Attention and its disorders

The altered functional modular organization in systemic lupus erythematosus: an independent component analysis study

The aim of this study was to investigate the abnormities in functional connectivity (FC) within each modular network and between modular networks in patients with systemic lupus erythematosus (SLE). Twelve meaningful modular networks were identified via independent component analysis from 41 patients and 40 volunteers. Parametric tests were used to compare the intra- and intermodular FC between the groups. Partial correlation analysis was used to seek the relationships between abnormal FCs and the clinical data. Compared to the controls, SLE patients showed decreased intramodular FC in the anterior default mode network (aDMN), posterior default mode network (pDMN), ventral attention network (VAN), and sensorimotor network (SMN) and increased intramodular FC in the medial visual network (mVN) and left frontoparietal network. In addition, SLE patients showed decreased intermodular FC between the SMN and the lateral visual network (lVN), between the SMN and the VAN, and between the pDMN and the lVN and exhibited increased intermodular FC between the SMN and the salience network (SAN), between the pDMN and the SAN, and between the aDMN and the VAN. Moreover, we found several correlations among the abnormal FCs and the Mini-Mental State Examination in SLE patients. Mild cognitive impairment is compensated by the hyperconnectivity between the aDMN and the VAN, while severe cognitive impairment tends to be compensated by the hyperconnectivity between the SMN and the SAN. The FC value between the SMN and the SAN and between the aDMN and the VAN may serve as neuroimaging markers for monitoring cognitive progression in SLE patients.

Pretreatment intranetwork connectivity can predict the outcomes in idiopathic tinnitus patients treated with sound therapy

Previous studies demonstrated that brain morphological differences and distinct patterns of neural activation exist in tinnitus patients with different prognoses after sound therapy. This study aimed to explore possible differences in intrinsic network‐level functional connectivity (FC) in patients with different outcomes after sound therapy (narrow band noise). We examined intrinsic FC using resting‐state functional magnetic resonance imaging in 78 idiopathic tinnitus patients (including 35 effectively treated and 43 ineffectively treated) and 52 healthy controls (HCs) via independent component analysis. We also investigated the associations between the differences in FC and clinical variables. Analyses revealed significantly altered intranetwork connectivity in the auditory network (AUN) and some nonauditory‐related networks in the EG/IG patients compared to HCs; compared with EG patients, IG patients showed decreased intranetwork connectivity in the anterior default mode network (aDMN) and AUN. Meanwhile, robust differences were also evident in internetwork connectivity between some nonauditory‐related networks (salience network and executive control network; posterior default mode network and dorsal attention network) in the EG relative to IG patients. We combined intranetwork connectivity in the aDMN and AUN as an imaging indicator to evaluate patient outcomes and screen patients before treatment; this approach reached a sensitivity of 94.3% and a specificity of 76.7%. Our study suggests that tinnitus patients with different outcomes show distinct network‐level functional reorganization patterns. Intranetwork connectivity in the aDMN and AUN may be indicators that can be used to predict prognoses in patients with idiopathic tinnitus and screen patients before sound therapy.

Brain Structural and Functional Reorganization in Tinnitus Patients Without Hearing Loss After Sound Therapy: A Preliminary Longitudinal Study

Sound therapy is one of the most common first-line treatments for idiopathic tinnitus. We aimed to investigate the brain structural and functional alterations between patients with idiopathic tinnitus without hearing loss (HL) and healthy controls (HCs) and between patients before and after sound therapy (narrow band noise). Structural and resting-state functional images were acquired from 13 tinnitus patients without HL and 18 HCs before and after 6 months of narrow band sound therapy (only patients received the treatment). Voxel-based morphometry (VBM) and independent component analysis (ICA) were conducted to separately investigate the brain structural and functional changes. Associations between brain changes and clinical variables were also performed. After the treatment, the % improvement of THI score was −1.30% (± 63.40%). Compared with HCs, tinnitus patients showed gray matter and white matter atrophy in the left middle temporal gyrus at baseline, and the gray matter volume was further reduced after the treatment. The patients also showed increased white matter volume in the cingulum (cingulate), right calcarine, left rolandic operculum, and left parietal and frontal lobes. Additionally, compared with HCs, tinnitus patients exhibited positive [medial visual network (mVN) and sensorimotor network (SMN), mVN and auditory network (AN)] and negative [mVN and lateral visual network (lVN)] internetwork functional connectivity (FC) at baseline and negative [left frontoparietal network (LFPN) and dorsal attention network (DAN), AN and posterior default mode network (pDMN)] internetwork FC after the narrow band sound therapy. The patients also showed negative [LFPN and right frontoparietal network (RFPN), LFPN and RFPN, anterior default mode network (aDMN) and AN, aDMN and DAN] internetwork FC after the treatment when compared with baseline. Our findings suggest that although the outcomes of idiopathic tinnitus patients without HL were not very good when the improvement of THI scores was used as an evaluation indicator, the patients experienced significant differences in auditory-related and non-auditory-related brain reorganization before and after the narrow band sound therapy, that is, sound therapy may have a significant effect on brain reorganization in patients with idiopathic tinnitus. This study may provide some new useful information for the understanding of mechanisms underlying idiopathic tinnitus.

