Brain networks construction using Bayes FDR and average power function.

Brain functional connectivity is a widely investigated topic in neuroscience. In recent years, the study of brain connectivity has been largely aided by graph theory. The link between time series recorded at multiple locations in the brain and the construction of a graph is usually an adjacency matrix. The latter converts a measure of the connectivity between two time series, typically a correlation coefficient, into a binary choice on whether the two brain locations are functionally connected or not. As a result, the choice of a threshold τ over the correlation coefficient is key. In the present work, we propose a multiple testing approach to the choice of τ that uses the Bayes false discovery rate and a new estimator of the statistical power called average power function to balance the two types of statistical error. We show that the proposed average power function estimator behaves well both in case of independence and weak dependence of the tests and it is reliable under several simulated dependence conditions. Moreover, we propose a robust method for the choice of τ using the 5% and 95% percentiles of the average power function and False Discovery Rate bootstrap distributions, respectively, to improve stability. We applied our approach to functional magnetic resonance imaging and high density electroencephalogram data.

Dissociative identity as a continuum from healthy mind to psychiatric disorders: Epistemological and neurophenomenological implications approached through hypnosis.

The topic of multiple personality, redefined as Dissociative Identity Disorders (DIDs) in the DSM-5, is an intriguing and still debated disorder with a long history and deep cultural and epistemological implications, extending up to the idea of possession. Hypnosis is an appealing and valuable model to manipulate subjective experience and get an insight on both the physiology and the pathophysiology of the mind-brain functioning; it and has been closely connected with DIDs and possession since its origin in 18th century and as recently proved the capacity to yield a loss of sense of agency, mimicking delusions of alien control and spirit possession. In this study we report on five very uncommon "hypnotic virtuosos" (HVs) free from any psychiatric disorder, spontaneously undergoing the emergence of multiple identities during neutral hypnosis; this allowed us to check the relationship between their experience and fMRI data. During hypnosis the subjects underwent spontaneous non-intrusive experiences of other selves which were not recalled after the end of the session, due to post-hypnotic amnesia. The fMRI showed a significant decrease of connectivity in the Default Mode Network (DMN) especially between the posterior cingulate cortex and the medial prefrontal cortex. Our results and their contrast with the available data on fMRI in DIDs allows to draw the hypothesis of a continuum between healthy mind - where multiple identities may coexist at unconscious level and may sometimes emerge to the consciousness - and DIDs, where multiple personalities emerge as dissociated, ostensibly autonomous components yielding impaired functioning, subject's loss of control and suffering. If this is the case, it seems more reasonable to refrain from seeking for a clear-cut limit between normality (anyway a conventional, statistical concept) and pathology, and accept a grey area in between, where ostensibly odd but non-pathological experiences may occur (including so-called non-ordinary mental expressions) without calling for treatment but, rather, for being properly understood.

Online meditation training for people with multiple sclerosis: A randomized controlled trial.

BACKGROUND: Multiple sclerosis (MS) has a relevant impact on quality of life (QOL) and is associated with increased risks of psychological morbidity. Mindfulness-based interventions (MBIs) are among the most studied interventions, although few well-conducted studies have tested them in this field. Furthermore, the participation in typical MBIs may be impaired by time and logistics. OBJECTIVE: We aimed to test the efficacy of an online MBI to improve QOL, psychological well-being, sleep, and fatigue. METHODS: We conducted a randomized controlled trial, in which 139 participants were randomly assigned to an MS-specific online mindfulness meditation intervention or to a psychoeducational (active control) group. Participants were assessed for QOL, depression, anxiety, sleep problems, and fatigue, at three different times: at recruitment, after 2 months, and after 6 months. RESULTS: In comparison to the control group, the experimental subjects reported higher QOL and lower depression, anxiety, and sleep problems at the end of intervention. However, after 6 months these group differences were no longer significant. CONCLUSION: An online MBI could be an effective psychological treatment for the promotion of well-being in MS in short-term. However, the lack of lasting effects requires the development of new strategies to support long-term changes.

Sympathetic skin response in multiple sclerosis: a meta-analysis of case-control studies.

