Measuring clinically relevant change in apathy symptoms in ADMET and ADMET 2.

OBJECTIVES: Among participants with Alzheimer's disease (AD) we estimated the minimal clinically important difference (MCID) in apathy symptom severity on three scales. DESIGN: Retrospective anchor- and distribution-based analyses of change in apathy symptom scores. SETTING: Apathy in Dementia Methylphenidate Trial (ADMET) and ADMET 2 randomized controlled trials conducted at three and ten clinics specialized in dementia care in United States and Canada, respectively. PARTICIPANTS: Two hundred and sixty participants (60 ADMET, 200 ADMET 2) with clinically significant apathy in Alzheimer's disease. MEASUREMENTS: The Clinical Global Impression of Change in Apathy scale was used as the anchor measure and the MCID on the Neuropsychiatric Inventory - Apathy (NPI-A), Dementia Apathy Interview and Rating (DAIR), and Apathy Evaluation Scale-Informant (AES-I) were estimated with linear mixed models across all study visits. The estimated thresholds were evaluated with performance metrics. RESULTS: Among the MCID was a decrease of four points (95% CI: -4.0 to -4.8) on the NPI-A, 0.56 points (95% CI: -0.47 to -0.65) on the DAIR, and three points on the AES-I (95% CI: -0.9 to -5.4). Distribution-based analyses were largely consistent with the anchor-based analyses. The MCID across the three measures showed ∼60% accuracy. Sensitivity analyses found that MMSE scores and apathy severity at baseline influenced the estimated MCID. CONCLUSIONS: MCIDs for apathy on three scales will help evaluate treatment efficacy at the individual level. However, the modest correspondence between MCID and clinical impression of change suggests the need to consider other scales.

Alterations in Gray Matter Structural Networks in Amnestic Mild Cognitive Impairment: A Source-Based Morphometry Study.

Background: Amnestic mild cognitive impairment (aMCI), considered as the prodromal stage of Alzheimer's disease, is characterized by isolated memory impairment and cerebral gray matter volume (GMV) alterations. Previous structural MRI studies in aMCI have been mainly based on univariate statistics using voxel-based morphometry. Objective: We investigated structural network differences between aMCI patients and cognitively normal older adults by using source-based morphometry, a multivariate approach that considers the relationship between voxels of various parts of the brain. Methods: Ninety-one aMCI patients and 80 cognitively normal controls underwent structural MRI and neuropsychological assessment. Spatially independent components (ICs) that covaried between participants were estimated and a multivariate analysis of covariance was performed with ICs as dependent variables, diagnosis as independent variable, and age, sex, education level, and site as covariates. Results: aMCI patients exhibited reduced GMV in the precentral, temporo-cerebellar, frontal, and temporal network, and increased GMV in the left superior parietal network compared to controls (pFWER < 0.05, Holm-Bonferroni correction). Moreover, we found that diagnosis, more specifically aMCI, moderated the positive relationship between occipital network and Mini-Mental State Examination scores (pFWER < 0.05, Holm-Bonferroni correction). Conclusions: Our results showed GMV alterations in temporo-fronto-parieto-cerebellar networks in aMCI, extending previous results obtained with univariate approaches.

Sex-specific neuropsychological correlates of apathy and depression across neurodegenerative disorders.

