A Frontal Neuropsychological Profile in Fitness to Drive.

Traffic accidents are a global concern due to the elevated mortality rates of both drivers and pedestrians. The World Health Organization declared 2011-2020 as the Decade of Action for Road Safety, endorsing initiatives to reduce traffic-related deaths. Yet, despite these incentives, fatal accidents still occur. Different studies have linked deficits in executive functions to risky driving attitudes and crashes. The present study focuses on demographic, cognitive and personality factors, related to the prefrontal cortex, that are characteristic of drivers prone to risky behavior behind the wheel. The penalty Points System was used to classify drivers as "safe", with no point loss over a two-year period, or "risky", with full point loss during the same interval. A neuropsychological assessment of prefrontal cognitive functions was carried out on each group to identify variables associated with safe and risky behavior. Neuropsychological indexes were obtained from a continuous performance task without cue (Simple Attention), a continuous performance task with cue (Conditioned Attention), the Tower of Hanoi test and the Neurologically-related Changes in Personality Inventory (NECHAPI). A Discriminant Analysis (DA) found that education level, reaction times in Simple and Conditioned Attention, learning errors in the Tower of Hanoi and vulnerability in the personality test, best predicted whether drivers were likely to be in the safe or risky group. Finally, a cross-validation analysis performed on the same sample correctly classified 87.5% of the drivers. These data suggest that prefrontal dysfunction contributes to risky behavior behind the wheel. The inclusion of cognitive programs to identify and train drivers with this propensity could reduce risky driving, and consequently, save lives on the road.

Modelo neurofuncional de la conciencia: bases neurofisiológicas y cognitivas / A neurofunctional model of consciousness: its neurophysiological and cognitive bases

El interés por la relación causal existente entre la conciencia y la actividad neuronal subyacente ha aumentado en las últimas décadas. Se han llevado a cabo numerosos estudios experimentales en modelos animales, en pacientes con daño cerebral y con neuroimagen funcional con una excelente precisión sobre las estructuras y redes cerebrales que subyacen a la conciencia. A pesar de la gran multitud de hallazgos, no existe una propuesta teórica que integre este conocimiento bajo un marco teórico coherente basado en las evidencias obtenidas. Las teorías existentes ofrecen una visión desmembrada de la conciencia, ya que plantean explicaciones causales que no incluyen una perspectiva funcional global sobre la interacción del conjunto de redes cerebrales involucradas en la conciencia. Este trabajo ofrece un marco teórico que integra el conocimiento empírico, generado en las últimas décadas, en un modelo neurofuncional de la conciencia. Este modelo representa la conciencia como un epifenómeno resultante de la activación secuencial de diferentes bucles neuronales que están formados por estructuras y redes cerebrales específicas retroalimentadas por sus propias operaciones para poder reconfigurar sus propios estados funcionales y todo el sistema. El sistema reticular activador ascendente, las redes talamocorticales y las redes corticocorticales sostienen procesos cognitivos diferenciados, aunque altamente dependientes y básicos para la experiencia final de conciencia. Todos estos sistemas forman un único espacio fisiológico en donde el individuo puede desplegar diferentes habilidades cognitivas que permiten la emergencia de conductas complejas como el lenguaje, el pensamiento y la cognición social

Interest in the causal relation between consciousness and the underlying neuronal activity has grown in recent decades. Numerous experimental studies have been carried out on the brain structures and networks underlying consciousness in animal models, in patients with brain damage and with very precise functional neuroimaging. In spite of the great multitude of findings, there is no theoretical proposal that integrates this knowledge under a coherent theoretical framework based on the evidence obtained. Existing theories offer a dismembered view of consciousness, since they pose causal explanations that do not include a global functional perspective of the interaction of the different brain networks involved in consciousness. This work offers a theoretical framework that integrates the empirical knowledge, generated in recent decades, into a neurofunctional model of consciousness. This model represents consciousness as an epiphenomenon resulting from the sequential activation of different neural loops that are formed by specific brain structures and networks which receive feedback from their own operations in order to reconfigure their own functional states and the entire system. The ascending reticular activating system, the thalamocortical networks and the cortico-cortical networks sustain cognitive processes that are differentiated, although highly dependent and fundamental for the final experience of consciousness. All these systems form a single physiological space where the individual can deploy different cognitive skills that allow the emergence of complex behaviours such as language, thought and social cognition

Prefrontal neural dynamics in consciousness.

