Testing Mean Differences among Groups: Multivariate and Repeated Measures Analysis with Minimal Assumptions.

To date, there is a lack of satisfactory inferential techniques for the analysis of multivariate data in factorial designs, when only minimal assumptions on the data can be made. Presently available methods are limited to very particular study designs or assume either multivariate normality or equal covariance matrices across groups, or they do not allow for an assessment of the interaction effects across within-subjects and between-subjects variables. We propose and methodologically validate a parametric bootstrap approach that does not suffer from any of the above limitations, and thus provides a rather general and comprehensive methodological route to inference for multivariate and repeated measures data. As an example application, we consider data from two different Alzheimer's disease (AD) examination modalities that may be used for precise and early diagnosis, namely, single-photon emission computed tomography (SPECT) and electroencephalogram (EEG). These data violate the assumptions of classical multivariate methods, and indeed classical methods would not have yielded the same conclusions with regards to some of the factors involved.

Between- and within-site variability of fMRI localizations.

This study provides first data about the spatial variability of fMRI sensorimotor localizations when investigating the same subjects at different fMRI sites. Results are comparable to a previous patient study. We found a median between-site variability of about 6 mm independent of task (motor or sensory) and experimental standardization (high or low). An intraclass correlation coefficient analysis using data quality measures indicated a major influence of the fMRI site on variability. In accordance with this, within-site localization variability was considerably lower (about 3 mm). We conclude that the fMRI site is a considerable confound for localization of brain activity. However, when performed by experienced clinical fMRI experts, brain pathology does not seem to have a relevant impact on the reliability of fMRI localizations. Hum Brain Mapp 37:2151-2160, 2016. © 2016 Wiley Periodicals, Inc.

Patterns of cognitive performance in Subcortical Ischemic Vascular Disease (SIVD).

Subcortical ischemic vascular disease (SIVD) is characterized by extensive white-matter lesions and lacunar infarcts in deep gray matter. The aim of this study was to investigate patterns of cognitive impairment in patients with SIVD. In a retrospective analysis, the authors compared the cognitive performance of 58 patients meeting MRI-defined criteria for SIVD (26 women; 47.3%) with age- and gender-matched control subjects. SIVD patients showed impairments in measures of verbal fluency, verbal memory, speed of cognitive processing, and divided attention. There were no significant differences in constructional praxis, figurative memory, verbal recognition memory, or semantic processing.

Variability of clinical functional MR imaging results: a multicenter study.

PURPOSE: To investigate intersite variability of clinical functional magnetic resonance (MR) imaging, including influence of task standardization on variability and use of various parameters to inform the clinician whether the reliability of a given functional localization is high or low. MATERIALS AND METHODS: Local ethics committees approved the study; all participants gave written informed consent. Eight women and seven men (mean age, 40 years) were prospectively investigated at three experienced functional MR sites with 1.5- (two sites) or 3-T (one site) MR. Nonstandardized motor and highly standardized somatosensory versions of a frequently requested clinical task (localization of the primary sensorimotor cortex) were used. Perirolandic functional MR variability was assessed (peak activation variability, center of mass [COM] variability, intraclass correlation values, overlap ratio [OR], activation size ratio). Data quality measures for functional MR images included percentage signal change (PSC), contrast-to-noise ratio (CNR), and head motion parameters. Data were analyzed with analysis of variance and a correlation analysis. RESULTS: Localization of perirolandic functional MR activity differed by 8 mm (peak activity) and 6 mm (COM activity) among sites. Peak activation varied up to 16.5 mm (COM range, 0.4-16.5 mm) and 45.5 mm (peak activity range, 1.8-45.5 mm). Signal strength (PSC, CNR) was significantly lower for the somatosensory task (mean PSC, 1.0% ± 0.5 [standard deviation]; mean CNR, 1.2 ± 0.4) than for the motor task (mean PSC, 2.4% ± 0.8; mean CNR, 2.9 ± 0.9) (P < .001, both). Intersite variability was larger with low signal strength (negative correlations between signal strength and peak activation variability) even if the task was highly standardized (mean OR, 22.0% ± 18.9 [somatosensory task] and 50.1% ± 18.8 [motor task]). CONCLUSION: Clinical practice and clinical functional MR biomarker studies should consider that the center of task-specific brain activation may vary up to 16.5 mm, with the investigating site, and should maximize functional MR signal strength and evaluate reliability of local results with PSC and CNR.

