Responders to rTMS for depression show increased fronto-midline theta and theta connectivity compared to non-responders

Background

Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression, but only some individuals respond. Predicting response could reduce patient and clinical burden. Neural activity related to working memory (WM) has been related to mood improvements, so may represent a biomarker for response prediction.

Factor structure of the Cornell Scale for Depression in Dementia among Japanese poststroke patients

BACKGROUND: the present study reports on the first translation and use of the Cornell Scale for Depression in Dementia (CSDD) (Alexopoulos, Abrams, Young, & Shamoian, 1988) among poststroke patients (n = 101) in Japan. OBJECTIVES: the study had three main purposes: 1. To examine the factor structure of the CSDD among Japanese poststroke patients; 2. To compare this with the factor structure identified for Anglo-American Alzheimer's (AD) patients; and 3. To examine the prevalence and covariates of depressive symptoms among the Japanese stroke survivors. METHODS: poststroke patients and their caregivers (n = 202), at a random sample of neurological hospitals in western Japan, were interviewed using the study instruments. Data was also collected from patient charts. All subjects at each site who met the study criteria participated in the study. RESULTS: the four-factor solution for poststroke subjects was analogous to that found among AD patients with 2 main exceptions. In contrast to AD patients: 1. Physical complaints were unrelated to depressed mood in stroke patients; and 2. Agitation and psychosis loaded with depressed mood in stroke patients rather than as a separate unique factor as in AD patients. However, in the exploratory 5-factor model, agitation and suicidal ideation comprised a unique factor. Using standard cutoff scores for the CSDD, 58.2% of poststroke patients had scores suggesting possible depression. CSDD scores were not related to functional ability, or stroke characteristics such as aphasia or right or left-sided paralysis. However, scores were significantly higher among subjects < or = 2 years poststroke. Feelings of irritability, anxiety, sadness, and sleep problems were most prevalent. DISCUSSION: despite the prevalence of depressive symptoms, none of the subjects were currently receiving any mental health treatment. Findings suggest that symptoms differ by poststroke duration, which may necessitate different treatment approaches.     

EEG coherence in Alzheimer’s dementia

Summary. In Alzheimers dementia (AD) axonal disruption and cholinergic deficit lead to impaired cortical connectivity and to a decrease in EEG alpha coherence. The aim of the present study was to assess the usefulness of coherence parameters of the EEG for the diagnostics of AD. Quantitative EEG analyses were performed in 31 AD patients and 17 cognitively unimpaired depressive controls, both groups without psychopharmacological treatment. Differences between groups were examined and the diagnostic significance of EEG parameters was assessed by means of stepwise logistic regression analyses. In the AD patients global theta power was increased, left temporal alpha coherence and interhemispheric theta coherence were decreased. Left temporal alpha coherence and global theta power allowed an identification of AD patients with a sensitivity of 87% and a specificity of 77%. Quantitative analyses, especially the determination of left temporal alpha coherence, may enhance the usefulness of the EEG in the diagnostics of AD. Declaration of interest: Eisai GmbH, Frankfurt, supported S.B. in part during the studyReceived March 11, 2002; accepted June 10, 2002     

Reduced functional connectivity in visual evoked potentials in children with autism spectrum disorder

Objective

An analysis of EEG synchrony between homologous early visual areas tested the hypothesis that interhemispheric functional connectivity during visual stimulation is reduced in children with autism compared to controls.

Methods

EEG power and coherence within and between two homologous regions of the occipital cortex were measured during long latency flash visual evoked potentials. Measures were compared between two groups of children (5.5–8.5 years), one with autism spectrum disorders and the other with typical development.

Results

In and below the theta band, interhemispheric synchrony was reduced in autistic subjects compared to typical controls by as much as 50%. Above the theta band interhemispheric synchrony in autistic children became indistinguishable from what would occur for uncorrelated cortical activity. Interhemispheric synchrony in autistic subjects was decreased in spite of bilaterally increased power. Wavelet power showed autistic children had a more rapid initial response to stimulation, a slower recovery, and more modulation at longer latencies.

Conclusions

Results suggest that the sensory cortices of autistic children are hypersensitive to stimulation with concurrent diminished functional connectivity between hemispheres.

