Recruitment strategies for studying dementia in later life among diverse cultural groups

This article provides conceptual and theoretical guidance on approaches to enhance recruiting and retaining diverse populations in dementia research by using a sociocultural perspective and constructivist approach. Informed by this conceptual and theoretical guidance, the article also discusses some of the major barriers to recruitment with ideas on how to address these barriers. Further discussion is provided on building community relations and capacity, and strategies to increase the level of participation in dementia care research. The article ends with best strategies for addressing barriers to recruitment and retention, building community relations and capacity, and increasing participation in research projects.     

Repetitive transcranial magnetic stimulation over the right dorsolateral prefrontal cortex disrupts digit span task performance

The digit span task measures the maintenance of information in short-term memory, and is one of the most widely used tests in clinical and experimental neuropsychology. Functional imaging studies have suggested a role of the right dorsolateral prefrontal cortex (DLPFC) in digit span performance. It remains unclear however, whether activation of this area is critical for task performance. Using repetitive transcranial magnetic stimulation (rTMS) over the right DLPFC in a sham-controlled design, we tested the hypothesis of the involvement of the right DLPFC in digit span task performance. We observed a significant disruption of digit span performance in healthy subjects in the real rTMS condition as compared to the sham condition. This effect of rTMS did not differ between digits forward and digits backward. Our results suggest that the right DLPFC is critical for central executive processes utilized by the digits forward and backward tasks.     

Acute effects of bromazepam on signal detection performance, digit symbol substitution test and smooth pursuit eye movements

Effects of 6 and 12 mg bromazepam on reaction time, stimulus sensitivity and response bias in a 1-hour visual attention task, on smooth pursuit eye movements, and on performance in the digit symbol substitution test (DSST) were investigated in 12 healthy male volunteers. It was a placebo-controlled, double-blind, crossover study that used repeated measures. Three saliva samples and a blood sample were taken for correlating drug concentration and performance. Bromazepam lowered stimulus sensitivity dose-dependently. Response times for hits and response bias were affected by the 12-mg dose only. DSST performance decreased dose-dependently. Smooth pursuit was equally impaired by 6 and 12 mg. Concentrations in serum correlated with concentrations in saliva, but serum and saliva concentrations did not correlate with task performance.     

Brain activation during a linguistic task in conduction aphasia

In order to investigate functional cortical reorganization during recovery from conduction aphasia, regional cerebral blood flows (rCBF) were measured by the two-dimensional 133 Xenon inhalation method in ten stroke patients. rCBF measurements were performed at rest and during the performance of a linguistic task, one month and three months after onset. The analysis of flow changes from rest to test condition indicates an increasing contribution of the right hemisphere as time goes on. The absence of flow increase in Broca's region suggests that this region is definitively disconnected from posterior language "centers" by the arcuate fasciculus lesion.     

Screening for cognitive impairment in multiple sclerosis using the Symbol digit Modalities Test

Cognitive impairment is common in multiple sclerosis (MS), yet difficult to detect during routine neurologic examination. Therefore, brief screening tests that identify patients who may benefit from a more thorough assessment or treatment are needed. We investigated the utility of the Symbol Digit Modalities Test (SDMT) as a screen for cognitive dysfunction because it can be administered and scored in about 5 minutes. One hundred MS patients and 50 healthy controls, matched on demographic variables, participated in the study. Examination procedures included the neuropsychological (NP) tests included in the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery. Patients were considered impaired if they performed one and a half standard deviations below controls on two or more MACFIMS variables, excluding the SDMT. Bayesian statistics showed that a total score of 55 or lower on the SDMT accurately categorized 72% of patients, yielding sensitivity of 0.82, specificity of 0.60, positive predictive value (PPV) of 0.71, and negative predictive value (NPV) of 0.73. These results suggest that the effectiveness of the SDMT as a screen for cognitive impairment in MS is roughly equal to that of other psychometric and questionnaire methods.     

Event-related brain potentials in reading disabled children during an inverse serial digit detection task.