The Prefrontal Cortex (PFC) is one of the principal brain regions studied in consciousness. Previous investigations suggest that the PFC is an important neural hub in both awareness and the manipulation of the content of consciousness. Despite a consensus in the scientific community regarding PFC function in cortico-cortical networks, there is still intense debate as to its role in the thalamocortical network and the formation of content of consciousness. The objective of this research is to provide a comprehensive review of the possible implications of PFC activity in awareness, with a focus on thalamic neural pathways that could explain perceptual alterations in the content of consciousness. We posit that the PFC and its connection with nonspecific thalamic nuclei could be responsible for the functional integration of sensory perception into a unique conscious content. This cortico-thalamocortical neural loop would denote a small closed-loop subnetwork within the thalamocortical system that organizes the flow of temporal and spatial information to maintain a subjective stream of consciousness. In particular, attentional top-down mechanisms between the PFC and the reticular thalamic nucleus could influence the formation of the content of consciousness through their capacity to regulate thalamic activity. Summarizing, the PFC acts as a dynamic and multifunctional neural hub that recalibrates global neural dynamics and regulates interactive brain processes associated with consciousness.

Safe driving and executive functions in healthy middle-aged drivers.

The introduction of the point system driver's license in several European countries could offer a valid framework for evaluating driving skills. This is the first study to use this framework to assess the functional integrity of executive functions in middle-aged drivers with full points, partial points or no points on their driver's license (N = 270). The purpose of this study is to find differences in executive functions that could be determinants in safe driving. Cognitive tests were used to assess attention processes, processing speed, planning, cognitive flexibility, and inhibitory control. Analyses for covariance (ANCOVAS) were used for group comparisons while adjusting for education level. The Bonferroni method was used for correcting for multiple comparisons. Overall, drivers with the full points on their license showed better scores than the other two groups. In particular, significant differences were found in reaction times on Simple and Conditioned Attention tasks (both p-values < 0.001) and in number of type-III errors on the Tower of Hanoi task (p = 0.026). Differences in reaction time on attention tasks could serve as neuropsychological markers for safe driving. Further analysis should be conducted in order to determine the behavioral impact of impaired executive functioning on driving ability.

Executive n-back tasks for the neuropsychological assessment of working memory.

Working memory (WM) has been defined as a cerebral function which allows us to maintain and manipulate information "online". One of the most widely used paradigms to assess WM is the n-back test. Despite its extensive application, some authors have questioned its capacity to assess the manipulation of WM load. The present study introduces a new version of the n-back test to carry out this assessment. We use functional near-infrared spectroscopy (fNIRS) to evaluate prefrontal cortex (PFC) activation. The modified n-back requires monitoring of sequentially presented stimuli (in this case the days of the week). The target response relates to a stimulus which appears previously, from 0 to 2 items back, on the computer screen. Our data reveals that while modified and unmodified n-back activate the same regions of the left PFC, our modified 2-back version shows significantly higher activation in the left dorsolateral PFC (DLPFC) and the left frontal opercula. These results suggest that increased complexity in verbal WM tasks entail greater executive control, which would lead to an increase in cerebral blood flow to the areas associated with verbal WM. Therefore, an increase in the manipulation of WM load in verbal tasks reflects greater physiological activity in the left DLPFC and the left frontal opercula. The modified n-back test may also be incorporated into the armamentarium of valid instruments for the neuropsychological assessment of the maintenance and manipulation of verbal information in tasks requiring working memory.

Reaction Time and Attention: Toward a New Standard in the Assessment of ADHD? A Pilot Study.

UNLABELLED: This pilot study shows results of an experiment comparing reaction times (RTs) and attentional performance between an ADHD group of 30 children and 30 controls, both Spanish speaking. The experiment was carried out using the Seville computerized neuropsychological battery (SNB). OBJECTIVE: This study had two goals: One was to test sensitivity of SNB for attention deficits in ADHD and the second was to detect differences in RTs between ADHD and controls. Possible explanations and implications of such differences are also discussed. METHOD: SNB computerized system was used to assess RTs and accuracy, and alternate forms of continuous performance task were used. RESULTS: Results showed high sensitivity of some of the SNB tests, especially cancellation tests. RTs were significantly different between groups. CONCLUSION: SNB represents a helpful tool for detection of attention deficits, and RT indices represent the most significant variable in differentiation of both groups studied.