Significance

Simultaneously increased intrahemispheric power and decreased interhemispheric synchronization of elemental visual information suggests either that power increases cause poor interhemispheric connectivity or that processes, such as thalamocortical regulation, impact power and coherence independently.     

Preclinical examination of early-onset thalamic-cortical seizures after hemispheric stroke

Objective

Ischemic stroke is one of the main causes of death and disability worldwide and currently has limited treatment options. Electroencephalography (EEG) signals are significantly affected in stroke patients during the acute stage. In this study, we preclinically characterized the brain electrical rhythms and seizure activity during the hyperacute and late acute phases in a hemispheric stroke model with no reperfusion.

Methods

EEG signals and seizures were studied in a model of hemispheric infarction induced by permanent occlusion of the middle cerebral artery (pMCAO), which mimics the clinical condition of stroke patients with permanent ischemia. Electrical brain activity was also examined using a photothrombotic (PT) stroke model. In the PT model, we induced a similar (PT group-1) or smaller (PT group-2) cortical lesion than in the pMCAO model. For all models, we used a nonconsanguineous mouse strain that mimics human diversity and genetic variation.

Results

The pMCAO hemispheric stroke model exhibited thalamic-origin nonconvulsive seizures during the hyperacute stage that propagated to the thalamus and cortex. The seizures were also accompanied by progressive slowing of the EEG signal during the acute phase, with elevated delta/theta, delta/alpha, and delta/beta ratios. Cortical seizures were also confirmed in the PT stroke model of similar lesions as in the pMCAO model, but not in the PT model of smaller injuries.

Significance

In the clinically relevant pMCAO model, poststroke seizures and EEG abnormalities were inferred from recordings of the contralateral hemisphere (noninfarcted hemisphere), emphasizing the reciprocity of interhemispheric connections and that injuries affecting one hemisphere had consequences for the other. Our results recapitulate many of the EEG signal hallmarks seen in stroke patients, thereby validating this specific mouse model for the examination of the mechanistic aspects of brain function and for the exploration of the reversion or suppression of EEG abnormalities in response to neuroprotective and anti-epileptic therapies.     

Reduced fronto-cortical brain connectivity during NREM sleep in Asperger syndrome: An EEG spectral and phase coherence study

Objective

To investigate whether sleep macrostructure and EEG power spectral density and coherence during NREM sleep are different in Asperger syndrome (AS) compared to typically developing children and adolescents.

Methods

Standard all night EEG sleep parameters were obtained from 18 un-medicated subjects with AS and 14 controls (age range: 7.5–21.5 years) after one adaptation night. Spectral, and phase coherence measures were computed for multiple frequency bands during NREM sleep.

Results

Sleep latency and wake after sleep onset were increased in AS. Absolute power spectrum density (PSD) was significantly reduced in AS in the alpha, sigma, beta and gamma bands and in all 10 EEG derivations. Relative PSD showed a significant increase in delta and a decrease in the sigma band for frontal, and in beta for centro-temporal derivations. Intrahemispheric coherence measures were markedly lower in AS in the frontal areas, and the right hemisphere over all EEG channels. The most prominent reduction in intrahemispheric coherence was observed over the fronto-central areas in delta, theta, alpha and sigma EEG frequency bands.

Conclusion

EEG power spectra and coherence during NREM sleep, in particular in fronto-cortical derivations are different in AS compared to typically developing children and adolescents.

Significance

Quantitative analysis of the EEG during NREM sleep supports the hypothesis of frontal dysfunction in AS.     

Medial Temporal Atrophy and Memory Dysfunction in Poststroke Cognitive Impairment-No Dementia

Background and Purpose

It was recently reported that the prevalence of poststroke memory dysfunction might be higher than previously thought. Stroke may exist concomitantly with underlying Alzheimer''s disease (AD), and so we determined whether post-stroke memory dysfunction indicates manifestation of underlying subclinical AD.