The platelet transcriptome and proteome in Alzheimer's disease and aging: an exploratory cross-sectional study.

Introduction: Alzheimer's disease (AD) and aging are associated with platelet hyperactivity. However, the mechanisms underlying abnormal platelet function in AD and aging are yet poorly understood. Methods: To explore the molecular profile of AD and aged platelets, we investigated platelet activation (i.e., CD62P expression), proteome and transcriptome in AD patients, non-demented elderly, and young individuals as controls. Results: AD, aged and young individuals showed similar levels of platelet activation based on CD62P expression. However, AD and aged individuals had a proteomic signature suggestive of increased platelet activation compared with young controls. Transcriptomic profiling suggested the dysregulation of proteolytic machinery involved in regulating platelet function, particularly the ubiquitin-proteasome system in AD and autophagy in aging. The functional implication of these transcriptomic alterations remains unclear and requires further investigation. Discussion: Our data strengthen the evidence of enhanced platelet activation in aging and provide a first glimpse of the platelet transcriptomic changes occurring in AD.

Cognitive Effects of Montelukast: A Pharmaco-EEG Study.

Montelukast is a well-established antiasthmatic drug with little side effects. It is a leukotriene receptor antagonist and recent research suggests cognitive benefits from its anti-inflammatory actions on the central nervous system. However, changes in brain activity were not directly shown so far in humans. This study aims to document changes in brain activity that are associated with cognitive improvement during treatment with Montelukast. We recorded EEG and conducted neuropsychological tests in 12 asthma-patients aged 38-73 years before and after 8 weeks of treatment with Montelukast. We found no significant changes on neuropsychological scales for memory, attention, and mood. In the EEG, we found decreased entropy at follow up during rest (p < 0.005). During episodic memory acquisition we found decreased entropy (p < 0.01) and acceleration of the background rhythm (p < 0.05). During visual attention performance, we detected an increase in gamma power (p < 0.005) and slowing of the background rhythm (p < 0.05). The study is limited by its small sample size, young age and absence of baseline cognitive impairment of the participants. Unspecific changes in brain activity were not accompanied by cognitive improvement. Future studies should examine elderly patients with cognitive impairment in a double-blind study with longer-term treatment by Montelukast.

Spontaneous subdural spinal haematoma presenting as occipital headache: a case report.

Spinal subdural hematoma (SSDH) with no underlying pathology is a very rare condition and has been rarely reported. Our patient presented with severe occipital headache as isolated symptom during the first 4 days. SSDH slowly enlarges with time, and first determines tension of the pain-sensitive dural membrane, resulting in cervicogenic-like headache. Therefore, spontaneous SSDH should be considered in the differential diagnosis of recent occipital headache.

Prediction of Cognitive Decline in Temporal Lobe Epilepsy and Mild Cognitive Impairment by EEG, MRI, and Neuropsychology.

Cognitive decline is a severe concern of patients with mild cognitive impairment. Also, in patients with temporal lobe epilepsy, memory problems are a frequently encountered problem with potential progression. On the background of a unifying hypothesis for cognitive decline, we merged knowledge from dementia and epilepsy research in order to identify biomarkers with a high predictive value for cognitive decline across and beyond these groups that can be fed into intelligent systems. We prospectively assessed patients with temporal lobe epilepsy (N = 9), mild cognitive impairment (N = 19), and subjective cognitive complaints (N = 4) and healthy controls (N = 18). All had structural cerebral MRI, EEG at rest and during declarative verbal memory performance, and a neuropsychological assessment which was repeated after 18 months. Cognitive decline was defined as significant change on neuropsychological subscales. We extracted volumetric and shape features from MRI and brain network measures from EEG and fed these features alongside a baseline testing in neuropsychology into a machine learning framework with feature subset selection and 5-fold cross validation. Out of 50 patients, 27 had a decline over time in executive functions, 23 in visual-verbal memory, 23 in divided attention, and 7 patients had an increase in depression scores. The best sensitivity/specificity for decline was 72%/82% for executive functions based on a feature combination from MRI volumetry and EEG partial coherence during recall of memories; 95%/74% for visual-verbal memory by combination of MRI-wavelet features and neuropsychology; 84%/76% for divided attention by combination of MRI-wavelet features and neuropsychology; and 81%/90% for increase of depression by combination of EEG partial directed coherence factor at rest and neuropsychology. Combining information from EEG, MRI, and neuropsychology in order to predict neuropsychological changes in a heterogeneous population could create a more general model of cognitive performance decline.

