Gene expression variance in hippocampal tissue of temporal lobe epilepsy patients corresponds to differential memory performance.

Temporal lobe epilepsy (TLE) is a severe brain disorder affecting particularly young adults. TLE is frequently associated with memory deterioration and neuronal damage of the hippocampal formation. It thereby reveals striking parallels to neurodegenerative disorders including Alzheimer's disease (AD). TLE patients differ with respect to their cognitive performance, but currently little is known about relevant molecular-genetic factors. Here, we correlated differential memory performance of pharmacoresistant TLE patients undergoing neurosurgery for seizure control with in-vitro findings of their hippocampal tissues. We analyzed mRNA transcripts and subsequently promoter variants specifically altered in brain tissue of individuals with 'very severe' memory impairment. TLE patients (n=79) were stratified according to preoperative memory impairment using an established four-tiered grading system ranging from 'average' to 'very severely'. Multimodal cluster analyses revealed molecules specifically associated with synaptic function and abundantly expressed in TLE patients with very impaired memory performance. In a subsequent promoter analysis, we found the single nucleotide polymorphism rs744373 C-allele to be associated with high mRNA levels of bridging integrator 1 (BIN1)/Amphiphysin 2, i.e. a major component of the endocytotic machinery and located in a crucial genetic AD risk locus. Using in vitro luciferase transfection assays, we found that BIN1 promoter activation is genotype dependent and strongly increased by reduced binding of the transcriptional repressor TGIF. Our data indicate that poor memory performance in patients with TLE strongly corresponds to distinctly altered neuronal transcript signatures, which - as demonstrated for BIN1 - can correlate with a particular allelic promoter variant. Our data suggest aberrant transcriptional signaling to significantly impact synaptic dynamics in TLE resulting in impaired memory performance and may serve as basis for future therapy development of this severe comorbidity.

Characteristic functional connectome related to Post-COVID-19 syndrome.

Post-COVID-19 syndrome is a serious complication following SARS-CoV-2 infection, characterized primarily by fatigue and cognitive complaints. Although first metabolic and structural imaging alterations in Post-COVID-19 syndrome have been identified, their functional consequences remain unknown. Thus, we explored the impact of Post-COVID-19 syndrome on the functional connectome of the brain providing a deeper understanding of pathophysiological mechanisms. In a cross-sectional observational study, resting-state functional magnetic resonance imaging data of 66 patients with Post-COVID-19 syndrome after mild infection (mean age 42.3 years, 57 female) and 57 healthy controls (mean age 42.1 years, 38 female) with a mean time of seven months after acute COVID-19 were analysed using a graph theoretical approach. Network features were quantified using measures including mean distance, nodal degree, betweenness and Katz centrality, and compared between both groups. Graph measures were correlated with clinical measures quantifying fatigue, cognitive function, affective symptoms and sleep disturbances. Alterations were mainly found in the brainstem, olfactory cortex, cingulate cortex, thalamus and cerebellum on average seven months after SARS-CoV-2 infection. Additionally, strong correlations between fatigue severity, cognitive functioning and daytime sleepiness from clinical scales and graph measures were observed. Our study confirms functional relevance of brain imaging changes in Post-COVID-19 syndrome as mediating factors for persistent symptoms and improves our pathophysiological understanding.

Structural brain changes in patients with post-COVID fatigue: a prospective observational study.

Background: Post-COVID syndrome is a severe long-term complication of COVID-19. Although fatigue and cognitive complaints are the most prominent symptoms, it is unclear whether they have structural correlates in the brain. We therefore explored the clinical characteristics of post-COVID fatigue, describe associated structural imaging changes, and determine what influences fatigue severity. Methods: We prospectively recruited 50 patients from neurological post-COVID outpatient clinics (age 18-69 years, 39f/8m) and matched non-COVID healthy controls between April 15 and December 31, 2021. Assessments included diffusion and volumetric MR imaging, neuropsychiatric, and cognitive testing. At 7.5 months (median, IQR 6.5-9.2) after the acute SARS-CoV-2 infection, moderate or severe fatigue was identified in 47/50 patients with post-COVID syndrome who were included in the analyses. As a clinical control group, we included 47 matched multiple sclerosis patients with fatigue. Findings: Our diffusion imaging analyses revealed aberrant fractional anisotropy of the thalamus. Diffusion markers correlated with fatigue severity, such as physical fatigue, fatigue-related impairment in everyday life (Bell score) and daytime sleepiness. Moreover, we observed shape deformations and decreased volumes of the left thalamus, putamen, and pallidum. These overlapped with the more extensive subcortical changes in MS and were associated with impaired short-term memory. While fatigue severity was not related to COVID-19 disease courses (6/47 hospitalised, 2/47 with ICU treatment), post-acute sleep quality and depressiveness emerged as associated factors and were accompanied by increased levels of anxiety and daytime sleepiness. Interpretation: Characteristic structural imaging changes of the thalamus and basal ganglia underlie the persistent fatigue experienced by patients with post-COVID syndrome. Evidence for pathological changes to these subcortical motor and cognitive hubs provides a key to the understanding of post-COVID fatigue and related neuropsychiatric complications. Funding: Deutsche Forschungsgemeinschaft (DFG) and German Ministry of Education and Research (BMBF).

Long COVID-19: Objectifying most self-reported neurological symptoms.