Methods

Of 1201 patients in a prospective cognitive assessment database, we enrolled subjects with poststroke amnestic vascular cognitive impairment-no dementia (aVCIND; n=48), poststroke nonamnestic vascular cognitive impairment-no dementia (naVCIND; n=50), and nonstroke amnestic mild cognitive impairment (aMCI; n=65). All subjects had cognitive deficits, but did not meet the criteria for dementia. A standardized neuropsychological test battery and magnetic resonance imaging were performed at least 90 days after the index stroke (mean, 473 days). Visual assessment of medial temporal atrophy (MTA) was used as a measure of underlying AD pathology.

Results

The MTA score was significantly lower in the naVCIND group (0.64±0.85, mean±SD) than in the aVCIND (1.10±1.08) and aMCI (1.45±1.13; p<0.01) groups. Multivariable ordinal logistic regression analysis revealed that compared with naVCIND, aVCIND [odds ratio (OR)=2.69; 95% confidence interval (CI)=1.21-5.99] and aMCI (OR=5.20; 95% CI=2.41-11.23) were significantly associated with increasing severity of MTA.

Conclusions

Our findings show that compared with poststroke naVCIND, the odds of having more-severe MTA were increased for poststroke aVCIND and nonstroke aMCI.     

Organization of brain networks governed by long-range connections index autistic traits in the general population

Background

The dimensional approach to autism spectrum disorder (ASD) considers ASD as the extreme of a dimension traversing through the entire population. We explored the potential utility of electroencephalography (EEG) functional connectivity as a biomarker. We hypothesized that individual differences in autistic traits of typical subjects would involve a long-range connectivity diminution within the delta band.

Methods

Resting-state EEG functional connectivity was measured for 74 neurotypical subjects. All participants also provided a questionnaire (Social Responsiveness Scale, SRS) that was completed by an informant who knows the participant in social settings. We conducted multivariate regression between the SRS score and functional connectivity in all EEG frequency bands. We explored modulations of network graph metrics characterizing the optimality of a network using the SRS score.

Results

Our results show a decay in functional connectivity mainly within the delta and theta bands (the lower part of the EEG spectrum) associated with an increasing number of autistic traits. When inspecting the impact of autistic traits on the global organization of the functional network, we found that the optimal properties of the network are inversely related to the number of autistic traits, suggesting that the autistic dimension, throughout the entire population, modulates the efficiency of functional brain networks.

Conclusions

EEG functional connectivity at low frequencies and its associated network properties may be associated with some autistic traits in the general population.     

Additional value of quantitative EEG in acute anterior circulation syndrome of presumed ischemic origin

Objective

The clinical course of acute stroke can be highly variable and for effective management outcome prediction needs to be refined. We investigated whether EEG parameters are of additional diagnostic and prognostic value in the early phase of acute ischemic anterior circulation stroke.

Methods

Ninety-four patients presenting with acute anterior circulation syndrome (ACS) of presumed ischemic origin were incrementally included. Clinical characteristics were correlated with volume of ischemia and EEG parameters. Predictive values for definite stroke, early neurological deterioration, spontaneous early neurological improvement and death within 1 week after ACS were calculated using ROC curves and logistic regression modelling.

Results

In patients with normal or near normal NIHSS score of 0 or 1, the pairwise derived brain symmetry index (pdBSI) was an independent predictor for definite stroke displaying an overall accuracy of 80%. Early neurological deterioration was independently predicted by pdBSI with a correct classification rate of 95%. In ROC analysis, death was predicted by pdBSI with overall accuracy of 97%. Spontaneous neurological improvement was independently predicted by the delta + theta/alpha + beta – ratio with overall accuracy of 75%. Small-vessel stroke was independently predicted by pdBSI with a correct classification rate of 92%.

Conclusions

EEG may be of prognostic value for spontaneous neurological improvement, early neurological deterioration and death in the acute setting of acute anterior circulation syndrome of presumed ischemic origin.

Significance

These findings may have an impact on stroke care.     

Are early measured resting-state EEG parameters predictive for upper limb motor impairment six months poststroke?