Predictores de la recuperación funcional cognitiva en pacientes con traumatismo craneoencefálico / Predictors of the recovery of cognitive functions in patients with traumatic brain injury

Introducción. Tras un traumatismo craneoencefálico (TCE), el funcionamiento cognitivo de los pacientes puede resultar gravemente alterado. Diversos estudios han tratado de identificar las variables que mejor predicen su recuperación. Objetivos. Evaluar la recuperación funcional cognitiva de pacientes con TCE tras un programa de neurorrehabilitación e identificar las variables predictoras de dicha recuperación. Pacientes y métodos. Estudio pre-post retrospectivo de 58 pacientes adultos con TCE que realizaron un programa de rehabilitación intensivo. Todos fueron evaluados mediante la subescala de funcionalidad cognitiva de la medida de la independencia funcional + medida de la evaluación de la funcionalidad (FIM+FAM), al inicio y al final de la rehabilitación. Ambas puntuaciones fueron comparadas mediante la prueba no paramétrica de Wilcoxon. Se calculó el porcentaje de ganancia funcional cognitiva y se correlacionó con todas las variables recogidas. A partir de toda la información clínica, demográfica y cognitiva recogida, realizamos un análisis de regresión lineal múltiple para identificar los mejores predictores de dicha ganancia. Resultados. La funcionalidad cognitiva aumentó significativamente del 33,6% al 85% (p < 0,01). Los pacientes con mayor porcentaje de ganancia funcional cognitiva fueron aquellos con menor edad y período post-TCE, y mayores puntuaciones en la subescala cognitiva de la FIM+FAM y en las pruebas de atención condicional y curva de aprendizaje de Luria. Los mejores predictores de la recuperación funcional fueron el período post-TCE y la funcionalidad cognitiva al inicio (R2 ajustado = 55,8%). Conclusiones. El comienzo temprano de la rehabilitación y la mayor funcionalidad cognitiva al inicio resultaron ser los mejores predictores de la recuperación funcional cognitiva. Otras variables, como la edad o puntuaciones en pruebas cognitivas, también deben considerarse en futuros estudios (AU)

Introducción. After a traumatic brain injury (TBI), cognitive functionality may be severely altered. Some studies have aimed at identifying the best predictive variables for cognitive recovery, however, results still remain unclear. Aims: To assess the recovery of cognitive functionality in TBI patients after a rehabilitation programme, and to identify the variables that best predict the cognitive recovery. Patients and Methods: We conducted a retrospective pre-post study with 58 adult TBI patients that underwent an intensive rehabilitation programme. All of them were assessed using the cognitive functions sub-scale from the FIM+FAM scale, at admission and discharge. Both scores were compared using non-parametric test Wilcoxon. Cognitive functionality gain percentage was calculated and correlated with all the collected data. A multiple linear regression analysis was carried out to identify the best predictors of cognitive functionality gain percentage by introducing all clinical, demographic and cognitive information. Results. The group's cognitive functionality increased significantly from 33,6% to 85% (p < 0,01). Patients with higher cognitive functionality gain percentage were those with younger age, shorter time post-TBI, and higher scores on cognitive functions sub-scale, conditional attention and Luria's memory word tests. The best predictors for cognitive functionality gain percentage were time post-TBI and cognitive functions at admission (adjusted R2 = 55,8%). Conclusions:. Patients who started rehabilitation sooner and had a higher cognitive functionality at admission, showed the greatest increase in cognitive functionality gain percentage. Other variables like age, or scores on cognitive tests must also be considered in future studies (AU)

Molecular concentration of deoxyHb in human prefrontal cortex predicts the emergence and suppression of consciousness.

This is the first study to use fNIRS to explore anaesthetic depth and awakening during surgery with general anaesthesia. A 16 channel continuous wave (CW) functional near-infrared system (fNIRS) was used to monitor PFC activity. These outcomes were compared to BIS measures. The results indicate that deoxyHb concentration in the PFC varies during the suppression and emergence of consciousness. During suppression, deoxyHb levels increase, signalling the deactivation of the PFC, while during emergence, deoxyHb concentration drops, initiating PFC activation and the recovery of consciousness. Furthermore, BIS and deoxyHb concentrations in the PFC display a high negative correlation throughout the different anaesthetic phases. These findings suggest that deoxyHb could be a reliable marker for monitoring anaesthetic depth, and that the PFC intervenes in the suppression and emergence of consciousness.

Restoring cortical connectivity directionality and synchronization is essential to treating disorder of consciousness.

