A Residual Marker of Cognitive Reserve Is Associated with Resting-State Intrinsic Functional Connectivity Along the Alzheimer's Disease Continuum.

BACKGROUND: Cognitive reserve (CR) explains inter-individual differences in the impact of the neurodegenerative burden on cognitive functioning. A residual model was proposed to estimate CR more accurately than previous measures. However, associations between residual CR markers (CRM) and functional connectivity (FC) remain unexplored. OBJECTIVE: To explore the associations between the CRM and intrinsic network connectivity (INC) in resting-state networks along the neuropathological-continuum of Alzheimer's disease (ADN). METHODS: Three hundred eighteen participants from the DELCODE cohort were stratified using cerebrospinal fluid biomarkers according to the A(myloid-ß)/T(au)/N(eurodegeneration) classification. CRM was calculated utilizing residuals obtained from a multilinear regression model predicting cognition from markers of disease burden. Using an independent component analysis in resting-state fMRI data, we measured INC of resting-state networks, i.e., default mode network (DMN), frontoparietal network (FPN), salience network (SAL), and dorsal attention network. The associations of INC with a composite memory score and CRM and the associations of CRM with the seed-to-voxel functional connectivity of memory-related were tested in general linear models. RESULTS: CRM was positively associated with INC in the DMN in the entire cohort. The A+T+N+ group revealed an anti-correlation between the SAL and the DMN. Furthermore, CRM was positively associated with anti-correlation between memory-related regions in FPN and DMN in ADN and A+T/N+. CONCLUSION: Our results provide evidence that INC is associated with CRM in ADN defined as participants with amyloid pathology with or without cognitive symptoms, suggesting that the neural correlates of CR are mirrored in network FC in resting-state.

Additive value of [18F]PI-2620 perfusion imaging in progressive supranuclear palsy and corticobasal syndrome.

PURPOSE: Early after [18F]PI-2620 PET tracer administration, perfusion imaging has potential for regional assessment of neuronal injury in neurodegenerative diseases. This is while standard late-phase [18F]PI-2620 tau-PET is able to discriminate the 4-repeat tauopathies progressive supranuclear palsy and corticobasal syndrome (4RTs) from disease controls and healthy controls. Here, we investigated whether early-phase [18F]PI-2620 PET has an additive value for biomarker based evaluation of 4RTs. METHODS: Seventy-eight patients with 4RTs (71 ± 7 years, 39 female), 79 patients with other neurodegenerative diseases (67 ± 12 years, 35 female) and twelve age-matched controls (69 ± 8 years, 8 female) underwent dynamic (0-60 min) [18F]PI-2620 PET imaging. Regional perfusion (0.5-2.5 min p.i.) and tau load (20-40 min p.i.) were measured in 246 predefined brain regions [standardized-uptake-value ratios (SUVr), cerebellar reference]. Regional SUVr were compared between 4RTs and controls by an ANOVA including false-discovery-rate (FDR, p < 0.01) correction. Hypoperfusion in resulting 4RT target regions was evaluated at the patient level in all patients (mean value - 2SD threshold). Additionally, perfusion and tau pattern expression levels were explored regarding their potential discriminatory value of 4RTs against other neurodegenerative disorders, including validation in an independent external dataset (n = 37), and correlated with clinical severity in 4RTs (PSP rating scale, MoCA, activities of daily living). RESULTS: Patients with 4RTs had significant hypoperfusion in 21/246 brain regions, most dominant in thalamus, caudate nucleus, and anterior cingulate cortex, fitting to the topology of the 4RT disease spectrum. However, single region hypoperfusion was not specific regarding the discrimination of patients with 4RTs against patients with other neurodegenerative diseases. In contrast, perfusion pattern expression showed promise for discrimination of patients with 4RTs from other neurodegenerative diseases (AUC: 0.850). Discrimination by the combined perfusion-tau pattern expression (AUC: 0.903) exceeded that of the sole tau pattern expression (AUC: 0.864) and the discriminatory power of the combined perfusion-tau pattern expression was replicated in the external dataset (AUC: 0.917). Perfusion but not tau pattern expression was associated with PSP rating scale (R = 0.402; p = 0.0012) and activities of daily living (R = - 0.431; p = 0.0005). CONCLUSION: [18F]PI-2620 perfusion imaging mirrors known topology of regional hypoperfusion in 4RTs. Single region hypoperfusion is not specific for 4RTs, but perfusion pattern expression may provide an additive value for the discrimination of 4RTs from other neurodegenerative diseases and correlates closer with clinical severity than tau pattern expression.

Anodal transcranial direct current stimulation sustainably increases EEG alpha activity in patients with schizophrenia.