ObjectivesInvestigate whether resting-state EEG parameters recorded early poststroke can predict upper extremity motor impairment reflected by the Fugl-Meyer motor score (FM-UE) after six months, and whether they have prognostic value in addition to FM-UE at baseline.MethodsQuantitative EEG parameters delta/alpha ratio (DAR), brain symmetry index (BSI) and directional BSI (BSIdir) were derived from 62-channel resting-state EEG recordings in 39 adults within three weeks after a first-ever ischemic hemispheric stroke. FM-UE scores were acquired within three weeks (FM-UE_baseline) and at 26 weeks poststroke (FM-UE_w26). Linear regression analyses were performed using a forward selection procedure to predict FM-UE_w26.ResultsBSI calculated over the theta band (BSI_theta) (β = −0.40; p = 0.013) was the strongest EEG-based predictor regarding FM-UE_w26. BSI_theta (β = −0.27; p = 0.006) remained a significant predictor when added to a regression model including FM-UE_baseline, increasing explained variance from 61.5% to 68.1%.ConclusionHigher BSI_theta values, reflecting more power asymmetry over the hemispheres, predict more upper limb motor impairment six months after stroke. Moreover, BSI_theta shows additive prognostic value regarding FM-UE_w26 next to FM-UE_baseline scores, and thereby contains unique information regarding upper extremity motor recovery.SignificanceTo our knowledge, we are the first to show that resting-state EEG parameters can serve as prognostic biomarkers of stroke recovery, in addition to FM-UE_baseline scores.     

Increase of theta/gamma ratio is associated with memory impairment

ObjectiveIn this study the theta/gamma ratio was investigated as early marker of cognitive decline.MethodsForty-nine subjects with mild cognitive impairment (MCI) underwent EEG recording and MRI scan. The theta/gamma ratio of the relative power at the peak frequency was computed. Based on the tertiles values of the ratio, three groups with increasing values of theta/gamma ratio were obtained. The groups were characterized by the performance on cognitive tests. Changes in functional brain connectivity, as expressed by interhemisperic and intrahemispheric EEG linear coherence in the groups were also evaluated.ResultsIncrease in theta/gamma ratio was associated with impairment in memory tests. This relationship was confirmed by correlation and multiple regression analysis. An independent association was found between theta/gamma ratio and alpha3/alpha2 power ratio. Coherence analysis showed modifications of interhemispheric functional coupling on temporal regions on slow frequencies.ConclusionsTheta/gamma ratio of relative power at peak frequency is significantly associated to memory decline. It could be a useful tool in detecting MCI subjects which are at major risk to develop Alzheimer’s disease (AD) or other dementias.SignificanceA global modulation of brain rhythms could be driven by the pathological alterations of theta/gamma ratio.     

Individual analysis of EEG background-activity within school age: impact of age and sex within a longitudinal data set

Objectives

Quantitative EEG can monitor changes in brain function during development and may help to understand developmental disorders. However, current EEG-databases are primarily based on standardized frequency bands which disregard age-related changes in alpha peak frequency (PF) and therefore complicate the interpretation of spectral estimates in the theta and alpha range.

Methods

We used a two point longitudinal design in order to analyze intraindividual changes in 40 healthy children and adolescents with age (T₁: 6-18 years; interval approximately 4 years). Using a 64-channel eyes closed resting EEG we calculated absolute/relative power in individualized frequency bands (IFB: delta, theta, alpha_1/2 and beta) based on PF.

Results

PF increased with age, with changes being larger for children than adolescents. Controlling for changes in PF, changes in absolute/relative alpha_1/2 power and in absolute beta power were minor. Relative beta power, however, increased while absolute/relative delta and theta power decreased massively.Sex-differences in PF did not reach significance. However, boys exhibited larger changes during adolescence than girls for all absolute power measures except alpha.

Conclusion

Normal EEG development during school-age is mainly based on an absolute decrease of slow frequency activity and increases of PF which may be interpreted in terms of a reorganization of the EEG towards a higher frequency oscillatory scale rather than a maturation of the theta-alpha_1/2 band power sequence. Age-related changes differed between boys and girls suggesting a different developmental timing for the sexes. In future studies a combined analysis of PF and IFB may help to specify deviations in developmental disorders.     

Prevalence of Balance Impairment Among Stroke Survivors Undergoing Neurorehabilitation in Nigeria

Background

Poststroke balance impairment adversely affects stroke outcomes and addressing the impairment is expected to constitute an important focus of neurorehabilitation.