OBJECTIVES: We aimed to objectify and compare persisting self-reported symptoms in initially hospitalized and non-hospitalized patients after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by applying clinical standardized measures. METHODS: We conducted a cross-sectional study of adult patients with confirmed SARS-CoV-2 infection including medical history, neurological examination, blood markers, neuropsychological testing, patient-reported outcome measures (PROMs), and brain magnetic resonance imaging (MRI). RESULTS: Fifty patients with persisting symptoms for at least 4 weeks were included and classified by initial hospitalization status. Median time from SARS-CoV-2 detection to investigation was 29.3 weeks (range 3.3-57.9). Although individual cognitive performance was generally within the normative range in both groups, mostly mild deficits were found in attention, executive functions, and memory. Hospitalized patients performed worse in global cognition, logical reasoning, and processes of verbal memory. In both groups, fatigue severity was associated with reduced performance in attention and psychomotor speed tasks (rs = -0.40, p < 0.05) and reduced quality of life (EQ5D, rs = 0.57, p < 0.001) and with more persisting symptoms (median 3 vs. 6, p < 0.01). PROMs identified fatigue, reduced sleep quality, and increased anxiety and depression in both groups but more pronounced in non-hospitalized patients. Brain MRI revealed microbleeds exclusively in hospitalized patients (n = 5). INTERPRETATION: Regardless of initial COVID-19 severity, an individuals' mental and physical health can be severely impaired in the long-term limitedly objectified by clinical standard diagnostic with abnormalities primarily found in hospitalized patients. This needs to be considered when planning rehabilitation therapies and should give rise to new biomarker research.

Neurological symptoms in COVID-19: a cross-sectional monocentric study of hospitalized patients.

BACKGROUND: The SARS-Coronavirus-2 (SARS-CoV-2) invades the respiratory system, causing acute and sometimes severe pulmonary symptoms, but turned out to also act multisystematically with substantial impact on the brain. A growing number of studies suggests a diverse spectrum of neurological manifestations. To investigate the spectrum of symptoms, we here describe the neurological manifestations and complications of patients with proven SARS-CoV-2 infection who have been hospitalized at the RWTH University Hospital Aachen, Germany. METHODS: Between March and September 2020, we evaluated common symptoms, clinical characteristics, laboratory (including cerebrospinal fluid (CSF) analysis), radiological, and electroencephalography (EEG) data from 53 patients admitted with a positive SARS-CoV-2 polymerase chain reaction (PCR). We used the Montreal Cognitive Assessment Test (MoCA) to screen for cognitive impairment, when feasible. We compared critically ill and non-critically ill patients categorized according to the presence of Acute Respiratory Distress Syndrome (ARDS). RESULTS: Major clinical neurological features of hospitalized COVID-19 patients were coordination deficits (74%), cognitive impairment (61.5%), paresis (47%), abnormal reflex status (45%), sensory abnormalities (45%), general muscle weakness and pain (32%), hyposmia (26%), and headache (21%). Patients with ARDS were more severely affected than non-ADRS patients. 29.6% of patients with ARDS presented with subarachnoid bleedings, and 11.1% showed ischemic stroke associated with SARS-CoV-2 infection. Cognitive deficits mainly affected executive functions, attention, language, and delayed memory recall. We obtained cerebrospinal fluid (CSF) by lumbar puncture in nine of the 53 patients, none of which had a positive SARS-CoV-2 PCR. CONCLUSIONS: In line with previous findings, our results provide evidence for a range of SARS-CoV-2-associated neurological manifestations. 26% of patients reported hyposmia, emphasizing the neuro-invasive potential of SARS-CoV-2, which can enter the olfactory bulb. It can therefore be speculated that neurological manifestations may be caused by direct invasion of the virus in the CNS; however, PCR did not reveal positive intrathecal SARS-CoV-2. Therefore, we hypothesize it is more likely that the para-infectious severe pro-inflammatory impact of COVID-19 is responsible for the neurological deficits including cognitive impairment. Future studies with comprehensive longitudinal assessment of neurological deficits are required to determine potential long-term complications of COVID-19.

Exome sequencing in syndromic brain malformations identifies novel mutations in ACTB, and SLC9A6, and suggests BAZ1A as a new candidate gene.

BACKGROUND: Syndromic brain malformations comprise a large group of anomalies with a birth prevalence of about 1 in 1,000 live births. Their etiological factors remain largely unknown. To identify causative mutations, we used whole-exome sequencing (WES) in aborted fetuses and children with syndromic brain malformations in which chromosomal microarray analysis was previously unremarkable. METHODS: WES analysis was applied in eight case-parent trios, six aborted fetuses, and two children. RESULTS: WES identified a novel de novo mutation (p.Gly268Arg) in ACTB (Baraitser-Winter syndrome-1), a homozygous stop mutation (p.R2442*) in ASPM (primary microcephaly type 5), and a novel hemizygous X-chromosomal mutation (p.I250V) in SLC9A6 (X-linked syndromic mentaly retardation, Christianson type). Furthermore, WES identified a de novo mutation (p.Arg1093Gln) in BAZ1A. This mutation was previously reported in only one allele in 121.362 alleles tested (dbSNP build 147). BAZ1A has been associated with neurodevelopmental impairment and dysregulation of several pathways including vitamin D metabolism. Here, serum vitamin-D (25-(OH)D) levels were insufficient and gene expression comparison between the child and her parents identified 27 differentially expressed genes. Of note, 10 out of these 27 genes are associated to cytoskeleton, integrin and synaptic related pathways, pinpointing to the relevance of BAZ1A in neural development. In situ hybridization in mouse embryos between E10.5 and E13.5 detected Baz1a expression in the central and peripheral nervous system. CONCLUSION: In syndromic brain malformations, WES is likely to identify causative mutations when chromosomal microarray analysis is unremarkable. Our findings suggest BAZ1A as a possible new candidate gene.