FUNDAMANT: an interventional 72-week phase 1 follow-up study of AADvac1, an active immunotherapy against tau protein pathology in Alzheimer's disease.

BACKGROUND: Neurofibrillary pathology composed of tau protein is closely correlated with severity and phenotype of cognitive impairment in patients with Alzheimer's disease and non-Alzheimer's tauopathies. Targeting pathological tau proteins via immunotherapy is a promising strategy for disease-modifying treatment of Alzheimer's disease. Previously, we reported a 24-week phase 1 trial on the active vaccine AADvac1 against pathological tau protein; here, we present the results of a further 72 weeks of follow-up on those patients. METHODS: We did a phase 1, 72-week, open-label study of AADvac1 in patients with mild to moderate Alzheimer's disease who had completed the preceding phase 1 study. Patients who were previously treated with six doses of AADvac1 at monthly intervals received two booster doses at 24-week intervals. Patients who were previously treated with only three doses received another three doses at monthly intervals, and subsequently two boosters at 24-week intervals. The primary objective was the assessment of long-term safety of AADvac1 treatment. Secondary objectives included assessment of antibody titres, antibody isotype profile, capacity of the antibodies to bind to AD tau and AADvac1, development of titres of AADvac1-induced antibodies over time, and effect of booster doses; cognitive assessment via 11-item Alzheimer's Disease Assessment Scale cognitive assessment (ADAS-Cog), Category Fluency Test and Controlled Oral Word Association Test; assessment of brain atrophy via magnetic resonance imaging (MRI) volumetry; and assessment of lymphocyte populations via flow cytometry. RESULTS: The study was conducted between 18 March 2014 and 10 August 2016. Twenty-six patients who completed the previous study were enrolled. Five patients withdrew because of adverse events. One patient was withdrawn owing to noncompliance. The most common adverse events were injection site reactions (reported in 13 [50%] of vaccinated patients). No cases of meningoencephalitis or vasogenic oedema were observed. New micro-haemorrhages were observed only in one ApoE4 homozygote. All responders retained an immunoglobulin G (IgG) antibody response against the tau peptide component of AADvac1 over 6 months without administration, with titres regressing to a median 15.8% of titres attained after the initial six-dose vaccination regimen. Booster doses restored previous IgG levels. Hippocampal atrophy rate was lower in patients with high IgG levels; a similar relationship was observed in cognitive assessment. CONCLUSIONS: AADvac1 displayed a benign safety profile. The evolution of IgG titres over vaccination-free periods warrants a more frequent booster dose regimen. The tendency towards slower atrophy in MRI evaluation and less of a decline in cognitive assessment in patients with high titres is encouraging. Further trials are required to expand the safety database and to establish proof of clinical efficacy of AADvac1. TRIAL REGISTRATION: The studies are registered with the EU Clinical Trials Register and ClinicalTrials.gov : the preceding first-in-human study under EudraCT 2012-003916-29 and NCT01850238 (registered on 9 May 2013) and the follow-up study under EudraCT 2013-004499-36 and NCT02031198 (registered 9 Jan 2014), respectively.

Combining SPECT and Quantitative EEG Analysis for the Automated Differential Diagnosis of Disorders with Amnestic Symptoms.