BACKGROUND: Apathy and depression are common neuropsychiatric symptoms across neurodegenerative disorders and are associated with impairment in several cognitive domains, yet little is known about the influence of sex on these relationships. OBJECTIVES: We examined the relationship between these symptoms with neuropsychological performance across a combined cohort with mild or major neurodegenerative disorders, then evaluated the impact of sex. DESIGN, SETTING AND PARTICIPANTS: We conducted a cohort analysis of participants in the COMPASS-ND study with mild cognitive impairment (MCI), vascular MCI, Alzheimer's disease, mixed dementia, Parkinson's disease, frontotemporal dementia, and cognitively unimpaired (CU) controls. MEASUREMENTS: Participants with neurodegenerative disease and CU controls were stratified by the presence (severity ≥1 on Neuropsychiatric Inventory Questionnaire) of either depressive symptoms alone, apathy symptoms alone, both symptoms, or neither. A neuropsychological battery evaluated executive function, verbal fluency, verbal learning, working memory, and visuospatial reasoning. Analysis of covariance was used to assess group differences with age, sex, and education as covariates. RESULTS: Groups included depressive symptoms only (n = 70), apathy symptoms only (n = 52), both (n = 68), or neither (n = 262). The apathy and depression + apathy groups performed worse than the neither group on tests of working memory (t(312)  = -2.4, p = 0.02 and t(328)  = -3.8, p = 0.001, respectively) and visuospatial reasoning (t(301)  = -2.3, p = 0.02 and t(321)  = -2.6, p = 0.01, respectively). The depression, apathy, and depression + apathy groups demonstrated a similar degree of impairment on tests of executive function, processing speed, verbal fluency, and verbal learning when compared to participants without apathy or depression. Sex-stratified analyses revealed that compared to the male neither group, the male apathy and depression + apathy groups were impaired broadly across all cognitive domains except for working memory. Females with depression alone showed deficits on tests of executive function (t(166)  = 2.4, p = 0.01) and verbal learning (t(167)  = -4.3, p = 0.001) compared to the female neither group. CONCLUSIONS: This study demonstrated that in neurodegenerative diseases, apathy with or without depression in males was associated with broad cognitive impairments. In females, depression was associated with deficits in executive function and verbal learning. These findings highlight the importance of effectively treating apathy and depression across the spectrum of neurodegenerative disorders with the goal of optimizing neuropsychological outcomes.

Heterogeneity of Response to Methylphenidate in Apathetic Patients in the ADMET 2 Trial.

OBJECTIVE: The Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) found that methylphenidate was effective in treating apathy with a small-to-medium effect size but showed heterogeneity in response. We assessed clinical predictors of response to help determine individual likelihood of treatment benefit from methylphenidate. DESIGN: Univariate and multivariate analyses of 22 clinical predictors of response chosen a priori. SETTING: Data from the ADMET 2 randomized, placebo controlled multi-center clinical trial. PARTICIPANTS: Alzheimer's disease patients with clinically significant apathy. MEASUREMENTS: Apathy assessed with the Neuropsychiatric Inventory apathy domain (NPI-A). RESULTS: In total, 177 participants (67% male, mean [SD] age 76.4 [7.9], mini-mental state examination 19.3 [4.8]) had 6-months follow up data. Six potential predictors met criteria for inclusion in multivariate modeling. Methylphenidate was more efficacious in participants without NPI anxiety (change in NPI-A -2.21, standard error [SE]:0.60) or agitation (-2.63, SE:0.68), prescribed cholinesterase inhibitors (ChEI) (-2.44, SE:0.62), between 52 and 72 years of age (-2.93, SE:1.05), had 73-80 mm Hg diastolic blood pressure (-2.43, SE: 1.03), and more functional impairment (-2.56, SE:1.16) as measured by the Alzheimer's Disease Cooperative Study Activities of Daily Living scale. CONCLUSION: Individuals who were not anxious or agitated, younger, prescribed a ChEI, with optimal (73-80 mm Hg) diastolic blood pressure, or having more impaired function were more likely to benefit from methylphenidate compared to placebo. Clinicians may preferentially consider methylphenidate for apathetic AD participants already prescribed a ChEI and without baseline anxiety or agitation.

Lipopolysaccharide, Immune Biomarkers and Cerebral Amyloid-Beta Deposition in Older Adults With Mild Cognitive Impairment & Major Depressive Disorder.