Quantitative, waking EEG research on depression

Research published in the past decade that used quantitative indices to evaluate the waking EEG characteristics of depressed patients is reviewed. Methodological problems that make results of different research laboratories difficult to compare include diagnostic heterogeneity of depressed groups, lack of inclusion of control subjects, and differences in the EEG techniques. Despite interpretive problems that arise from such substantial variation, consistencies nevertheless emerge. Unmedicated, actively depressed patients appear to exhibit elevated EEG alpha and beta compared to control subjects. Delta and theta distinguished depressed patients from controls in some single studies, but variation in age, specific diagnostic depression categories, and EEG acquisition and analysis techniques rendered these results less definitive. Quantitative EEG differences that may distinguish depressed subject samples from those with other psychiatric disorders are considered. Factors that limit comparability of the findings are discussed in conjunction with strategies that deserve systematic study in future research.     

Region and frequency specific changes of spectral power in Alzheimer’s disease and mild cognitive impairment

Objectives

To find out whether healthy control (HC), amnestic mild cognitive impairment (aMCI), and Alzheimer’s disease (AD) subjects exhibit region and frequency specific spectral power differences and whether the spectral power changes correlate with domain-specific cognitive function.

Methods

Forty-one AD, 38 aMCI, and 39 HC subjects underwent quantitative EEG and comprehensive neuropsychological tests. Repeated measures analysis of variance was performed to identify differences in EEG spectral power among the three groups by scalp region and EEG frequency. Correlations between region and frequency specific spectral powers and neuropsychological test scores were evaluated.

Results

Temporal and parieto-occipital theta band powers were highest in AD. Whereas, parieto-occipital alpha and frontal and temporal beta 2 band powers were highest in HC and lowest in AD (p < 0.05). Temporal and parieto-occipital theta powers negatively correlated with verbal and visuospatial memory recall, while parieto-occipital alpha and temporal beta 2 powers positively correlated with verbal memory recall (p < 0.01).

Conclusions

Region and frequency specific oscillatory characteristics of EEG reflect domain-specific cognitive function in patients with aMCI and AD.

Significance

Region and frequency specific spectral powers have clinical implications as additional markers differentiating AD, aMCI, and HC.     

Exploring resting-state EEG brain oscillatory activity in relation to cognitive functioning in multiple sclerosis

Objective

Neurophysiologic monitoring parameters related to cognition in Multiple Sclerosis (MS) are sparse. Previous work reported an association between magnetoencephalographic (MEG) alpha-1 activity and information processing speed. While this remains to be replicated by more available electroencephalographic (EEG) methods, also other established EEG markers, e.g. the slow-wave/fast-wave ratio (theta/beta ratio), remain to be explored in this context.

Quantitative EEG and medial temporal lobe atrophy in Alzheimer's dementia: Preliminary study

Backgrounds:

The electroencephalogram (EEG) abnormalities in Alzheimer''s disease (AD) have been widely reported, and medial temporal lobe atrophy (MTLA) is one of the hallmarks in early stage of AD. We aimed to assess the relationship between EEG abnormalities and MTLA and its clinical validity.

Materials and Methods:

A total of 18 patients with AD were recruited (the mean age: 77.83 years). Baseline EEGs were analyzed with quantitative spectral analysis. MTLA was assessed by a T1-axial visual rating scale (VRS).

Results:

In relative power spectrum analysis according to the right MTLA severity, the power of theta waves in C4, T4, F4, F8, and T5 increased significantly and the power of beta waves in T6, C4, T4, F8, T5, P3, T3, and F7 decreased significantly in severe atrophy group. In relative power spectrum analysis according to the left MTLA severity, the power of theta waves in T3 increased significantly and that of beta waves in P4, T6, C4, F4, F8, T5, P3, C3, T3, F3, and F7 decreased significantly in severe atrophy group.

Conclusion:

The severe MTLA group, regardless of laterality, showed more severe quantitative EEG alterations. These results suggest that quantitative EEG abnormalities are correlated with the MTLA, which may play an important role in AD process.     