The design of neurorehabilitation therapy to treat subjects with altered consciousness provides opportunities and challenges to professionals involved with the care for these severely ill patients. While there is an increased interest in determining methods to restore consciousness in these patients, the process is complex and challenging, due in part to the diverse aetiology of these states of consciousness, and also to the intricate cerebral connectivity involved in their treatment. The present case study examines a patient who showed signs of emergence from the vegetative state after neurorehabilitation using The Combined Method Therapy (CMT). In this case, neurorehabilitation therapy was applied simultaneously with pharmacological treatment, stimulation, and neuroimaging techniques to help adjust drug dosage. The results of this study suggest that this combined approach to treatment promoted connectivity among posterior and anterior cortical regions aiding emergence from the vegetative state.

The sooner patients begin neurorehabilitation, the better their functional outcome.

PRIMARY OBJECTIVE: To determine whether early neurorehabilitation improves a patient's functional recovery. RESEARCH DESIGN: A retrospective study was carried out on patients with severe traumatic brain injury (TBI) who underwent a minimum of 4 months of integral and multidisciplinary neurorehabilitation. METHODS AND PROCEDURES: Fifty-eight patients with severe TBI were assessed at admission and at discharge using the FIM + FAM scale. Two groups were formed based on time elapsed from brain injury to onset of rehabilitation. The early treatment group (ET) included patients who began rehabilitation within the first 9 months post-trauma; the late treatment group (LT) began after the 9-month cut-off date. Intra- and between-group analysis of FIM + FAM scores were carried out at admission and discharge. Multiple linear regression was used to determine the best predictors for functional rehabilitation. MAIN OUTCOMES AND RESULTS: After neurorehabilitation, all subjects showed significant improvement in cognitive, motor, communication and psychosocial functioning. Moreover, the ET group showed better global functional outcome at discharge than patients who began later treatment. The best predictors for functional neurorehabilitation were months since injury, age, GCS score and months of treatment. CONCLUSIONS: It is concluded that the sooner patients begin neurorehabilitation, the better their functional outcome.

A chronometric functional sub-network in the thalamo-cortical system regulates the flow of neural information necessary for conscious cognitive processes.

The thalamo-cortical system has been defined as a neural network associated with consciousness. While there seems to be wide agreement that the thalamo-cortical system directly intervenes in vigilance and arousal, a divergence of opinion persists regarding its intervention in the control of other cognitive processes necessary for consciousness. In the present manuscript, we provide a review of recent scientific findings on the thalamo-cortical system and its role in the control and regulation of the flow of neural information necessary for conscious cognitive processes. We suggest that the axis formed by the medial prefrontal cortex and different thalamic nuclei (reticular nucleus, intralaminar nucleus, and midline nucleus), represents a core component for consciousness. This axis regulates different cerebral structures which allow basic cognitive processes like attention, arousal and memory to emerge. In order to produce a synchronized coherent response, neural communication between cerebral structures must have exact timing (chronometry). Thus, a chronometric functional sub-network within the thalamo-cortical system keeps us in an optimal and continuous functional state, allowing high-order cognitive processes, essential to awareness and qualia, to take place.

Recovery of cognitive function during comprehensive rehabilitation after severe traumatic brain injury.

OBJECTIVE: To explore the course and timing of functional recovery in patients who have emerged from coma after undergoing severe traumatic brain injury. METHODS: An observational study involving 19 patients with traumatic brain injury recovered from coma who underwent holistic, intensive and multidisciplinary neurorehabilitation. Daily performance in each cognitive function (long-term memory, short-term memory, orientation, calculation, attention, mental control, automation, and planning) was clinically scored and compared at admission and discharge. RESULTS: The course of cognitive recovery after post-traumatic coma is not uniform, offering a curve with many ups, downs and plateaus. To achieve a good response and outcome nearing normalcy, a patient needs over 300 h of intensive rehabilitation. CONCLUSION: The consolidation of functional recovery in patients with traumatic brain injury requires time and adequate training, and discharge is not recommended until cognitive improvement is established.

Synchronization between the anterior and posterior cortex determines consciousness level in patients with traumatic brain injury (TBI).

Survivors of traumatic brain injury (TBI) often suffer disorders of consciousness as a result of a breakdown in cortical connectivity. However, little is known about the neural discharges and cortical areas working in synchrony to generate consciousness in these patients. In this study, we analyzed cortical connectivity in patients with severe neurocognitive disorder (SND) and in the minimally conscious state (MCS). We found two synchronized networks subserving consciousness; one retrolandic (cognitive network) and the other frontal (executive control network). The synchrony between these networks is severely disrupted in patients in the MCS as compared to those with better levels of consciousness and a preserved state of alertness (SND). The executive control network could facilitate the synchronization and coherence of large populations of distant cortical neurons using high frequency oscillations on a precise temporal scale. Consciousness is altered or disappears after losing synchrony and coherence. We suggest that the synchrony between anterior and retrolandic regions is essential to awareness, and that a functioning frontal lobe is a surrogate marker for preserved consciousness. This article is part of a Special Issue entitled: Brain Integration.