Cognitive Functions Predict Trajectories of Sleepiness Over 10 Years: A Population-Based Study

BACKGROUND

Excessive daytime sleepiness is associated with chronic disorders of aging and mortality. Because longitudinal data are limited on the development of sleep disturbances and cognitive changes in older adults, we investigated the demographic, clinical, and cognitive predictors of self-reported daytime sleepiness over a period of 10 years.

METHODS

We jointly modeled latent trajectories over time of sleepiness, cognitive domains, and informative attrition and then fit models to identify cognitive trajectories and baseline characteristics that predicted the trajectories of sleepiness.

RESULTS

Three latent trajectory groups were identified: emerging sleepiness, persistent sleepiness, and consistently low daytime sleepiness accounting for attrition in all groups. Compared with low sleepiness, emerging sleepiness was significantly associated with declining attention and subjective memory complaints; persistent sleepiness was associated with lower baseline scores in all cognitive domains, declining language trajectory, and more subjective memory complaints.

CONCLUSIONS

These findings suggest that persistent sleepiness and emerging daytime sleepiness are associated with cognitive decline and multiple morbidities, albeit more subtly in emerging daytime sleepiness. Furthermore, these data suggest that change in the cognitive domain of attention and subjective memory complaints may be early indicators of future sleep disturbance.

Pay attention to the basal ganglia: a volumetric study in early dementia with Lewy bodies

BACKGROUND

Cortical and subcortical cognitive impairments are usually found in dementia with Lewy bodies (DLB). Roughly, they comprise visuo-constructive/executive function and attention/processing speed impairments, whereas memory would remain relatively spared. In this study, we focused on the neuro-anatomical substrates of attention and processing speed, which is still poorly understood. For the purpose of the study, we examined the correlations between behavioral scores measuring the speed of processing and the degree of cerebral atrophy in patients with prodromal to moderate DLB.

METHODS

Ninety-three prodromal to moderate DLB patients (mean MMSE = 25.5) were selected to participate in the study as well as 28 healthy elderly subjects (mean MMSE = 28.9), matched in terms of age and educational level. The Trail Making Test A (TMTA) and the Digit Symbol Substitution Test (DSST) were used to assess attention and processing speed. Behavioral performances were compared between patients and healthy control subjects. Three-dimensional MRI images were acquired for all participants, and correlational analyses were performed in the patient group using voxel-based morphometry (VBM).

RESULTS

The behavioral results on both the TMTA (p = .026) and the DSST (p < .001) showed significantly impaired performances in patients in comparison with control subjects. In addition, correlational analyses using VBM revealed for the TMTA negative correlations in the caudate nucleus (left cluster peak significant at .05 FWE corrected), the putamen, the left thalamus, and the subthalamic nuclei (p < .05 FDR corrected). Some positive correlations associated with the DSST were found in the right inferior frontal gyrus, the left thalamus, and the left cerebellum (p < .001 uncorrected).

CONCLUSIONS

The behavioral results are in line with the literature on the DLB cognitive profile and confirm the existence of attention and processing speed impairment. Interestingly, VBM analysis revealed the involvement of the basal ganglia, in particular, the left caudate nucleus, which is part of the attention cerebral network, suggesting an important role of this structure for attentional processing speed. This also suggests the clinical implication of damage in this region relatively early in the course of the disease.

