SARS-CoV-2's brain impact: revealing cortical and cerebellar differences via cluster analysis in COVID-19 recovered patients.

BACKGROUND: COVID-19 is a disease known for its neurological involvement. SARS-CoV-2 infection triggers neuroinflammation, which could significantly contribute to the development of long-term neurological symptoms and structural alterations in the gray matter. However, the existence of a consistent pattern of cerebral atrophy remains uncertain. OBJECTIVE: Our study aimed to identify patterns of brain involvement in recovered COVID-19 patients and explore potential relationships with clinical variables during hospitalization. METHODOLOGY: In this study, we included 39 recovered patients and 39 controls from a pre-pandemic database to ensure their non-exposure to the virus. We obtained clinical data of the patients during hospitalization, and 3 months later; in addition we obtained T1-weighted magnetic resonance images and performed standard screening cognitive tests. RESULTS: We identified two groups of recovered patients based on a cluster analysis of the significant cortical thickness differences between patients and controls. Group 1 displayed significant cortical thickness differences in specific cerebral regions, while Group 2 exhibited significant differences in the cerebellum, though neither group showed cognitive deterioration at the group level. Notably, Group 1 showed a tendency of higher D-dimer values during hospitalization compared to Group 2, prior to p-value correction. CONCLUSION: This data-driven division into two groups based on the brain structural differences, and the possible link to D-dimer values may provide insights into the underlying mechanisms of SARS-COV-2 neurological disruption and its impact on the brain during and after recovery from the disease.

Assessment of visuospatial functions in post-Covid 19 patients: Beyond the traditional paradigm.

Several studies indicate that some cognitive changes occur after COVID-19. Visuospatial alterations have been reported in 24-40 %. These alterations may be useful as early biomarkers of neurodegenerative disease. Thus, we can emphasize the importance of visuospatial processes in cognition through quantitative and qualitative analysis of performance on the Clock Test (CDT) and the Rey-Osterrieth Complex Figure (FCRO). Our objective was to describe the performance of post COVID 19 patients in visuospatial tests, with different degrees of respiratory impairment and to perform a qualitative analysis of the performance to check its relationship with alterations in attention and executive functions. This will allow highlighting the executive component of the performance of the CDT and ROCF and differentiate patients with possible cognitive impairment. 77 patients with SARS-CoV-2 infection were evaluated (3 months post-infection) with a complete neuropsychological battery and MRI. Overall, there is a significant difference between FCRO and CDT, with FCRO having only 9 % change and CDT having 51.9 % change. Regarding the correlations observed between groups (VM Inv, VM non I and non hospitalized) the highest correlations were observed between Boston with FCRO copy (r=0.497; p=0.001) and with FCRO memory (r=0.429; p=0.001). Comparing the performance between groups by severity, significant differences were observed only in the TMT A (13.706 p=0.001) and B (9.583 p=0.008) tests and in the phonological fluency letter A (13.445 p=0.001), we observed that the group of non-hospitalized patients had a better performance. Neuropsychological deficits often have a direct impact on daily life by affecting the ability to learn and adapt. Thus, a useful strategy for the neuropsychological characterization of post-COVID-19 patients is the qualitative analysis of visuospatial abilities in conjunction with executive functions that cannot be analyzed in isolation.

Relationship between APOE, PER2, PER3 and OX2R Genetic Variants and Neuropsychiatric Symptoms in Patients with Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by the presence of neuropsychiatric or behavioral and psychological symptoms of dementia (BPSD). BPSD have been associated with the APOE_ε4 allele, which is also the major genetic AD risk factor. Although the involvement of some circadian genes and orexin receptors in sleep and behavioral disorders has been studied in some psychiatric pathologies, including AD, there are no studies considering gene-gene interactions. The associations of one variant in PER2, two in PER3, two in OX2R and two in APOE were evaluated in 31 AD patients and 31 cognitively healthy subjects. Genotyping was performed using real-time PCR and capillary electrophoresis from blood samples. The allelic-genotypic frequencies of variants were calculated for the sample study. We explored associations between allelic variants with BPSD in AD patients based on the NPI, PHQ-9 and sleeping disorders questionnaires. Our results showed that the APOE_ε4 allele is an AD risk variant (p = 0.03). The remaining genetic variants did not reveal significant differences between patients and controls. The PER3_rs228697 variant showed a nine-fold increased risk for circadian rhythm sleep-wake disorders in Mexican AD patients, and our gene-gene interaction analysis identified a novel interaction between PERIOD and APOE gene variants. These findings need to be further confirmed in larger samples.

Las orexinas como biomarcadores para demencia tipo Alzheimer y relación con síntomas neuropsiquiátricos / Orexins as biomarkers for Alzheimer dementia and their relationship with neuropsychiatric symptoms

RESUMEN: Los biomarcadores más estudiados en la demencia tipo Alzheimer (DA) son los niveles elevados de Aβ42 y de proteína Tau en líquido cefalorraquídeo. Dada la complejidad de la sintomatología cognitiva y síntomas neuropsiquiátricos (SNP) de esta patología, algunos estudios recientes proponen sustancias como las orexinas, como blanco terapéutico de DA y SNP. El presente trabajo tiene como objetivo revisar publicaciones científicas recientes que hayan analizado la asociación entre orexinas, SNP y DA en humanos, algunos modelos animales y que hayan evaluado a las orexinas como posibles biomarcadores tanto para investigación como en el área clínica. En esta revisión también se describen los estudios que sugieren a las orexinas como un posible biomarcador en la DA, dada su relación con el Aβ42 y la proteína Tau, y otros estudios que las asocian con presencia de SNP, especialmente alteración del sueño. Se plantea la hipótesis de que la presencia de SNP en DA se asocia con las orexinas, debido a que este sistema influye en el funcionamiento hipotalámico y de forma indirecta en áreas cerebrales que regulan el comportamiento. Sin embargo, aún falta mayor investigación, principalmente de estudios longitudinales para conocer claramente la influencia de las orexinas en los SNP.

ABSTRACT The most studied biomarkers in Alzheimer's dementia (AD) are elevated levels of Aβ42 and Tau protein in cerebrospinal fluid. Given the complexity of the cognitive symptomatology and neuropsychiatric symptoms (NPS) of this pathology, some recent studies propose substances such as orexins as a therapeutic target for AD and NPS. The present work aims to review recent scientific publications that have analyzed the association between orexins, PNS and AD in humans. There are some animal models that have evaluated orexins as possible biomarkers both for research and in the clinical area. This review also describes studies that suggest orexins as possible biomarkers in AD, given their relationship with Aβ42 and Tau protein, and other studies that associate them with the presence of SNPs, especially sleep disturbance. It is hypothesized that the presence of SNPs in AD is associated with orexins, because this system influences hypothalamic functioning and indirectly in brain areas that regulate behavior. However, further research is still lacking, mainly longitudinal studies to clearly know the influence of orexins on SNPs.