Single photon emission computed tomography (SPECT) and Electroencephalography (EEG) have become established tools in routine diagnostics of dementia. We aimed to increase the diagnostic power by combining quantitative markers from SPECT and EEG for differential diagnosis of disorders with amnestic symptoms. We hypothesize that the combination of SPECT with measures of interaction (connectivity) in the EEG yields higher diagnostic accuracy than the single modalities. We examined 39 patients with Alzheimer's dementia (AD), 69 patients with depressive cognitive impairment (DCI), 71 patients with amnestic mild cognitive impairment (aMCI), and 41 patients with amnestic subjective cognitive complaints (aSCC). We calculated 14 measures of interaction from a standard clinical EEG-recording and derived graph-theoretic network measures. From regional brain perfusion measured by 99mTc-hexamethyl-propylene-aminoxime (HMPAO)-SPECT in 46 regions, we calculated relative cerebral perfusion in these patients. Patient groups were classified pairwise with a linear support vector machine. Classification was conducted separately for each biomarker, and then again for each EEG- biomarker combined with SPECT. Combination of SPECT with EEG-biomarkers outperformed single use of SPECT or EEG when classifying aSCC vs. AD (90%), aMCI vs. AD (70%), and AD vs. DCI (100%), while a selection of EEG measures performed best when classifying aSCC vs. aMCI (82%) and aMCI vs. DCI (90%). Only the contrast between aSCC and DCI did not result in above-chance classification accuracy (60%). In general, accuracies were higher when measures of interaction (i.e., connectivity measures) were applied directly than when graph-theoretical measures were derived. We suggest that quantitative analysis of EEG and machine-learning techniques can support differentiating AD, aMCI, aSCC, and DCC, especially when being combined with imaging methods such as SPECT. Quantitative analysis of EEG connectivity could become an integral part for early differential diagnosis of cognitive impairment.

Reliability of EEG Interactions Differs between Measures and Is Specific for Neurological Diseases.

Alterations of interaction (connectivity) of the EEG reflect pathological processes in patients with neurologic disorders. Nevertheless, it is questionable whether these patterns are reliable over time in different measures of interaction and whether this reliability of the measures is the same across different patient populations. In order to address this topic we examined 22 patients with mild cognitive impairment, five patients with subjective cognitive complaints, six patients with right-lateralized temporal lobe epilepsy, seven patients with left lateralized temporal lobe epilepsy, and 20 healthy controls. We calculated 14 measures of interaction from two EEG-recordings separated by 2 weeks. In order to characterize test-retest reliability, we correlated these measures for each group and compared the correlations between measures and between groups. We found that both measures of interaction as well as groups differed from each other in terms of reliability. The strongest correlation coefficients were found for spectrum, coherence, and full frequency directed transfer function (average rho > 0.9). In the delta (2-4 Hz) range, reliability was lower for mild cognitive impairment compared to healthy controls and left lateralized temporal lobe epilepsy. In the beta (13-30 Hz), gamma (31-80 Hz), and high gamma (81-125 Hz) frequency ranges we found decreased reliability in subjective cognitive complaints compared to mild cognitive impairment. In the gamma and high gamma range we found increased reliability in left lateralized temporal lobe epilepsy patients compared to healthy controls. Our results emphasize the importance of documenting reliability of measures of interaction, which may vary considerably between measures, but also between patient populations. We suggest that studies claiming clinical usefulness of measures of interaction should provide information on the reliability of the results. In addition, differences between patient groups in reliability of interactions in the EEG indicate the potential of reliability to serve as a new biomarker for pathological memory decline as well as for epilepsy. While the brain concert of information flow is generally variable, high reliability, and thus, low variability may reflect abnormal firing patterns.

Safety and immunogenicity of the tau vaccine AADvac1 in patients with Alzheimer's disease: a randomised, double-blind, placebo-controlled, phase 1 trial.