Population-based genome-wide association study of cognitive decline in older adults free of dementia: identification of a novel locus for the attention domain

To identify novel loci that affect cognitive decline in older adults free of dementia, we conducted genome-wide and gene-based meta-analyses on longitudinal slopes of 5 cognitive domains (memory, executive function, language, attention/processing speed, and visuospatial ability) derived from 2 population-based cohorts. For decline over time in each cognitive domain, we normalized intraindividual slopes within each cohort, accounting for baseline age, sex, and years of education. Normalized slope for each domain was used in cohort-specific genome-wide analyses after including top principal components as covariates followed by genome-wide and gene-based meta-analyses. Both analyses revealed a novel WDFY2 locus at genome-wide (p = 3.37E-08) and gene-wide (p = 7.10E-07) significance levels for the attention/processing speed domain. In the GTEx eQTL analysis, genome-wide significant single-nucleotide polymorphism was associated with RNA expression levels of WDFY2 in several brain regions: cerebellar hemisphere (p = 1.07E-04), cerebellum (p = 6.92E-04), hippocampus (p = 2.18E-03) and cortex (p = 2.29E-02), and in whole blood (p = 4.41E-05). Our results suggest that WDFY2 genetic variation may affect individual differences in decline over time on tests of attention/processing speed.

Altered functional organization within and between resting-state networks in chronic subcortical infarction

This study aimed to investigate the changes in functional connectivity (FC) within each resting-state network (RSN) and between RSNs in subcortical stroke patients who were well recovered in global motor function. Eleven meaningful RSNs were identified via functional magnetic resonance imaging data from 25 subcortical stroke patients and 22 normal controls using independent component analysis. Compared with normal controls, stroke patients exhibited increased intranetwork FC in the sensorimotor (SMN), visual (VN), auditory (AN), dorsal attention (DAN), and default mode (DMN) networks; they also exhibited decreased intranetwork FC in the frontoparietal network (FPN) and anterior DMN. Stroke patients displayed a shift from no FC in controls to negative internetwork FC between the VN and AN as well as between the VN and SMN. Stroke patients also exhibited weakened positive (anterior and posterior DMN; posterior DMN and right FPN) or negative (AN and right FPN; posterior DMN and dorsal SMN) internetwork FC when compared with normal controls. We suggest that subcortical stroke may induce connectivity changes in multiple functional networks, affecting not only the intranetwork FC within RSNs but also the internetwork FC between these RSNs.

Saliency mapping in the optic tectum and its relationship to habituation

Habituation of the orienting response has long served as a model system for studying fundamental psychological phenomena such as learning, attention, decisions, and surprise. In this article, we review an emerging hypothesis that the evolutionary role of the superior colliculus (SC) in mammals or its homolog in birds, the optic tectum (OT), is to select the most salient target and send this information to the appropriate brain regions to control the body and brain orienting responses. Recent studies have begun to reveal mechanisms of how saliency is computed in the OT/SC, demonstrating a striking similarity between mammals and birds. The saliency of a target can be determined by how different it is from the surrounding objects, by how different it is from its history (that is habituation) and by how relevant it is for the task at hand. Here, we will first review evidence, mostly from primates and barn owls, that all three types of saliency computations are linked in the OT/SC. We will then focus more on neural adaptation in the OT and its possible link to temporal saliency and habituation.

Executive functioning in schizophrenia

The executive function (EF) is a set of abilities, which allows us to invoke voluntary control of our behavioral responses. These functions enable human beings to develop and carry out plans, make up analogies, obey social rules, solve problems, adapt to unexpected circumstances, do many tasks simultaneously, and locate episodes in time and place. EF includes divided attention and sustained attention, working memory (WM), set-shifting, flexibility, planning, and the regulation of goal directed behavior and can be defined as a brain function underlying the human faculty to act or think not only in reaction to external events but also in relation with internal goals and states. EF is mostly associated with dorsolateral prefrontal cortex (PFC). Besides EF, PFC is involved in self-regulation of behavior, i.e., the ability to regulate behavior according to internal goals and constraints, particularly in less structured situations. Self-regulation of behavior is subtended by ventral medial/orbital PFC. Impairment of EF is one of the most commonly observed deficits in schizophrenia through the various disease stages. Impairment in tasks measuring conceptualization, planning, cognitive flexibility, verbal fluency, ability to solve complex problems, and WM occur in schizophrenia. Disorders detected by executive tests are consistent with evidence from functional neuroimaging, which have shown PFC dysfunction in patients while performing these kinds of tasks. Schizophrenics also exhibit deficit in odor identifying, decision-making, and self-regulation of behavior suggesting dysfunction of the orbital PFC. However, impairment in executive tests is explained by dysfunction of prefronto-striato-thalamic, prefronto-parietal, and prefronto-temporal neural networks mainly. Disorders in EFs may be considered central facts with respect to schizophrenia and it has been suggested that negative symptoms may be explained by that executive dysfunction.