Unresponsive wakefulness syndrome: a new name for the vegetative state or apallic syndrome.

BACKGROUND: Some patients awaken from coma (that is, open the eyes) but remain unresponsive (that is, only showing reflex movements without response to command). This syndrome has been coined vegetative state. We here present a new name for this challenging neurological condition: unresponsive wakefulness syndrome (abbreviated UWS). DISCUSSION: Many clinicians feel uncomfortable when referring to patients as vegetative. Indeed, to most of the lay public and media vegetative state has a pejorative connotation and seems inappropriately to refer to these patients as being vegetable-like. Some political and religious groups have hence felt the need to emphasize these vulnerable patients' rights as human beings. Moreover, since its first description over 35 years ago, an increasing number of functional neuroimaging and cognitive evoked potential studies have shown that physicians should be cautious to make strong claims about awareness in some patients without behavioral responses to command. Given these concerns regarding the negative associations intrinsic to the term vegetative state as well as the diagnostic errors and their potential effect on the treatment and care for these patients (who sometimes never recover behavioral signs of consciousness but often recover to what was recently coined a minimally conscious state) we here propose to replace the name. CONCLUSION: Since after 35 years the medical community has been unsuccessful in changing the pejorative image associated with the words vegetative state, we think it would be better to change the term itself. We here offer physicians the possibility to refer to this condition as unresponsive wakefulness syndrome or UWS. As this neutral descriptive term indicates, it refers to patients showing a number of clinical signs (hence syndrome) of unresponsiveness (that is, without response to commands) in the presence of wakefulness (that is, eye opening).

The Infrascanner, a handheld device for screening in situ for the presence of brain haematomas.

PURPOSE: Early identification and treatment of intracranial haematomas in patients sustaining traumatic brain injury is fundamental to successful treatment. This pilot study evaluates the Infrascanner as a handheld medical screening tool for detection, in situ, of brain haematomas in patients with head injury. METHODS: This study included 35 TBI patients aged 17-76 (M = 47.6), admitted to the neurosurgical intensive care unit and observation unit of a University Hospital in a Level 1 trauma centre. The Infrascanner NIRS device uses near infrared light measurements to calculate optical density in brain regions. RESULTS: Results show Infrascanner sensitivity at 89.5% and specificity at 81.2%. PPV was 85% and NPV 86.7%. The device detected 90% of extra-axial, 88.9% of intra-axial and 93.3% of non-surgical haematomas (less than 25 mL). PPV for this classification was 82.3%; 87.5% sensitivity was found when the Infrascanner exam was performed within 12 hours post-trauma, whereas after 12 hours post-trauma, exams had 90.1% sensitivity. CONCLUSIONS: This study demonstrates that the Infrascanner is useful in initial examinations and screenings of patients with head injury as an adjunct to a CT scan or when it is not available and may allow earlier treatment and reduce secondary injury caused by present and delayed haematomas.

Evidence of cognitive and neurophysiological impairment in patients with untreated naive acromegaly.

CONTEXT: Recent studies have suggested that long-term exposure to high levels of GH and IGF-I affect brain and cognitive functions. However, very few human studies have challenged this hypothesis. OBJECTIVE: The aim of this study is to explore whether GH/IGF-I excess in naive patients with acromegaly alters cognitive functions, particularly memory, and whether these alterations are accompanied by neurophysiological correlates. DESIGN: We conducted a comprehensive neuropsychological and neurophysiological exam on 16 naive acromegaly patients and 16 strictly matched healthy controls. Comparative analyses were carried out on major neurocognitive domains (executive functions, visual/verbal memory, attention, visuoconstructive abilities, and verbal fluency) and on quantitative electroencephalogram and low-resolution brain electromagnetic tomography sources. Results were correlated with GH and IGF-I hormone concentrations. RESULTS: Short- and long-term memory were the most severely impaired cognitive functions. Moreover, memory performance correlated negatively with GH and IGF-I concentrations. No association was detected between depression and memory impairment, and only a marginal association was found with quality of life. Finally, acromegaly patients showed power attenuation in fast frequency electroencephalogram bands, as well as decreased activity in prefrontal and middle temporal cortices, that was associated to cognitive performance. CONCLUSIONS: Results provide evidence of cognitive and neurophysiological impairment, characterized by moderate-to-severe memory impairment and decreased neural activity in specific brain areas. High levels of GH and IGF-I in acromegaly patients could be the basis for these findings.