OBJECTIVE: Inflammatory activation and increased immune response to lipopolysaccharide occur in both depression and cognitive decline and may link these two conditions. We investigated whether lipopolysaccharide (LPS), LPS binding protein (LBP) and peripheral biomarkers of immune response were associated with increased cerebral deposition of amyloid-beta (Abeta) in older adults with mild cognitive impairment (MCI) and remitted major depressive disorder (rMDD). DESIGN: Cross-sectional analysis. SETTING: Five academic health centers in Toronto. PARTICIPANTS: Older adults with MCI with/without rMDD. MEASUREMENTS: We investigated the associations among serum LPS, LBP, biomarkers of inflammatory activation - Interleukin-6 (IL-6), C-reactive protein (CRP), monocyte chemoattractant protein-1 (MCP-1), and cerebral Abeta deposition quantified by positron emission tomography. RESULTS: Among 133 study participants (82 with MCI and 51 with MCI+rMDD) there was no association between LPS (beta - 0.17, p = 0.8) or LBP (beta - 0.11, p = 0.12) and global deposition of Abeta following adjustment for age, gender, and APOE genotype in multivariable regression analyses. LBP was positively correlated with CRP (r = 0.5, p <0.001) and IL-6 (r = 0.2, p = 0.02) but no inflammatory biomarker was associated with Abeta deposition; rMDD was not associated with deposition of Abeta (beta -0.09, p = 0.22). CONCLUSION: In this cross-sectional analysis, we did not find an association among LPS/LBP, immune biomarkers or rMDD and global deposition of Abeta. Future analyses should assess the longitudinal relationships between peripheral and central biomarkers of immune activation, depression and cerebral Abeta deposition.

Identifying factors influencing cognitive outcomes after anodal transcranial direct current stimulation in older adults with and without cognitive impairment: A systematic review.

Anodal transcranial direct current stimulation (tDCS) can improve cognition in healthy older adults, those with Alzheimer's disease (AD) and mild cognitive impairment (MCI), albeit with considerable variability in response. This systematic review identifies interindividual factors that may influence tDCS outcomes in older individuals with or without cognitive impairment. Peer-reviewed articles were included if they assessed whether cognitive outcomes (memory or global cognition) after tDCS were associated with pre-intervention factors in healthy older adults or individuals with AD/MCI. We identified eight factors that may affect cognitive outcomes after tDCS. Improved tDCS outcomes were predicted by lower baseline cognitive function when tDCS was combined with a co-intervention (but not when used alone). Preserved brain structure and better baseline functional connectivity, genetic polymorphisms, and the use of concomitant medications may predict better tDCS outcomes, but further research is warranted. tDCS outcomes were not consistently associated with age, cognitive reserve, sex, and AD risk factors. Accounting for individual differences in baseline cognition, particularly for combined interventions, may thus maximize the therapeutic potential of tDCS.

The Relationship between Oxidative Stress and Subjective Sleep Quality in People with Coronary Artery Disease.

BACKGROUND: (1) Sleep disorders are prevalent in coronary artery disease (CAD) patients and predict cardiac events and prognosis. While increased oxidative stress (OS) has been associated with sleep disorders, less is known about its relationship with sleep quality. Similarly, little is known of how this relationship might change with exercise, which can improve sleep quality. Factors of sleep quality, such as sleep duration and disturbances, are also important as they predict cardiovascular diseases better than a global score alone. This study investigated whether OS was associated with self-rated sleep quality and its factors before and after completing a 24-week exercise intervention. (2) Methods: CAD patients undergoing an exercise program were recruited. OS was measured at baseline by the concentrations of early- (lipid hydroperoxides, LPH) and late-stage (8-isoprostane, 8-ISO) lipid peroxidation products and their ratio. Sleep quality was measured by the self-reported Pittsburgh Sleep Quality Index (PSQI) instrument at baseline and termination. Three sleep factors-perceived sleep quality, sleep efficiency, and daily disturbances-were derived from the PSQI. (3) Results: Among CAD patients (n = 113, 85.0% male, age = 63.7 ± 6.4 years, global PSQI = 5.8 ± 4.0), those with poor sleep (PSQI ≥ 5) had higher baseline 8-ISO levels (F(1, 111) = 6.212, p = 0.014, ηp2 = 0.053) compared to those with normal sleep. Concentrations of LPH (F(1, 105) = 0.569, p = 0.453, ηp2 = 0.005) and 8-ISO/LPH ratios (F(1, 105) = 2.173, p = 0.143, ηp2 = 0.020) did not differ between those with poor sleep and normal sleep. Among factors, perceived sleep quality was associated with 8-ISO and 8-ISO/LPH, and daily disturbances were associated with 8-ISO. (4) Conclusions: A marker of late-stage lipid peroxidation is elevated in CAD patients with poor sleep and associated with daily disturbances, but not with other factors or with sleep quality and its factors after exercise intervention.