The usefulness of sympathetic skin responses (SSR) in multiple sclerosis (MS) has been advocated by several studies in the last 20 years; however, due to a great heterogeneity of findings, a comprehensive meta-analysis of case-control studies is in order to pinpoint consistencies and investigate the causes of discrepancies. We searched MEDLINE, EMBASE and Cochrane databases for case-control studies comparing SSR absence frequency and latency between patients with MS and healthy controls. Thirteen eligible studies including 415 MS patients and 331 healthy controls were identified. The pooled analysis showed that SSR can be always obtained in healthy controls while 34% of patients had absent SSRs in at least one limb (95% CI 22-47%; p < 0.0001) but with considerable heterogeneity across studies (I 2 = 90.3%). Patients' age explained 22% of the overall variability and positive correlations were found with Expanded Disability Status Scale and disease duration. The pooled mean difference of SSR latency showed a significant increase in patients on both upper (193 ms; 95% CI 120-270 ms) and lower (350 ms; 95% CI 190-510 ms) extremities. We tested the discriminatory value of SSR latency thresholds defined as the 95% confidence interval (CI) upper bound of the healthy controls, and validated the results on a new dataset. The lower limb threshold of 1.964 s produces the best results in terms of sensitivity 0.86, specificity 0.67, positive predicted value 0.75 and negative predicted value 0.80. Despite a considerable heterogeneity of findings, there is evidence that SSR is a useful tool in MS.

Performance comparison between wrist and chest actigraphy in combination with heart rate variability for sleep classification.

The concurrent usage of actigraphy and heart rate variability (HRV) for sleep efficiency quantification is still matter of investigation. This study compared chest (CACT) and wrist (WACT) actigraphy (actigraphs positioned on chest and wrist, respectively) in combination with HRV for automatic sleep vs wake classification. Accelerometer and ECG signals were collected during polysomnographic studies (PSGs) including 18 individuals (25-53 years old) with no previous history of sleep disorders. Then, an experienced neurologist performed sleep staging on PSG data. Eleven features from HRV and accelerometry were extracted from series of different lengths. A support vector machine (SVM) was used to automatically distinguish sleep and wake. We found 7 min as the optimal signal length for classification, while maximizing specificity (wake detection). CACT and WACT provided similar accuracies (78% chest vs 77% wrist), larger than what yielded by HRV alone (66%). The addition of HRV to CACT reduced slightly the accuracy, while improving specificity (from 33% to 51%, p < 0.05). On the contrary, the concurrent usage of HRV and WACT did not provide statistically significant improvements over WACT. Then, a subset of features (3 from HRV + 1 from actigraphy) was selected by reducing redundancy using a strategy based on Spearman's correlation and area under the ROC curve. The usage of the reduced set of features and SVM classifier gave only slightly reduced classification performances, which did not differ from the full sets of features. The study opens interesting possibilities in the design of wearable devices for long-term monitoring of sleep at home.

A telemedicine meditation intervention for people with multiple sclerosis and their caregivers: study protocol for a randomized controlled trial.

BACKGROUND: Mindfulness-based interventions, modified and shortened versions of meditation teachings, have proved to be effective in the improvement of quality of life in many clinical conditions, including chronic diseases. Preliminary results available in the literature and in clinical experience indicate a high potential for this treatment for the reduction of psychological suffering in people with chronic diseases. METHODS/DESIGN: This randomized controlled trial will investigate the impact of a multiple sclerosis (MS) specific telemedicine meditation intervention on the quality of life of people with multiple sclerosis and their caregivers. This trial will recruit 120 patients, men and women, with a diagnosis of relapsing-remitting or secondary progressive MS and their caregivers to participate in a 2-month intervention. Patients will undergo assessments of quality of life, anxiety, depression, quality of sleep, mindfulness and fatigue levels conducted at baseline, at week 8 (conclusion of the intervention) and at week 27 (6 months follow-up). Caregivers will complete assessments conducted at the same time for the same areas, plus caregiver burden. The intervention condition will consist of 2 hours/week of online meditation in a group setting led by a trainer, plus 1 hour/week of individual exercises. The control condition will incorporate a psycho-education online program and will require the same contact time commitment as the intervention condition. DISCUSSION: Primary outcome measures will consist of assessments of quality of life, anxiety, and depression level. Assessments of mindfulness level, quality of sleep and fatigue level will be considered secondary outcome measures. This investigation will increase understanding of the role of meditation as part of a treatment plan for people with MS and their caregivers. Overall, this study design has the potential to lead to effective meditation intervention strategies for this population and improve their quality of life. TRIAL REGISTRATION: Clinical Trials Register NCT02364505. https://clinicaltrials.gov/ct2/show/NCT02364505.

The EP-score to assess treatment efficacy in RRMS patients: a preliminary study.