It has been reported that limitations in different components of working memory could underlie reading disabilities. In addition, reading-disabled (RD) children seem to perform worse when digit name processing is required. With the purpose to explore further these assumptions one inverse serial digit detection task was evaluated using event-related brain potentials in fifteen 8-year-old RD children and a control group (CG). CG obtained significantly more correct responses than RD, but had similar reaction times. The experimental task performance significantly correlated with the performance on reading tests. Difference event-related potentials showed a voltage component peaking at 160 ms over frontocentral leads (P160d) that reached significantly higher amplitude in RD group, and was interpreted as an index of the amount of neural resources involved in visual working memory load. The amplitude of P160d significantly correlated with reading speed, the backward digit span and with the experimental task performance. Present results point out that highly demanding working memory tasks reveal behavioral and electrophysiological differences in RD children with respect to healthy controls.     

Symbol vs. Digit Substitution Task Performance In Diverse Cultural and Linguistic Groups

In spite of limited empirical data to guide their use, nonverbal neuropsychological measures are frequently utilized in the assessment of non-native English speakers in an effort to minimize cultural and linguistic factors that may influence performance. In this study, three groups of participants from different cultural and linguistic backgrounds were compared on two brief, nonverbal substitution tasks sensitive to cerebral dysfunction: WAIS-R Digit Symbol and the Symbol Digit Modalities Test. Within each group, participants exhibited a similar pattern of performance, earning higher scores on Digit Symbol. However, when dominant Spanish speakers were further subdivided into higher and lower education groups, less educated Spanish speakers achieved lower scores compared to all other groups on both tasks, and failed to show the performance advantage for Digit Symbol. In spite of differences in the respective countries of educational experience, the more highly educated dominant Spanish speakers performed as well as monolingual nonHispanic and Hispanic bilingual participants on both tasks. Years of formal education appears to be the most relevant variable in explaining performance differences across cultural and linguistic groups on these tasks.     

Information overload disrupts digit recall performance in schizophrenics

The effect of auditory information overload on schizophrenics was examined by using a modified forward digit recall task. When memory capacity was exceeded, schizophrenics, but not controls, showed severe disruptions in performance on individual trials. Theories to account for the disruptions are discussed. A combination of factors, rather than simply limited information handling capacity, appears best able to account for the phenomenon. It is emphasized that further understanding of active cognitive process requires examination of trial by trial individual subject data.     

Speed and memory in WAIS-R-NI Digit Symbol performance among healthy older adults.

Although roles have been proposed for both graphomotor speed and learning in the execution of Digit Symbol, few data have been available concerning performance across the adult lifespan on the Symbol Copy, paired associates, or free recall measures derived from Digit Symbol and recommended in the WAIS-R-NI. We report findings on 177 healthy older adults (ages 50-90), providing normative data by age group, education level, and gender. As previously reported, Digit Symbol scores decline steeply with age (r = -.64). Symbol Copy speed declines almost as steeply (r = -.58). Incidental learning, however, declines only modestly (r = -.26 on both measures). Symbol Copy is a far stronger correlate of Digit Symbol (r = .72) than are paired associates or free recall (r = .26 and r = .28, respectively). The 2 incidental learning measures do, however, offer valuable supplementary information as part of a comprehensive individual assessment. When low Digit Symbol scores are produced by slowing on Symbol Copy, further evaluation of perceptual and motor speed and dexterity are indicated. When low incidental learning scores are obtained, further evaluation of memory is warranted. Qualitative analysis of errors (e.g., rotations) made on the incidental learning procedures may also be valuable.     