From temporal to spatial topography: hierarchy of neural dynamics in higher- and lower-order networks shapes their complexity.

The brain shows a topographical hierarchy along the lines of lower- and higher-order networks. The exact temporal dynamics characterization of this lower-higher-order topography at rest and its impact on task states remains unclear, though. Using 2 functional magnetic resonance imaging data sets, we investigate lower- and higher-order networks in terms of the signal compressibility, operationalized by Lempel-Ziv complexity (LZC). As we assume that this degree of complexity is related to the slow-fast frequency balance, we also compute the median frequency (MF), an estimation of frequency distribution. We demonstrate (i) topographical differences at rest between higher- and lower-order networks, showing lower LZC and MF in the former; (ii) task-related and task-specific changes in LZC and MF in both lower- and higher-order networks; (iii) hierarchical relationship between LZC and MF, as MF at rest correlates with LZC rest-task change along the lines of lower- and higher-order networks; and (iv) causal and nonlinear relation between LZC at rest and LZC during task, with MF at rest acting as mediator. Together, results show that the topographical hierarchy of lower- and higher-order networks converges with their temporal hierarchy, with these neural dynamics at rest shaping their range of complexity during task states in a nonlinear way.

Medical Cannabis Use Among Older Adults in Canada: Self-Reported Data on Types and Amount Used, and Perceived Effects.

BACKGROUND: Medical cannabis use is growing among older adults. In this retrospective study, we aimed to assess the characteristics of older medical cannabis users including the indications, type and amount of cannabis used, perceived changes in symptoms after cannabis use, change in dose of concurrent medications, and adverse effects. METHODS: Data were collected between October 2014 and October 2020 from patients who were consulting the Canada-wide network of clinics of a medical cannabis provider and who were willing to answer questionnaires based on their medical status. The current study included older adults (≥ 65 years) who completed questionnaires at intake and first follow-up visits. Data were summarized with descriptive statistics, which were compared between men and women with t tests or chi-squared tests. Tests of proportions assessed categorical responses for perceived effects after cannabis use. Logistic regression was used to assess trends in cannabis usage. RESULTS: Data included that from 9766 older adult users at intake (mean ± SD age = 73.2 ± 6.8 years, females = 60.0%), among whom 4673 (females = 61.4%) returned for follow-up after 90.6 ± 58 days. The most common primary indication for which medical cannabis was sought was pain (67.7%), which was more common in women, whereas oncological and neurological conditions were more common in men. At follow-up, cannabis oil was used by 81.0% of older adults, among whom compositions containing only or mostly cannabidiol (CBD) had been used by 83.6%. Adverse effects reported by older adults at the follow-up visit included dry mouth (12.8%), drowsiness (8.6%), and dizziness (4.0%). The majority of older adults reported improvements in pain (72.7%, z = 1482.6, p < 0.0001, compared to worsening or no change), sleep (64.5%, z = 549.4, p < 0.0001), and mood (52.8%, z = 16.4, p < 0.0001), with 35.6% reporting use of a reduced dose of opioids and 19.9% a reduced dose of benzodiazepines. INTERPRETATION: Among older adults, medical cannabis is used more often by women, with CBD-containing cannabis oils being the most commonly used. Users reported improved pain, sleep, and mood symptoms at follow-up after cannabis use. This study describes the patterns of use of medical cannabis by older adults and highlights the need for research to determine appropriate indications, precise doses of active ingredients, and short- and long-term outcomes among older adults.

Blood-based biomarkers of agitation in Alzheimer's disease: Advances and future prospects.