BACKGROUND: Neurofibrillary pathology composed of tau protein is a main correlate of cognitive impairment in patients with Alzheimer's disease. Immunotherapy targeting pathological tau proteins is therefore a promising strategy for disease-modifying treatment of Alzheimer's disease. We have developed an active vaccine, AADvac1, against pathological tau proteins and assessed it in a phase 1 trial. METHODS: We did a first-in-man, phase 1, 12 week, randomised, double-blind, placebo-controlled study of AADvac1 with a 12 week open-label extension in patients aged 50-85 years with mild-to-moderate Alzheimer's disease at four centres in Austria. We randomly assigned patients with a computer-generated sequence in a 4:1 ratio overall to receive AADvac1 or placebo. They received three subcutaneous doses of AADvac1 or placebo from masked vaccine kits at monthly intervals, and then entered the open-label phase, in which all patients were allocated to AADvac1 treatment and received another three doses at monthly intervals. Patients, carers, and all involved with the trial were masked to treatment allocation. The primary endpoint was all-cause treatment-emergent adverse events, with separate analyses for injection site reactions and other adverse events. We include all patients who received at least one dose of AADvac1 in the safety assessment. Patients who had a positive IgG titre against the tau peptide component of AADvac1 at least once during the study were classified as responders. The first-in-man study is registered with EU Clinical Trials Register, number EudraCT 2012-003916-29, and ClinicalTrials.gov, number NCT01850238; the follow-up study, which is ongoing, is registered with EU Clinical Trials Register, number EudraCT 2013-004499-36, and ClinicalTrials.gov, number NCT02031198. FINDINGS: This study was done between June 9, 2013, and March 26, 2015. 30 patients were randomly assigned in the double-blind phase: 24 patients to the AADvac1 group and six to the placebo group. A total of 30 patients received AADvac1. Two patients withdrew because of serious adverse events. The most common adverse events were injection site reactions after administration (reported in 16 [53%] vaccinated patients [92 individual events]). No cases of meningoencephalitis or vasogenic oedema occurred after administration. One patient with pre-existing microhaemorrhages had newly occurring microhaemorrhages. Of 30 patients given AADvac1, 29 developed an IgG immune response. A geometric mean IgG antibody titre of 1:31415 was achieved. Baseline values of CD3+ CD4+ lymphocytes correlated with achieved antibody titres. INTERPRETATION: AADvac1 had a favourable safety profile and excellent immunogenicity in this first-in-man study. Further trials are needed to corroborate the safety assessment and to establish proof of clinical efficacy of AADvac1. FUNDING: AXON Neuroscience SE.

Evidence for a dysfunction of left posterior reading areas in German dyslexic readers.

The brain activity during a sentence reading task and a visual control task was examined with fMRI in 13 German dyslexic readers and 15 age-matched fluent readers (age: 14-16 years). These participants came from a longitudinal study and the dyslexic readers exhibited a persistent reading fluency deficit from early on. For the first time with German dyslexic readers, and in correspondence with the majority of functional imaging studies, we found reduced dyslexic activation in the left occipitotemporal cortex and in a small region of the left supramarginal gyrus. Enhanced activation was found in left inferior frontal and subcortical regions.

High prevalence and undertreatment of hypercholesterolaemia in participants in a public stroke prevention programme in austria.

BACKGROUND: There is remarkable consistency in large cohort studies regarding the relationship between serum cholesterol and the incidence of coronary heart disease (CHD), and increasing interest in the relationship between serum cholesterol and stroke. The aim of our investigation was to identify the prevalence and control of hypercholesterolaemia in participants in a public stroke prevention programme. PATIENTS AND METHODS: 9274 participants were categorised according to the guidelines of the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) and analysed with reference to risk category, treatment eligibility and treatment quality. RESULTS: NCEP-ATP III identifies low-density lipoprotein (LDL) cholesterol as the primary target of treatment. In this programme, 499 (5.4%) subjects were classified as having optimal (<100 mg/dL) LDL cholesterol levels, 1718 (18.5%) as near optimal (100-129 mg/dL), 2863 (30.9%) as borderline high (130-159 mg/dL), 2472 (26.7%) as high (160-189 mg/dL) and 1722 (18.6%) as very high (>190 mg/dL). 4442 (47.9%) participants presented with 0-1 risk factors, 2451(26.4%) with multiple (2+) risk factors, and 2381 (25.7%) met the criteria of secondary prevention. The suggested treatment goals were met in 2411 (54.3%) participants with 0-1 risk factors, in 561 (22.9%) of the multiple-risk-factor group, and in 148 (6.2%) subjects with established CHD or risk equivalents. A total of 871 subjects (9.4%) reported use of cholesterol-lowering drugs. CONCLUSIONS: We observed a considerable prevalence and poor control of hypercholesterolaemia in participants in a public stroke prevention programme in Austria.

Stimulating music increases motor coordination in patients afflicted with Morbus Parkinson.

The present study measured the short-term effect of special stimulating music on motor coordination in Parkinson patients. Eleven patients with a dominant akinetic Parkinson syndrome as well as ten healthy persons (age-matched control group) participated in this study. In the Parkinson group, the measurement of fine motor coordination with the 'Vienna Test System' showed an improvement in two (aiming, line tracking) of the four subtests after listening to the music. The patients improved their performance with the right arm significantly in the subtest aiming-error-time. No statistical differences were found in the other two subtests (steadiness, tapping) in both groups. There was also no improvement in frequency of tapping movement on the power-force-working-plate. Accordingly, music effects more the precision of a movement than the speediness. The measurements on the power-force-working-plate showed a significant improvement in two of five measured parameters: contact time, variability coefficient for total step and impact maximum changed significantly. This study gives evidence that specific music can improve the precision of arm and finger movements.