AIMS: Transcranial direct current stimulation (tDCS) applied to the prefrontal cortex has been frequently used to elicit behavioral changes in patients with schizophrenia. However, the interaction between prefrontal tDCS and electrophysiological changes remains largely uncharted. The present study aimed to investigate cortical electrophysiological changes induced by tDCS in frontal areas by means of repeated electroencephalography (EEG) in patients with schizophrenia. METHODS: In total, 20 patients with schizophrenia received 13 minutes of anodal tDCS (1 mA) applied to the left dorsolateral prefrontal cortex (DLPFC). Repeated resting EEG was recorded before (once) and following (at five follow-up time-bins) tDCS to trace post-tDCS effects. We used sLORETA for source reconstruction to preserve the localization of brain signals with a low variance and to analyze frequency changes. RESULTS: We observed significant changes after the stimulation in areas highly connected with the stimulated DLPFC areas. The alpha 1 (8.5-10.0 Hz) activity showed a highly significant, long-lasting, increase for up to 1 hour after the stimulation in the postcentral gyrus (Brodmann area 2, 3, and 40). Significant yet unstable changes were also seen in the alpha-2 frequency band precentral at 10 minutes, in the beta-1 frequency band occipital at 20 minutes, and in the beta-3 frequency band temporal at 40 minutes. CONCLUSION: We were able to show that anodal tDCS can induce stable EEG changes in patients with schizophrenia. The results underline the potential of tDCS to induce long-lasting neurophysiological changes in patients with schizophrenia showing the possibility to induce brain excitability changes in this population.

Effects of high-frequency prefrontal rTMS on heart frequency rates and blood pressure in schizophrenia.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is a safe non-invasive neuromodulation technique used for the treatment of various neuropsychiatric disorders. The effect of rTMS applied to the cortex on autonomic functions has not been studied in detail in patient cohorts, yet patients who receive rTMS may have disease-associated impairments in the autonomic system and may receive medication that may pronounce autonomic dysfunctions. METHODS: Using data from the 'rTMS for the Treatment of Negative Symptoms in Schizophrenia' (RESIS) trial we evaluated the effect of rTMS applied to the left dorsolateral prefrontal cortex (DLPFC) on autonomic nervous system-related parameters such as blood pressure (BP) and heart rate (HR) in both reclining and standing postures from screening up to 105 days after intervention among patients with schizophrenia. RESULTS: 157 patients received either active (n = 76) or sham (n = 81) rTMS treatment. Apart from gender no significant group differences were observed. During intervention, Linear Mixed Model (LMM) analyses showed no significant time × group interactions nor time effects for any of the variables (all p > 0.055). During the whole trial beside a significant time × group interaction for diastolic BP (p = 0.017) in the standing posture, no significant time × group interactions for other variables (all p > 0.140) were found. CONCLUSION: These secondary analyses of the largest available rTMS trial on the treatment of negative symptoms in schizophrenia did not show a significant effect of active rTMS compared to sham rTMS on heart rate or blood pressure, neither during the intervention period nor during the follow-up period.

Cortical [18 F]PI-2620 Binding Differentiates Corticobasal Syndrome Subtypes.

BACKGROUND: Corticobasal syndrome is associated with cerebral protein aggregates composed of 4-repeat (~50% of cases) or mixed 3-repeat/4-repeat tau isoforms (~25% of cases) or nontauopathies (~25% of cases). OBJECTIVES: The aim of this single-center study was to investigate the diagnostic value of the tau PET-ligand [18 F]PI-2620 in patients with corticobasal syndrome. METHODS: Forty-five patients (71.5 ± 7.6 years) with corticobasal syndrome and 14 age-matched healthy controls underwent [18 F]PI-2620-PET. Beta-amyloid status was determined by cerebral ß-amyloid PET and/or CSF analysis. Subcortical and cortical [18 F]PI-2620 binding was quantitatively and visually compared between ß-amyloid-positive and -negative patients and controls. Regional [18 F]PI-2620 binding was correlated with clinical and demographic data. RESULTS: Twenty-four percent (11 of 45) were ß-amyloid-positive. Significantly elevated [18 F]PI-2620 distribution volume ratios were observed in both ß-amyloid-positive and ß-amyloid-negative patients versus controls in the dorsolateral prefrontal cortex and basal ganglia. Cortical [18 F]PI-2620 PET positivity was distinctly higher in ß-amyloid-positive compared with ß-amyloid-negative patients with pronounced involvement of the dorsolateral prefrontal cortex. Semiquantitative analysis of [18 F]PI-2620 PET revealed a sensitivity of 91% for ß-amyloid-positive and of 65% for ß-amyloid-negative cases, which is in excellent agreement with prior clinicopathological data. Regardless of ß-amyloid status, hemispheric lateralization of [18 F]PI-2620 signal reflected contralateral predominance of clinical disease severity. CONCLUSIONS: Our data indicate a value of [18 F]PI-2620 for evaluating corticobasal syndrome, providing quantitatively and regionally distinct signals in ß-amyloid-positive as well as ß-amyloid-negative corticobasal syndrome. In corticobasal syndrome, [18 F]PI-2620 may potentially serve for a differential diagnosis and for monitoring disease progression. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

tDCS for auditory verbal hallucinations in a case of schizophrenia and left frontal lesion: efield simulation and clinical results.

Transcranial direct current stimulation (tDCS) has been explored for treatment of several neuropsychiatric disorders. For tDCS use in structural brain lesions there is some evidence from motor stroke rehabilitation and post-stroke depression. Here we report the application of tDCS in a woman previously diagnosed with schizophrenia presenting refractory auditory verbal hallucinations and left prefrontal tissue lesion. Treatment with 20 left fronto-temporal tDCS had no effect on psychiatric symptoms and neuropsychological evaluation. An ex-post electric field simulation and calculation of dorsolateral prefrontal cortex activation showed lower activation in this patient compared to a matched non-lesioned schizophrenia, and healthy control brain.