Agitation is a common neuropsychiatric symptom that becomes more prevalent as Alzheimer's disease (AD) increases in severity. The treatment of agitation is an urgent and unmet need due to the poor outcomes associated with it, its disruptive impact on patients and caregivers, and the lack of efficacious and safe treatments. Recent research on agitation in AD with blood-based biomarkers has advanced the search for its biomarkers beyond the brain and provides new insights to understand its mechanisms and improve treatments. Here, we reviewed studies of blood-based biomarkers of agitation in AD, which show that inflammatory biomarkers are increased in patients with agitation, may predict the development of agitation, and are associated with symptom severity. In addition, they may also track symptom severity and response to treatment. Other biomarkers associated with agitation include markers of oxidative stress, brain cholesterol metabolism, motor activity, and clusterin, a chaperone protein. These results are promising and need to be replicated. Preliminary evidence suggests a role for these biomarkers in interventional studies for agitation to predict and monitor treatment response, which may eventually help enrich study samples and deliver therapy likely to benefit individual patients. Advances in blood-based biomarkers of AD including those identified in "-omic" studies and high sensitivity assays provide opportunities to identify new biomarkers of agitation. Future studies of agitation and its treatment should investigate blood-based biomarkers to yield novel insights into the neurobiological mechanisms of agitation, monitoring symptoms and response to treatment, and to identify patients likely to respond to treatments.

Planning in amnestic mild cognitive impairment: an fMRI study.

INTRODUCTION: The memory impairment that is characteristic of amnestic mild cognitive impairment (aMCI) is often accompanied by difficulties in executive functioning, including planning. Though planning deficits in aMCI are well documented, their neural correlates are largely unknown, and have not yet been investigated with functional magnetic resonance imaging (fMRI). OBJECTIVES: The aim of this study was to: (1) identify differences in brain activity and connectivity during planning between people with aMCI and cognitively healthy older adults, and (2) find whether planning-related activity and connectivity are associated with cognitive performance and symptoms of apathy. METHODS: Twenty-five people with aMCI and 15 cognitively healthy older adults performed a visuospatial planning task (Tower of London; ToL) during fMRI. Task-related brain activation, spatial maps of task-related independent components, and seed-to-voxel functional connectivity were compared between the two groups and regressed against measures of executive functions (Trail Making Test difference score, TMT B-A; Digit Symbol Substitution Test, DSST), delayed recall (Rey Auditory Verbal Learning Test), and apathy (Apathy Evaluation Scale). RESULTS: People with aMCI scored lower on task-switching (TMT B-A), working memory (DSST), and planning (ToL). During planning, people with aMCI had less activation in the bilateral anterior calcarine sulcus/cuneus, the bilateral temporal cortices, the left precentral gyrus, the thalamus, and the right cerebellum. Across all participants, higher planning-related activity in the supplementary motor area, the retrosplenial cortex and surrounding areas, and the right temporal cortex was related to better delayed recall. There were no between-group differences in functional connectivity, nor were there any associations between connectivity and cognition. We also did not find any associations between brain activity or connectivity and apathy. CONCLUSION: Impaired planning in people with aMCI appears to be accompanied by lower activation in a diffuse cortico-thalamic network. Across all participants, higher planning-related activity in parieto-occipital, temporal, and frontal areas was related to better memory performance. The results point to the relevance of planning deficits for understanding aMCI and extend its clinical and neurobiological signature.

Prestimulus dynamics blend with the stimulus in neural variability quenching.

Neural responses to the same stimulus show significant variability over trials, with this variability typically reduced (quenched) after a stimulus is presented. This trial-to-trial variability (TTV) has been much studied, however how this neural variability quenching is influenced by the ongoing dynamics of the prestimulus period is unknown. Utilizing a human intracranial stereo-electroencephalography (sEEG) data set, we investigate how prestimulus dynamics, as operationalized by standard deviation (SD), shapes poststimulus activity through trial-to-trial variability (TTV). We first observed greater poststimulus variability quenching in those real trials exhibiting high prestimulus variability as observed in all frequency bands. Next, we found that the relative effect of the stimulus was higher in the later (300-600ms) than the earlier (0-300ms) poststimulus period. Lastly, we replicate our findings in a separate EEG dataset and extend them by finding that trials with high prestimulus variability in the theta and alpha bands had faster reaction times. Together, our results demonstrate that stimulus-related activity, including its variability, is a blend of two factors: 1) the effects of the external stimulus itself, and 2) the effects of the ongoing dynamics spilling over from the prestimulus period - the state at stimulus onset - with the second dwarfing the influence of the first.