A placebo-controlled study of lofexidine in the treatment of children with tic disorders and attention deficit hyperactivity disorder.

This study evaluated the efficacy and safety of Lofexidine in treating children with tic disorders and attention deficit hyperactivity disorder (ADHD). Subjects from a specialty tic disorders clinic were randomly assigned to receive 8 weeks of treatment with lofexidine or placebo under double-blind conditions. Follow-up visits occurred every 2 weeks for safety monitoring and dose adjustment. Fourty-four medication-free subjects (41 boys and three girls; mean age of 10.4 years) with ADHD, combined type, and a tic disorder participated. After 8 weeks of treatment, lofexidine was associated with a mean improvement of 41% in the total score on the teacher-rated ADHD Rating Scale compared to 7% improvement for placebo. Eleven of 22 subjects who received lofexidine were blindly rated on the Clinical Global Scale-Improvement as either much improved or very much improved compared to none of 22 subjects who received placebo. The mean score on the parent-rated hyperactivity index improved by 29% in the lofexidine group and 18% in the placebo group, which was not a significant difference. On the Continuous Performance Test, commission errors decreased by 25% and omission errors by 20% in the lofexidine group, compared with increases of 33% in commission errors and of 36% in omission errors in the placebo group. Tic severity decreased by 27% in the lofexidine group, compared to 0% in the placebo group. One lofexidine subject with sedation withdrew at week 4. Lofexidine was associated with insignificant decreases in blood pressure and pulse. Lofexidine appears to be a safe and effective treatment for children with tic disorders and ADHD.

Comparison of disulfiram and placebo in treatment of alcohol dependence of adolescents.

About 50% of alcoholic patients relapse within 3 months of treatment. Previous studies have suggested that disulfiram may help to prevent such relapse. The aim of our study was to assess the efficacy and safety of long-term disulfiram treatment in alcohol dependence of adolescents. In this double-blind, placebo-controlled study we recruited 26 adolescents, aged 16-19 years, with chronic or episodic alcohol dependence. Patients were allocated treatment randomly with disulfiram (200 mg daily) or placebo for 90 days. Patients were assessed on the day treatment started and on days 30 and 90 by interview, self-report, questionnaire and laboratory screening. Patients were classified as abstinent, relapsing or non-attending. Time to first treatment failure (relapse or non-attendance) was the primary outcome measure. The disulfiram (n=13) and placebo (n=13) groups were well matched in terms of baseline demographic and alcohol-related variables. Thirteen disulfiram-treated and 13 placebo-treated patients completed the treatment phase; seven (1 vs. 6) relapsed, five (3 vs. 2) refused to continue treatment, three (1 vs. 2) had concurrent illness and two (1 vs. 1) had adverse side effects. At the end of treatment, seven disulfiram-treated and two placebo-treated patients had been abstinent continuously (p=0.0063). Mean cumulative abstinence duration was significantly greater in the disulfiram group than in the placebo group [68.5 (SD 37.5) vs. 29.7 (19.0) days; p=0.012]. Apart from occasional diarrhoea, there was no difference in side effects between groups. In some cases, disulfiram may be an effective and well-tolerated pharmacological adjunct to psychosocial and behavioural treatment programmes for treatment of adolescent alcohol-dependent patients.

Brain activation disturbance for target detection in patients with mild cognitive impairment: an fMRI study.

Functional brain imaging in mild cognitive impairment (MCI) reveals differences in activation of task-relevant brain areas between patients and age-matched healthy controls. However, some studies reported hyperactivation and others hypoactivation in MCI compared with controls. The inconsistencies may be explained by compensatory mechanisms due to high complexity of the applied tasks. The oddball task is a simple paradigm that is known to activate a widespread network in the brain, involving attentional and monitoring mechanisms. In the present study, we examined amnestic or amnestic multidomain MCI patients (n = 12) and healthy controls (n = 13) in an auditory oddball task. Participants had to respond to infrequent targets and inhibit response to infrequent novel-nontarget stimuli. Lower stimulus related activation was found in MCI patients compared with healthy controls in parts of the middle temporal gyrus, the temporal pole, regions along the superior temporal sulcus, in the left cuneus, the left supramarginal gyrus, the anterior cingulated cortex and in the left inferior and middle frontal gyrus. Activation for oddball stimuli is assumed to reflect an automatic reflexive engagement of many brain regions in response to potentially important changes in the environment as well as cognitive control to monitor responses. The mechanisms of attention and cognitive control may be severely impaired in MCI and thus, underlie the cognitive deficits of this clinical group.