Executive attention impairment in first-episode schizophrenia

BACKGROUND

We compared the attention abilities of a group of first-episode schizophrenia (FES) patients and a group of healthy participants using the Attention Network Test (ANT), a standard procedure that estimates the functional state of three neural networks controlling the efficiency of three different attentional behaviors, i.e., alerting (achieving and maintaining a state of high sensitivity to incoming stimuli), orienting (ability to select information from sensory input), and executive attention (mechanisms for resolving conflict among thoughts, feelings, and actions).

METHODS

We evaluated 22 FES patients from 17 to 29 years of age with a recent history of a single psychotic episode treated only with atypical neuroleptics, and 20 healthy persons matched with FES patients by sex, age, and educational level as the control group. Attention was estimated using the ANT in which participants indicate whether a central horizontal arrow is pointing to the left or the right. The central arrow may be preceded by spatial or temporal cues denoting where and when the arrow will appear, and may be flanked by other arrows (hereafter, flankers) pointing in the same or the opposite direction.

RESULTS

The efficiency of the alerting, orienting, and executive networks was estimated by measuring how reaction time was influenced by congruency between temporal, spatial, and flanker cues. We found that the control group only demonstrated significantly greater attention efficiency than FES patients in the executive attention network.

CONCLUSIONS

FES patients are impaired in executive attention but not in alerting or orienting attention, suggesting that executive attention deficit may be a primary impairment during the progression of the disease.

A Preliminary Standardisation of the Bohnen et al. Version of the Stroop Color-Word Test for Setswana-Speaking University Students

The objective of this study was to undertake a preliminary standardisation of the Bohnen, Jolles, and Twijnstra (1992) version of the Stroop Color-Word Test for Setswana-speaking university students. The Bohnen et al. (1992) version (Bohnen Stroop), which is a modified version of the original Stroop Color-Word Test, is traditionally considered a neuropsychological measure of selective attention, otherwise known as concentration. In the present study, a computerised version of the Bohnen Stroop was administered to 102 Setswana-speaking university subjects between the ages of 18 and 30 years. Tests for normality indicated that, except for Subtask III and Interference Measure III-II, the distributions were not normal. Mann-Whitney test analysis indicated that age and gender significantly affected test performance, specifically: (a) although the 22–30 year-old group was (significantly) slower than the 18–21 year-old one on Subtask I (i.e. word reading) and Subtask II (i.e. colour naming), this same (i.e. older) group was faster — and thereby displaying reduced interference — on Interference Measure III-II (i.e. standard interference); and (b) the female group performed faster on Subtask II (i.e., colour-naming). Preliminary normative data, including z-scores and cut-off scores, were established. Furthermore, Cronbach's alpha calculations for the subtasks and interference measures yielded values ranging from .78 (Subtask III) to .88 (Subtask IV), thereby demonstrating acceptable internal consistency. Ultimately, however, the normative data are based on non-normal distributions and, therefore, a complete standardisation of the Bohnen Stroop is recommended.

Dysfunction of the attentional brain network in children with Developmental Coordination Disorder: a fMRI study

Children with Developmental Coordination Disorder (DCD) present impaired motor skills, frequently associated with impaired attentional and executive functions. The objective of this study was to assess the impact of DCD on effective connectivity applied to a putative model of inhibition. fMRI was performed in 9 children with DCD and 10 control children (8-13 years old) performing a go-nogo task. As previously reported, children with DCD obtained a similar score for correct inhibitions as controls, but responses were slower and more variable than in controls. Compared to controls, Structural Equation Modeling indicated that: (1) path coefficients from both middle frontal cortex (MFC) and anterior cingulate cortex (ACC) to inferior parietal cortex (IPC) increased in children with DCD particularly in the left hemisphere; (2) path coefficients between striatum and parietal cortex decreased in children with DCD in the right hemisphere. Results suggest that DCD could be characterized by abnormal brain hemispheric specialization during development. Furthermore, connectivity in the MFC-ACC-IPC network could indicate that children with DCD are less able than healthy children to easily and/or promptly switch between go and nogo motor responses. However, children with DCD seem to compensate for this poor efficiency by more actively engaging the ACC to prevent commissions allowing maintenance of a good level of inhibition.

Cognitive function in the locked-in syndrome

OBJECTIVE

The lockedin syndrome (LIS) originates from a ventro-pontine lesion resulting in a complete quadraplegia and anarthria. Classically, communication remains possible by means of spared vertical eye movements and/or blinking. To allow assessing cognitive functions in LIS patients, we propose here a neuropsychological testing based on eye-coded communication.