Temporal hierarchy of intrinsic neural timescales converges with spatial core-periphery organization.

The human cortex exhibits intrinsic neural timescales that shape a temporal hierarchy. Whether this temporal hierarchy follows the spatial hierarchy of its topography, namely the core-periphery organization, remains an open issue. Using magnetoencephalography data, we investigate intrinsic neural timescales during rest and task states; we measure the autocorrelation window in short (ACW-50) and, introducing a novel variant, long (ACW-0) windows. We demonstrate longer ACW-50 and ACW-0 in networks located at the core compared to those at the periphery with rest and task states showing a high ACW correlation. Calculating rest-task differences, i.e., subtracting the shared core-periphery organization, reveals task-specific ACW changes in distinct networks. Finally, employing kernel density estimation, machine learning, and simulation, we demonstrate that ACW-0 exhibits better prediction in classifying a region's time window as core or periphery. Overall, our findings provide fundamental insight into how the human cortex's temporal hierarchy converges with its spatial core-periphery hierarchy.

Widespread white matter aberration is associated with the severity of apathy in amnestic Mild Cognitive Impairment: Tract-based spatial statistics analysis.

Apathy is recognized as a prevalent behavioral symptom of amnestic Mild Cognitive Impairment (aMCI). In aMCI, apathy is associated with an increased risk and increases the risk of progression to Alzheimer's Disease (AD). Previous DTI study in aMCI showed that apathy has been associated with white matter alterations in the cingulum, middle and inferior longitudinal fasciculus, fornix, and uncinate fasciculus. However, the underlying white matter correlates associated with apathy in aMCI are still unclear. We investigated this relationship using whole-brain diffusion tensor imaging (DTI). Twenty-nine aMCI patients and 20 matched cognitively healthy controls were included. Apathy severity was assessed using the Apathy Evaluation Scale Clinician version. We applied the tract-based spatial statistics analyses to DTI parameters: fractional anisotropy (FA), mean diffusivity, axial diffusivity, and radial diffusivity to investigate changes in white matter pathways associated with the severity of apathy. No significant difference was found in any of the DTI parameters between aMCI and the control group. In aMCI, higher severity of apathy was associated with lower FA in various white matter pathways including the left anterior part of inferior fronto-occipital fasciculus/uncinate fasciculus, genu and body of the corpus callosum, superior and anterior corona radiata, anterior thalamic radiation of both hemispheres and in the right superior longitudinal fasciculus/anterior segment of arcuate fasciculus (p < .05, TFCE-corrected) after controlling for age, gender and GDS non-apathy. A trend association was observed in the right posterior corona radiata and corticospinal tract/internal capsule, and bilateral forceps minor (p < .065, TFCE-corrected). In conclusion, in aMCI, severity of apathy is associated with aberrant white matter integrity in widely distributed pathways, within and between hemispheres.

Out-of-step: brain-heart desynchronization in anxiety disorders.

Imaging studies in anxiety disorders (AD) show abnormal functional connectivity primarily in the salience network (SN), somatomotor network (SMN), and default mode network (DMN). However, it is not clear how precisely these network changes occur including their relation to psychopathological symptoms. Here, we show that the functional networks affected in AD overlap with cortical regions that receive visceral inputs (the so-called central/visceral autonomic network). Focusing on cardiac afferents, we suggest that network changes in AD may be due to reduced phase synchronization between ongoing neural and cardiac activity. This neuro-cardiac desynchronization occurs due to the abnormal phase resetting of neural activity at the onset of each heartbeat, as measured by a lower intertrial coherence and heartbeat-evoked potential. Biochemically, cardiac afferents reach subcortical serotonergic raphe nuclei and noradrenergic locus coeruleus (among others) which, in turn, are known to reciprocally modulate the DMN and SMN/SN on the cortical level. Consistent with the network changes in AD, decreases in serotonergic and noradrenergic activity are known to increase connectivity in both SMN and SN while, at the same time, they decrease DMN connectivity. SMN and SN increases, in turn, lead to increased emotional arousal/anxiety and bodily awareness whereas decreased DMN connectivity leads to an unstable sense-of-self in AD. Finally, we integrate our proposal with interoceptive predictive processing models suggesting neuro-cardiac desynchronization as a mechanism for "noisy" bottom-up information leading to a persistently uncertain bodily state in top-down models. In sum, integrating theories on active interference and hyperarousal, we propose a precise neuro-cardiac and biochemically -driven mechanisms for key psychopathological symptoms of AD.