Neuroimaging of the functional and structural networks underlying visuospatial vs. linguistic reasoning in high-functioning autism

High-functioning individuals with autism have been found to favor visuospatial processing in the face of typically poor language abilities. We aimed to examine the neurobiological basis of this difference using functional magnetic resonance imaging and diffusion tensor imaging. We compared 12 children with high functioning autism (HFA) to 12 age- and IQ-matched typically developing controls (CTRL) on a pictorial reasoning paradigm under three conditions: V, requiring visuospatial processing; S, requiring language (i.e., semantic) processing; and V+S, a hybrid condition in which language use could facilitate visuospatial transformations. Activated areas in the brain were chosen as endpoints for probabilistic diffusion tractography to examine tract integrity (FA) within the structural network underlying the activation patterns. The two groups showed similar networks, with linguistic processing activating inferior frontal, superior and middle temporal, ventral visual, and temporo-parietal areas, whereas visuospatial processing activated occipital and inferior parietal cortices. However, HFA appeared to activate occipito-parietal and ventral temporal areas, whereas CTRL relied more on frontal and temporal language regions. The increased reliance on visuospatial abilities in HFA was supported by intact connections between the inferior parietal and the ventral temporal ROIs. In contrast, the inferior frontal region showed reduced connectivity to ventral temporal and middle temporal areas in this group, reflecting impaired activation of frontal language areas in autism. The HFA group's engagement of posterior brain regions along with its weak connections to frontal language areas suggest support for a reliance on visual mediation in autism, even in tasks of higher cognition.     

首发精神分裂症患者倒背数字作业的fMEI研究

目的利用功能磁共振成像(fMRI)探讨首发精神分裂症患者倒背数字作业激发图像的特点.方法 36例符合ICD-10诊断标准的(首发)精神分裂症患者及18名健康志愿者进行以倒背数字作业(backward digit span task, BDST)作为刺激模式、采用组块(block)设计的fMRI检查,经工作站处理后获功能图像.用阳性和阴性症状量表(PANSS)评价精神分裂症患者精神症状的严重程度. 结果 (1)健康志愿者与精神分裂症患者激活脑区的范围均较广泛,健康志愿者的左侧额上回、双侧额中回、左侧额下回、左侧中央前回、左侧顶上小叶、左侧缘上回、左侧颞下回及左侧枕颞外侧回等脑区均有明显激活.两组激活的脑区在额叶、颞叶、顶叶、枕叶及扣带回的分布,以及各脑区内部分布的差异均没有显著性(P>0.05).(2)健康志愿者与精神分裂症患者激活计数左侧额上回分别为16和11,左侧额下回分别为15和12,左侧中央前回分别为16和17,左侧颞下回分别为14和12,左侧顶上小叶分别为14和14,左侧缘上回分别为14和7,左侧枕颞外侧回分别为14和7,右侧中央前回分别为13和7,右侧枕颞外侧回分别为11和8,两组上述部位激活计数的差异均有显著性(P均＜0.05).(3)健康志愿者与精神分裂症患者左侧额叶背外侧的激活平均体积分别为(362±296)个体素和(79±101)个体素,差异有非常显著性(P=0.001);右侧顶叶后下部的激活平均体积分别为(448±273)个体素和(193±236)个体素,差异有显著性(P=0.039). 结论早期精神分裂症患者可能存在工作记忆缺陷,包括激活信息的保持及执行控制过程,激活信息的保持缺陷可能与左侧额叶腹外侧及顶叶后下部的功能低下有关,而执行控制缺陷可能与左侧额叶背外侧的功能低下有关.     

Arousal and auditory vigilance in individuals with aphasia during a linguistic and nonlinguistic task

Background: Attentional deficits have been observed in individuals with aphasia. Attention, specifically vigilance, is believed to be related to arousal. However, our understanding of arousal and its impact on vigilance performance in individuals with aphasia is very limited. Aims: The purpose of the current study was to investigate whether there is nonoptimal arousal in individuals with aphasia that would affect auditory processing of linguistic and nonlinguistic stimuli. Additionally, this study explored whether there was generalised, nonoptimal arousal and impaired vigilance or deficits specific to linguistic processing. Methods & Procedures: A total of 20 males (10 with left‐hemisphere stroke and aphasia and 10 nonbrain‐damaged controls) participated in this study. Physiologic arousal indexed by cardiovascular and neuroendocrine measures and vigilance performance was compared between the two groups during linguistic and nonlinguistic vigilance tasks. Outcomes & Results: Results indicated that arousal levels and vigilance performance differed between the two groups. However, within groups arousal and vigilance did not differ between the linguistic and nonlinguistic tasks. Conclusions: The present findings suggest that individuals with aphasia have decreased overall vigilance and nonoptimal arousal regardless of the linguistic or nonlinguistic nature of the stimuli.     