Modulation of motor cortex excitability by different levels of whole-hand afferent electrical stimulation.

OBJECTIVE: In a previous transcranial magnetic stimulation (TMS) study we demonstrated that suprathreshold mesh-glove (MG) whole-hand stimulation elicits lasting changes in motor cortical excitability. Currently, there is no consensus with regard to the optimal parameters for the induction of sensorimotor cortical plasticity using peripheral electrical stimulation. Thus, in the present study we explore the modulatory effects of MG stimulation at different stimulus intensities and different frequencies in order to identify an optimal stimulation protocol. METHODS: MG stimulation was performed on 12 healthy subjects in separate sessions at different stimulation levels: sub-sensory at 50 Hz, sensory at 50 Hz and motor at 2 Hz. To verify if stimulation at lower frequencies is less effective, an additional experiment at sensory level with 2 Hz was performed. TMS was used to assess motor threshold (MT), motor evoked potentials (MEPs) recruitment curve (RC), short latency intracortical inhibition (SICI) and intracortical facilitation (ICF) to paired-pulse TMS at baseline (T0), immediately after (T1) and 1h (T2) after 30 min of MG stimulation. F-wave studies were performed to assess spinal motoneuron excitability. RESULTS: MG stimulation at sub-sensory/50 Hz and sensory/2 Hz level determines no significant cortical excitability changes; at sensory/50 Hz level and at motor/2 Hz level we found decreased MT, increased MEP RC as well as reduced SICI and increased ICF at T1 and T2. CONCLUSIONS: MG stimulation at sensory/50 Hz and motor/2 Hz level induces similar long-lasting modulatory effects on motor cortical excitability. Both the strength of the corticospinal projections and the intracortical networks are influenced to the same extend. SIGNIFICANCE: The study provides further evidence that stimulation intensity and frequency can independently modulate motor cortical plasticity. The selection of optimal stimulation parameters has potentially important implications for the neurorehabilitation of patients after brain damage (e.g. stroke, traumatic brain injury) with hand motor deficits.

Cerebral hypoperfusion during carotid artery stenosis can lead to cognitive deficits that may be independent of white matter lesion load.

Studies investigating cognitive impairment in stroke-free patients with carotid artery stenosis have led to inconsistent results. Furthermore, the pathophysiological mechanism leading to cognitive impairment remains unclear. Cerebral hypoperfusion and arterio-arterial microembolization are discussed. The aims of our study were (1) to delineate patterns of cognitive impairment in stroke-free patients with carotid artery stenosis and (2) to investigate if cognitive impairment is independent of white matter lesion load in brain MRI. We identified 212 (93 women, mean age 70.2) stroke free, non-demented patients, who were referred for carotid artery stenting or because of subjective cognitive impairment. All patients completed a neurocognitive test battery measuring verbal fluency, constructional praxis, figural memory, verbal short-term- and long-term-memory, verbal recognition memory, semantic processing, speed of cognitive processing and divided attention. Grade of maximum carotid artery stenosis was categorized into three groups (mild, moderate, or severe). White matter lesion load was graded using a visual rating scale. Cognitive test scores of groups with different grades of carotid artery stenosis were compared. Univariate regression analysis was used to measure the predictive value of carotid artery stenosis. Multivariate logistic regression analysis was performed when integrating carotid artery stenosis and white matter lesion load. Carotid artery stenosis negatively correlated with measures of verbal fluency, constructional praxis, verbal short-term-memory, semantic processing, speed of cognitive processing, and divided attention. After adjustment for white matter lesions, carotid artery stenosis did not independently predict divided attention. Significance persisted in all other cognitive domains. In our selected group of patients, a higher grade of carotid artery stenosis is associated with cognitive decline. This process is independent of white matter lesion load. Possible pathophysiological implications are discussed.