AIM OF THE STUDY: The aim of this retrospective study was to preliminarily assess whether the EP-score, a summary score derived from multimodal evoked potentials tests, might be used as a measure of treatment efficacy in multiple sclerosis (MS). MATERIALS AND METHODS: A sample of 56 relapsing remitting MS (RRMS) patients who at diagnosis started treatment with interferon ß (INFß, n = 19), glatiramer acetate (GA, n = 15) or refused any chronic treatment were assessed at baseline (before treatment) and at a median of 1.7 and 3.6 years thereafter. Outcome variables were Expanded Disability Status Scale (EDSS), EP-Score, visual evoked potentials (VEP) and somatosensory evoked potentials (SEP) scores measured as differences between baseline and follow-ups. Statistical differences between groups and follow-ups were assessed using non-parametric analyses. RESULTS: Treatment effects were not significant for EDSS both at the first and at the second follow-up, while a trend toward significance was observed in the EP-score only in the first follow-up (p = 0.07). Post-hoc analysis showed a greater decrease in median VEP-score for the IFNß group compared to the GA and DF groups at both the first and second follow-ups. CONCLUSIONS: We found no evidence that either INFß or GA significantly improved disability in RRMS patients. Using the EP-score as an outcome measure, we found that it was improved at both follow-ups in the INFß group mainly due to a decrease in the VEP-score. This finding supports the proposal to include the EP-score as an additional outcome variable in future studies of treatment efficacy in MS.

Exploring the predictive value of the evoked potentials score in MS within an appropriate patient population: a hint for an early identification of benign MS?

BACKGROUND: The prognostic value of evoked potentials (EPs) in multiple sclerosis (MS) has not been fully established. The correlations between the Expanded Disability Status Scale (EDSS) at First Neurological Evaluation (FNE) and the duration of the disease, as well as between EDSS and EPs, have influenced the outcome of most previous studies. To overcome this confounding relations, we propose to test the prognostic value of EPs within an appropriate patient population which should be based on patients with low EDSS at FNE and short disease duration. METHODS: We retrospectively selected a sample of 143 early relapsing remitting MS (RRMS) patients with an EDSS < 3.5 from a larger database spanning 20 years. By means of bivariate logistic regressions, the best predictors of worsening were selected among several demographic and clinical variables. The best multivariate logistic model was statistically validated and prospectively applied to 50 patients examined during 2009-2011. RESULTS: The Evoked Potentials score (EP score) and the Time to EDSS 2.0 (TT2) were the best predictors of worsening in our sample (Odds Ratio 1.10 and 0.82 respectively, p=0.001). Low EP score (below 15-20 points), short TT2 (lower than 3-5 years) and their interaction resulted to be the most useful for the identification of worsening patterns. Moreover, in patients with an EP score at FNE below 6 points and a TT2 greater than 3 years the probability of worsening was 10% after 4-5 years and rapidly decreased thereafter. CONCLUSIONS: In an appropriate population of early RRMS patients, the EP score at FNE is a good predictor of disability at low values as well as in combination with a rapid buildup of disability. Interestingly, an EP score at FNE under the median together with a clinical stability lasting more than 3 years turned out to be a protective pattern. This finding may contribute to an early identification of benign patients, well before the term required to diagnose Benign MS (BMS).

EEG evidence of posterior cortical disconnection in PD and related dementias.

Electroencephalogram (EEG) reactivity to eyes opening and 12-Hz photic stimulation was investigated in 14 healthy elderly subjects, 21 parkinsonian patients (PD), 7 demented parkinsonian patients (PDD), and 10 patients with Lewy body dementia (LBD) using global field synchronization (GFS). During eyes closed Theta GFS was increased in Parkinson's disease and patients and alpha1 GFS was decreased in LBD subjects. During 12-Hz intermittent photic stimulation (IPS), reactivity of posterior electrodes was decreased in PD and LBD patients. No reactivity was observed in PDD. Results are consistent with a graded posterior cortical disconnection in parkinsonian syndromes and with a model of dopamine-modulated thalamocortical interplay in visual processing.

Sleep disturbance and fatigue in mild relapsing remitting multiple sclerosis patients on chronic immunomodulant therapy: an actigraphic study.

BACKGROUND: Poor sleep is common in MS and it contributes to fatigue. The beta interferons produce systemic effects which may not adapt and may induce fatigue. OBJECTIVE: To verify whether subjective poor sleep and fatigue during chronic therapy correspond to reduced sleep efficiency obtained by actigraphy at home. METHODS: 42 ambulatory relapsing remitting MS patients with mild disability were monitored for at least 7 nights. Habitual sleep quality and fatigue were assessed with the MOS sleep measure and the Fatigue Severity Scale. Sleep logs provided daily sleep quality assessments during actigraphy at home. Patients were grouped according to their current treatment: no therapy, glatiramer acetate, IFNbeta 3 times a week, and IFNbeta once a week. RESULTS AND CONCLUSION: Sleep efficiency was reduced by an average of 5% in 2/3 of the nights following IFNbeta injections compared to the other nights, and daily sleep ratings correlated with actigraphy. Patients on glatiramer acetate also showed a lower sleep efficiency than patients without therapy. Actigraphy data were only modestly correlated with MOSsm scores, not with fatigue. Long term adaptation of sleep effects of immunomodulant agents is incomplete and needs to be considered in treatment planning and assessment of sleep in MS.