone-based pointing device using the built-in inertial sensors for analysis of pointing performance in azimuth and polar spatial coordinates. Interpretation of the vectors measured in this way is not trivial, since the individuals tested may use at least two different strategies: first, they may perform the task in an egocentric eye-based reference system by aligning the fingertip with the target retinotopically or second, by aligning the stretched arm and the index finger with the visual line of sight in allocentric world-based coordinates similar to using a rifle. The two strategies result in considerable differences of target coordinates. A pilot test with a further developed design of the device and an app for a standardized bedside utilization in five healthy volunteers revealed an overall mean deviation of less than 5° between the measured and the true coordinates. Future investigations of neurological patients comparing their performance before and after changes in body position (chair rotation) may allow differentiation of distinct orientational deficits in peripheral (vestibulopathy) or central (hippocampal or cortical) disorders.

Structural and functional brain alterations in patients with myasthenia gravis.

Myasthenia gravis is an autoimmune disease affecting neuromuscular transmission and causing skeletal muscle weakness. Additionally, systemic inflammation, cognitive deficits and autonomic dysfunction have been described. However, little is known about myasthenia gravis-related reorganization of the brain. In this study, we thus investigated the structural and functional brain changes in myasthenia gravis patients. Eleven myasthenia gravis patients (age: 70.64 ± 9.27; 11 males) were compared to age-, sex- and education-matched healthy controls (age: 70.18 ± 8.98; 11 males). Most of the patients (n = 10, 0.91%) received cholinesterase inhibitors. Structural brain changes were determined by applying voxel-based morphometry using high-resolution T1-weighted sequences. Functional brain changes were assessed with a neuropsychological test battery (including attention, memory and executive functions), a spatial orientation task and brain-derived neurotrophic factor blood levels. Myasthenia gravis patients showed significant grey matter volume reductions in the cingulate gyrus, in the inferior parietal lobe and in the fusiform gyrus. Furthermore, myasthenia gravis patients showed significantly lower performance in executive functions, working memory (Spatial Span, P = 0.034, d = 1.466), verbal episodic memory (P = 0.003, d = 1.468) and somatosensory-related spatial orientation (Triangle Completion Test, P = 0.003, d = 1.200). Additionally, serum brain-derived neurotrophic factor levels were significantly higher in myasthenia gravis patients (P = 0.001, d = 2.040). Our results indicate that myasthenia gravis is associated with structural and functional brain alterations. Especially the grey matter volume changes in the cingulate gyrus and the inferior parietal lobe could be associated with cognitive deficits in memory and executive functions. Furthermore, deficits in somatosensory-related spatial orientation could be associated with the lower volumes in the inferior parietal lobe. Future research is needed to replicate these findings independently in a larger sample and to investigate the underlying mechanisms in more detail.

Perspective taking and its structural correlates in early Alzheimer's disease

AbstractBackgroundThere is an increasing effort to find simple and reliable tests for the early diagnosis of Alzheimer´s disease (AD). Spatial orientation deficits are present early in AD and could thus serve as an early cognitive marker of the disease. We aimed to evaluate the potential of perspective taking tests to identify individuals with early AD and to determine associations between perspective taking and volumes of the selected brain regions affected in early AD.Method66 participants with amnestic mild cognitive impairment (aMCI) and positive AD‐biomarkers (aMCI due to AD, n=22), aMCI and negative biomarkers (aMCI AD‐negative, n=15), mild AD dementia (n=7) and cognitively normal (CN) older adults (n=22) underwent clinical and neuropsychological evaluation, MRI brain scan with automated volumetry, AD‐biomarker assessment and two perspective taking tasks: Standardized Road‐Map test of Direction Sense (RMTDS) and Perspective Taking/Spatial Orientation Test (PTSOT). In the RMTDS, the participants followed a pathway on a city map indicating a direction of turning at each intersection. The PTSOT included pictures of arrays of objects and participants indicated direction between selected objects.ResultThe aMCI due to AD and mild AD dementia groups had lower scores than the CN group (p&lt;0.05) in the PTSOT. The aMCI due to AD group had a lower score compared to the CN group (p&lt;0.05) in the RMTDS. There were no differences between the CN and aMCI AD‐negative groups in both tests. PTSOT scores correlated with volumes of the right inferior temporal gyrus and right and left precuneus.ConclusionThe perspective taking tests reliably detect spatial orientation impairment typical for early stages of AD. Worse performance in the PTSOT was associated with smaller volumes of the brain regions affected early in AD.

Disrupted Spatial Organization of Cued Exogenous Attention Persists Into Adulthood in Developmental Dyslexia.

Purpose: Abnormal exogenous attention orienting and diffused spatial distribution of attention have been associated with reading impairment in children with developmental dyslexia. However, studies in adults have failed to replicate such relationships. The goal of the present study was to address this issue by assessing exogenous visual attention and its peripheral spatial distribution in adults with developmental dyslexia.Methods: We measured response times, accuracy and eye movements of 18 dyslexics and 19 typical readers in a cued discrimination paradigm, in which stimuli were presented at different peripheral eccentricities.Results: Results showed that adults with developmental dyslexia were slower that controls in using their mechanisms of exogenous attention orienting. Moreover, we found that while controls became slower with the increase of eccentricity, dyslexics showed an abnormal inflection at 10° as well as similar response times at the most distant eccentricities. Finally, dyslexics show attentional facilitation deficits above 12° of eccentricity, suggesting an attentional engagement deficit at far periphery.Conclusion: Taken together, our findings indicate that, in dyslexia, the temporal deficits in orientation of attention and its abnormal peripheral spatial distribution are not restricted to childhood and persist into adulthood. Our results are, therefore, consistent with the hypothesis that the neural network underlying selective spatial attention is disrupted in dyslexia.

Cognitive aspects of attention disorders in Alzheimer's disease.

Attention deficits are encountered at a very early stage in the development of Alzheimer's disease. While these deficits may be detected using classic clinical tests or even through simple observation, experimental tools enable a more precise evaluation of these deficits, typically by differentiating between conditions in which the quantity of attention needed varies, and by recording response times, which allows for a more precise and modulated measurement. The sensitivity of these tools can be further increased by analysing the intra-individual variability of performance in these experiments, which is particularly significant during the earliest stages of the disease. We present the cognitive aspects of these deficits by regrouping them according to the type of experiment used to highlight each deficit. We therefore distinguish spatial attention orientation deficits, executive control deficits, and sustained attention deficits. In each section, we present some of the more commonly used experiments (spatial cueing, spatial search, dual tasks, conflict tasks, vigilance tests), and draw parallels between these experiments and everyday life.