METHODS

Ten chronic LIS survivors were assessed 1 to 6 years after their brain insult. One patient was evaluated subacutely (at 2 months) and retested at 6 and 16 months. Neuropsychological testing encompassed short- and long-term memory, attention, executive functioning, phonological and semantic processing and verbal intelligence.

RESULTS

None of the patients showed alterations in verbal intelligence. Impairments in one or several tests were found in five patients. In three of these patients, neuropsychological deficits could be related to additional cortical or thalamic structural brain lesions. In the other 2 patients, weakness or signs of fatigue only were observed in one or two cognitive tasks. Repeated measures in a subacute patient with pure brainstem lesion indicate the recovery of good levels of cognition 6 months after injury.

CONCLUSION

Results indicate that LIS patients can recover intact cognitive levels in cases of pure brainstem lesions, and that additional brain injuries are most likely responsible for associated cognitive deficits in the LIS. Furthermore, a systematic neuropsychological assessment in LIS patients would allow detecting their cognitive deficits,which will contribute to improve their quality of life and of communication with family and medical caretakers.

Neuropsychological study of underweight and "weight-recovered" anorexia nervosa compared with bulimia nervosa and normal controls

OBJECTIVE

To compare executive, memory and visuospatial functioning of DSM-IV anorexia nervosa (AN), bulimia nervosa (BN), and normal controls (NC).

METHOD

A comparison of women involving: (i) 16 AN with body mass indices (BMI) < or = 17.5 kg/m(2); (ii) 12 AN with BMI > 18.5 kg/m(2) for at least 3 months; (iii) 13 BN; and (iv) 16 NC participants was performed with groups of similar age and intelligence. Groups were assessed with EDE-12, MADRS, HAMA, Cognitive Drug Research (CDR) battery, and Bechara tasks.

RESULTS

Significant impairments in CDR Power of Attention were present in underweight AN and BN participants. CDR Morse Tapping was significantly impaired in all clinical groups. The BN and weight-recovered AN groups were significantly impaired on CDR immediate word recall. The BN group alone was significantly impaired on CDR delayed word recall.

CONCLUSION

Attentional impairment is similar in AN and BN. Impaired motor tasks in AN persist after "weight-recovery" and are similar to impairments in BN. BN may be discriminated from AN on word recall.

Nicotinic receptor mechanisms and cognition in normal states and neuropsychiatric disorders

Cigarette smoking rates in the American population are approximately 23%, whereas rates of smoking in clinical and population studies of individuals with neuropsychiatric disorders are typically two- to four-fold higher. Studies conducted in a variety of neuropsychiatric populations [e.g. attention-deficit hyperactivity disorder (ADHD), Alzheimer's disease, schizophrenia] have collectively suggested that nicotine may be efficacious in remediating selected cognitive deficits associated with these disorders, thus providing a framework for understanding the specific vulnerability of these patients to smoking initiation and maintenance. However, the specific gain in cognitive performance produced by nicotine administration in healthy subjects with normal cognitive function is less clear. This article reviews our current understanding of central nicotinic acetylcholine receptor (nAChRs) systems in normal and neuropsychiatric disease states and, specifically, their role with respect to cognitive dysfunction and clinical symptoms in several specific neuropsychiatric populations, including ADHD, Alzheimer's disease, Parkinson's disease, Tourette's Disorder, schizophrenia and affective disorders. The potential benefits of nicotinic agents for therapeutic use in neuropsychiatric disorders is discussed, as well as directions for further research in this area.

Nicotinic receptor mechanisms and cognition in normal states and neuropsychiatric disorders

Cigarette smoking rates in the American population are approximately 23%, whereas rates of smoking in clinical and population studies of individuals with neuropsychiatric disorders are typically two- to four-fold higher. Studies conducted in a variety of neuropsychiatric populations [e.g. attention-deficit hyperactivity disorder (ADHD), Alzheimer's disease, schizophrenia] have collectively suggested that nicotine may be efficacious in remediating selected cognitive deficits associated with these disorders, thus providing a framework for understanding the specific vulnerability of these patients to smoking initiation and maintenance. However, the specific gain in cognitive performance produced by nicotine administration in healthy subjects with normal cognitive function is less clear. This article reviews our current understanding of central nicotinic acetylcholine receptor (nAChRs) systems in normal and neuropsychiatric disease states and, specifically, their role with respect to cognitive dysfunction and clinical symptoms in several specific neuropsychiatric populations, including ADHD, Alzheimer's disease, Parkinson's disease, Tourette's Disorder, schizophrenia and affective disorders. The potential benefits of nicotinic agents for therapeutic use in neuropsychiatric disorders is discussed, as well as directions for further research in this area.