Positive and negative symptoms of schizophrenia and linguistic performance

Selected subjects from a group of first onset schizophrenics (aged under 30 years) were taken from a previous study and placed in one of two groups depending upon whether they had exclusively positive symptoms (n = 9) or a mixture of positive and negative symptoms (n = 9). Their linguistic profiles were compared with those of a group of controls (n = 10) matched for educational attainment and parental social class. Both groups of schizophrenics had significantly lower integrity scores, suggesting that they made more syntactic and semantic errors. Those patients who presented with negative symptoms tended to have speech of lower syntactic complexity than the other two groups, although the difference just failed to reach statistical significance. It is suggested that syntactic and semantic errors are state dependent features associated with positive symptoms, whereas low syntactic complexity may be a more enduring feature associated with the presence of negative symptoms.     

Behavioural and neurophysiological correlates of dyslexia in the continuous performance task.

OBJECTIVE: To investigate whether attentional difficulties are a "core" feature of developmental Dyslexia. METHODS: Behavioural indices and event related potentials (ERPs) were recorded from 10 dyslexic participants (ages 15.5-17.4) and 10 control participants (ages 14.4-18.3) in the Continuous Performance Task (CPT), an established test of attentional performance. Participants were screened to ensure that none was diagnosable as attention deficit (ADHD). RESULTS: There were no significant differences in mean reaction time, error rate or sustained attention between the groups. By contrast, the P3 amplitude was significantly smaller and its latency significantly longer for the dyslexic group. This component was significantly lateralised in controls, whereas in dyslexics it was symmetrical. CONCLUSIONS: Under the relatively light workload conditions of the CPT, "pure" dyslexic participants showed no behavioural signs of attentional difficulties. The attenuated, delayed and symmetrical ERPs in our dyslexic group may reflect abnormal information processing in the right parietal lobe and abnormal interhemispheric asymmetry in Dyslexia. SIGNIFICANCE: The behavioural data suggest that abnormal attentional performance is not a "core" feature of developmental Dyslexia, and highlight the importance of distinguishing between dyslexic participants with and without ADHD symptoms. The presence of electrophysiological markers of Dyslexia in CPT revealed the atypical brain organisation that characterises "pure" Dyslexia.     

EEG and task performance after ACTH4-10 in man.

Effects of the heptapeptide ACTH4-10 (Org OI-63) on EEG, some memory tests, and behavior were examined in 12 normal male volunteers under 30 years of age. An intravenous dose of 60 mg was compared to placebo in a Latin square design. EEG was recorded for 2 h after administration of ACTH4-10 or placebo and was quantified by power spectral density analysis. Drug differences were tested by analyses of variance and covariance. No statistical drug effect was seen on the EEG or behavioral measures. Of the psychological tests, only the digit span test showed a decrease in number of errors with ACTH4-10 (p less than or equal to o.05). These results are consistent with previous studies and suggest that an intravenous bolus of ACTH4-10 has a limited effect on the brain function tested.     

The relation of visuospatial dysfunction to digit span performance in patients with cerebral lesions.

DSF and DSB performance was compared in hospitalized controls and right and left brain lesion groups dichotomized for the presence or absence of visuospatial deficits. Digit Span performance was also correlated with WAIS Similarities and Block Design and Raven Coloured Progressive Matrices. No differences between groups were observed on DSF. On DSB patients with brain lesions had lower scores than controls and brain-lesioned patients with visuospatial deficits had lower scores than those without. DSB correlated significantly with WAIS Block Design and Raven Coloured Progressive Matrices supporting the hypothesis that visuospatial ability is needed to mediate proper DSB performance. The correlation of DSB with WAIS Similarities, however, lends support to the idea that low DSB may merely reflect severity of cognitive deficit.