The prognostic value of the temporal course of S100beta protein in post-acute severe brain injury: A prospective and observational study.

PRIMARY OBJECTIVE: To study the predictive capacity of early S100beta samples for long-term outcome prediction after severe TBI. METHODS AND PROCEDURES: Eighty-seven patients with severe TBI were studied. Clinical and CT scan were taken at admission. S100beta concentration was quantified at admission and 24, 48 and 72 hours post-TBI (days 0, 1, 2 and 3). Outcome was assessed 12 months after discharge using Glasgow Outcome Score (GOS). RESULTS: Significant negative correlations were found between 1-year GOS and S100beta concentrations on days 1-3, but not on day 0. Deceased patients showed higher S100beta concentration than survivors on days 1-3. Good (GOS = 4-5) vs poor outcome (GOS = 1-3) differed significantly on day 3. Death outcome was independently predicted by day 2 (>2.37 microg l(-1)), day 3 (>1.41 microg l(-1)) samples and absence of pupillary reaction. Poor outcome was predicted independently only by pupillary reaction and the 72-hour sample (>1.1 microg l(-1)), but this predictive model was less satisfactory than the predictive model for death. CONCLUSIONS: A temporal profile of S100beta release from admission to 72 hours post-TBI is strongly recommended for use in identifying patients at risk of developing a worse outcome. The S100beta protein might be an early biomarker for predicting long-term outcome in patients with acute severe TBI.

Information communication networks in severe traumatic brain injury.

In this study we explored the use of coherence and Granger causality (GC) to separate patients in minimally conscious state (MCS) from patients with severe neurocognitive disorders (SND) that show signs of awareness. We studied 16 patients, 7 MCS and 9 SND with age between 18 and 49 years. Three minutes of ongoing electroencephalographic (EEG) activity was obtained at rest from 19 standard scalp locations, while subjects were alert but kept their eyes closed. GC was formulated in terms of linear autoregressive models that predict the evolution of several EEG time series, each representing the activity of one channel. The entire network of causally connected brain areas can be summarized as a graph of incompletely connected nodes. The 19 channels were grouped into five gross anatomical regions, frontal, left and right temporal, central, and parieto-occipital, while data analysis was performed separately in each of the five classical EEG frequency bands, namely delta, theta, alpha, beta, and gamma. Our results showed that the SND group consistently formed a larger number of connections compared to the MCS group in all frequency bands. Additionally, the number of connections in the delta band (0.1-4 Hz) between the left temporal and parieto-occipital areas was significantly different (P < 0.1%) in the two groups. Furthermore, in the beta band (12-18 Hz), the input to the frontal areas from all other cortical areas was also significantly different (P < 0.1%) in the two groups. Finally, classification of the subjects into distinct groups using as features the number of connections within and between regions in all frequency bands resulted in 100% classification accuracy of all subjects. The results of this study suggest that analysis of brain connectivity networks based on GC can be a highly accurate approach for classifying subjects affected by severe traumatic brain injury.

Theory of mind deficits in patients with acquired brain injury: a quantitative review.

Impaired theory of mind (ToM) reasoning is considered an underlying cause of social cognition deficits in patients with acquired brain injury (ABI). However, the literature does not agree on the severity of ToM impairment in this clinical population, nor does it coincide on the proper tools for its assessment. In this paper, we use a meta-analytic approach to review 26 studies which compare the performance of ABI patients and healthy controls in four widely-used ToM tasks: first-order belief task, second order belief task, understanding indirect speech (IS) and social faux pas. Overall, patients show moderate to severe ToM impairment. The latter appears in faux pas (effect size=0.70) and understanding IS tasks (ES=0.87), while moderate impairment can be seen in second-order (ES=0.60) and first-order belief tasks (ES=0.52). The severity of ToM impairment was influenced by ratio of patients with frontal lobe lesion, ratio of patients with right hemisphere injury, type of belief task, and heterogeneity of the sample's etiology. Our results provide important quantitative evidence on the severity of ToM deficits in the ABI population, while identifying variables that influence these deficits. Implications for basic and clinical neuropsychology are discussed.