Quantitative EEG and apolipoprotein E-genotype improve classification of patients with suspected Alzheimer’s disease

Objective

To establish a model for better identification of patients in very early stages of Alzheimer’s disease, AD (including patients with amnestic MCI) using high-resolution EEG and genetic data.

Methods

A total of 26 patients in early stages of probable AD and 12 patients with amnestic MCI were included. Both groups were similar in age and education. All patients had a comprehensive neuropsychological examination and a high resolution EEG. Relative band power characteristics were calculated in source space (LORETA inverse solution for spectral data) and compared between groups. A logistic regression model was calculated including relative band-power at the most significant location, ApoE status, age, education and gender.

Results

Differences in the delta band at 34 temporo-posterior source locations (p < .01) between AD and MCI groups were detected after correction for multiple comparisons. Classification slightly increased when ApoE status was added (p = .06 maximum likelihood test). Adjustment of analyses for the confounding factors age, gender and education did not alter results.

Conclusions

Quantitative EEG (qEEG) separates between patients with amnestic MCI and patients in early stages of probable AD. Adding information about Apo ε4 allele frequency slightly enhances diagnostic accuracy.

Significance

qEEG may help identifying patients who are candidates for possible benefit from future disease modifying treatments.     

EEG power, frequency, asymmetry and coherence in male depression

Quantitative electroencephalographic (EEG) power topography has served as a useful tool for investigating brain regional mechanisms underlying affective disorders. In an attempt to examine the role of gender and widen the scope of the measurement probes used in these investigations, the traditional power and inter-hemispheric power ratio indices were supplemented with intra-hemispheric power ratios, mean frequency and both inter and intra-hemispheric coherence indices, in the comparison of depressed male patients and healthy controls. Resting (eyes closed), vigilance controlled EEG recordings from 21 scalp sites were collected from 70 male, unmedicated, unipolar major depressive disorder outpatients and 23 normal control male subjects. Absolute and relative power, frequency, asymmetry and coherence measures derived from spectrally analyzed EEGs were subjected to univariate analyses for group comparisons as well as to discriminant function analysis to examine their utility as classification indices. Compared with controls, patients evidenced greater overall relative beta power and, at bilateral anterior regions, greater absolute beta power and faster mean total spectrum frequency. Inter-hemispheric alpha power asymmetry index differences were noted, with controls exhibiting relatively reduced left hemisphere activation, and widespread reduced delta, theta, alpha and beta coherence indices. Whereas intra-hemispheric theta power asymmetry reduction was exhibited in patients bilaterally at all regions, group differences with intra-hemispheric beta power asymmetry were unilateral, being restricted to the right hemisphere. Discriminant analysis correctly classified 91.3% of the patients and controls. Quantitative EEG measurements in male depression appear to describe a pattern of aberrant inter-hemispheric synchrony/asymmetry and a profile of frontal activation.     

Resting-state EEG gamma activity in children with Attention-Deficit/Hyperactivity Disorder

Objective

Children with Attention-Deficit/Hyperactivity Disorder (AD/HD) have well-described abnormalities in the four traditional EEG bands. However, to date the gamma band has not been widely investigated. This study investigated resting-state EEG in children with AD/HD and matched controls, with a particular focus on gamma activity.

Method

Forty children with AD/HD, and 40 age- and sex-matched controls, participated. EEG was recorded from 19 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for absolute and relative power in the delta, theta, alpha, beta and gamma bands.

Results

Children with AD/HD had elevated levels of absolute delta and theta power, and decreased levels of absolute beta and gamma power, compared to controls. With relative power measures, children with AD/HD showed enhanced delta and theta activity, with reduced alpha, beta and gamma activity. Inattention scores on the Conners’ Parent Rating Scale were negatively correlated with absolute gamma.

Conclusions

These patients demonstrate the typical EEG profile in the eyes-closed resting state, over the delta, theta, alpha and beta bands, associated with AD/HD. In addition, compared with controls, they demonstrate reduced absolute and relative gamma activity. These differences appear to contribute importantly to their dysfunctional stimulus processing, and impact their behavioural outcomes.

Significance

This resting-state study extends the well-established fast-wave EEG deficits in children with AD/HD to the gamma band, and links that to increased inattention, which is of special importance in understanding their cognitive-processing problems.