Rest-task modulation of fMRI-derived global signal topography is mediated by transient coactivation patterns.

Recent resting-state functional MRI (fMRI) studies have revealed that the global signal (GS) exhibits a nonuniform spatial distribution across the gray matter. Whether this topography is informative remains largely unknown. We therefore tested rest-task modulation of GS topography by analyzing static GS correlation and dynamic coactivation patterns in a large sample of an fMRI dataset (n = 837) from the Human Connectome Project. The GS topography in the resting state and in seven different tasks was first measured by correlating the GS with the local time series (GSCORR). In the resting state, high GSCORR was observed mainly in the primary sensory and motor regions, whereas low GSCORR was seen in the association brain areas. This pattern changed during the seven tasks, with mainly decreased GSCORR in sensorimotor cortex. Importantly, this rest-task modulation of GSCORR could be traced to transient coactivation patterns at the peak period of GS (GS-peak). By comparing the topography of GSCORR and respiration effects, we observed that the topography of respiration mimicked the topography of GS in the resting state, whereas both differed during the task states; because of such partial dissociation, we assume that GSCORR could not be equated with a respiration effect. Finally, rest-task modulation of GS topography could not be exclusively explained by other sources of physiological noise. Together, we here demonstrate the informative nature of GS topography by showing its rest-task modulation, the underlying dynamic coactivation patterns, and its partial dissociation from respiration effects during task states.

Functional network topology associated with apathy in Alzheimer's disease.

BACKGROUND: Apathy, a common neuropsychiatric (NPS) in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD), is associated with structural and metabolic brain changes. However, functional connectivity changes across the brain in association with apathy remain unclear. In this study, graph theoretical measures of integration and segregation from resting state functional connectivity in MCI and AD patients with low depression scores, and healthy controls. METHODS: In MCI and AD patients with low depression scores, graph theoretical measures of integration and segregation were derived from resting state functional connectivity in patients, which were compared between those with apathy (NPS_A, n = 21) to those without NPS (NPS_None, n = 28) and those with NPS other than apathy (NPS_NA, n = 38). Additionally, the same measures were compared between AD patients and healthy controls (amyloid uptake below threshold levels). RESULTS: Altered whole brain global efficiency and reduced local efficiency were found in NPS_A compared to NPS_None and NPS_NA. In similar contrasts, apathy was associated with increased participation coefficient in the frontoparietal and cingulo-opercular template-based networks. A study-specific network definition also showed similar results. In comparison, AD patients showed higher modularity compared to controls at the whole brain level and higher participation coefficient in the ventral attention network. LIMITATIONS: The severity and dimensions of apathy were not assessed. CONCLUSIONS: Loss of segregation in the frontoparietal and cingulo-opercular network, which are involved in the control of goal-directed behavior, was associated with apathy in MCI/AD. The results also suggest that network-level changes in AD patients may underlie specific NPS.

Abnormal Functional Relationship of Sensorimotor Network With Neurotransmitter-Related Nuclei via Subcortical-Cortical Loops in Manic and Depressive Phases of Bipolar Disorder.

OBJECTIVE: Manic and depressive phases of bipolar disorder (BD) show opposite psychomotor symptoms. Neuronally, these may depend on altered relationships between sensorimotor network (SMN) and subcortical structures. The study aimed to investigate the functional relationships of SMN with substantia nigra (SN) and raphe nuclei (RN) via subcortical-cortical loops, and their alteration in bipolar mania and depression, as characterized by psychomotor excitation and inhibition. METHOD: In this resting-state functional magnetic resonance imaging (fMRI) study on healthy (n = 67) and BD patients (n = 100), (1) functional connectivity (FC) between thalamus and SMN was calculated and correlated with FC from SN or RN to basal ganglia (BG)/thalamus in healthy; (2) using an a-priori-driven approach, thalamus-SMN FC, SN-BG/thalamus FC, and RN-BG/thalamus FC were compared between healthy and BD, focusing on manic (n = 34) and inhibited depressed (n = 21) patients. RESULTS: (1) In healthy, the thalamus-SMN FC showed a quadratic correlation with SN-BG/thalamus FC and a linear negative correlation with RN-BG/thalamus FC. Accordingly, the SN-related FC appears to enable the thalamus-SMN coupling, while the RN-related FC affects it favoring anti-correlation. (2) In BD, mania showed an increase in thalamus-SMN FC toward positive values (ie, thalamus-SMN abnormal coupling) paralleled by reduction of RN-BG/thalamus FC. By contrast, inhibited depression showed a decrease in thalamus-SMN FC toward around-zero values (ie, thalamus-SMN disconnection) paralleled by reduction of SN-BG/thalamus FC (and RN-BG/thalamus FC). The results were replicated in independent HC and BD datasets. CONCLUSIONS: These findings suggest an abnormal relationship of SMN with neurotransmitters-related areas via subcortical-cortical loops in mania and inhibited depression, finally resulting in psychomotor alterations.

Personalized Multimodal Demarcation of Peritumoral Tissue in Glioma.

PURPOSE: Gliomas are life-threatening brain tumors, and the extent of surgical resection is one of the strongest influences on survival rate. However, the proper distinction of infiltrated tissue remains elusive. The aim of this study was to use multimodal analyses to demarcate peritumoral tissue (PT) from tumoral (TT) and healthy tissue (HT). METHODS: A total of 40 patients with histologically confirmed glioma were recruited. We analyzed resting-state functional magnetic resonance imaging (rs-fMRI) using the voxel-based mean blood-oxygen-level-dependent (BOLD) signal and the corresponding structural MRI (s-MRI) alongside RNA sequencing, whole-exome sequencing, and histology results of biopsy samples obtained from PT, HT, and TT. RESULTS: We demarcated a functionally defined PT area where the mean BOLD signal gradually decreased near the edge of the tumor and extended beyond the TT borders (as defined by s-MRI), which was confirmed on a case-by-case basis. Correspondingly, genetic analyses showed a gene expression pattern and mutational landscape of the PT that were distinct from that seen in HT and TT. The genetic characterization of PT relative to HT and TT converged with the MRI-defined PT zones. This was confirmed in three individual cases after additional histologic analysis. A wider PT was associated with a longer progression-free survival, which suggests PT might act as an intermediate area between TT and HT. CONCLUSION: Combined multimodal imaging and genetic analyses can allow for an objective demarcation of the PT in glioma and a robust classification of the degree of infiltration of the PT. These findings could help improve both neurosurgical resection and radio-oncologic therapy.

"Average is good, extremes are bad" - Non-linear inverted U-shaped relationship between neural mechanisms and functionality of mental features.

Traditionally, studies emphasize differences in neural measures between pathological and healthy groups, assuming a binary distinction between the groups, and a linear relationship between neural measures and symptoms. Here, we present four examples that show a continuous relation across the divide of normal and pathological states between neural measures and mental functions. This relation can be characterized by a non-linear inverted-U shaped curve. Along this curve, mid-range or average expression of a neural measure is associated with optimal function of a mental feature (in healthy states), whereas extreme expression, either high or low, is associated with sub-optimal function, and occurs in different neural disorders. Neural expression between the optimal or intermediate and pathological or extreme values is associated with sub-optimal function and at-risk mental states. Thus, this model of neuro-mental relationship can be summarized as "average is good, extremes are bad". By focussing on neuro-mental relationships, this model can facilitate the transition of psychiatry from a categorical to a dimensional and individualized approach needed in the era of precision medicine.