Clinical and Translational Neuroscience

Objective: Alzheimer’s disease (AD) and other forms of dementia are a heterogeneous group of neurodegenerative diseases characterized by progressive cognitive decline. Differential diagnosis between AD and other dementias is crucial for choosing the optimal treatment strategy. Currently, cerebrospinal fluid (CSF) analysis remains the most accurate diagnostic method, but its invasiveness limits its use. In this regard, the search for reliable biomarkers in the blood is an urgent task. Methods: The study included 31 dementia patients (23 women and 8 men) diagnosed via interdisciplinary consultations and neuropsychological testing (MMSE ≤ 24). CSF and blood plasma samples were collected and analyzed using Luminex technology. Biomarker concentrations were measured, and statistical analyses (ANOVA, Kruskal–Wallis, and Pearson correlation) were performed to compare groups and assess correlations. Results: Levels of Aβ40 and Aβ42 in CSF were significantly lower in patients with AD compared with non-AD dementia (p = 0.02 and p < 0.001, respectively). The Aβ42/40 ratio in CSF was higher in patients with non-AD dementia (p = 0.048). The concentration of Aβ42 in blood plasma was increased in patients with AD (p = 0.001). Positive correlations were found between Aβ42 in CSF and TDP-43 in plasma in non-AD dementia (r = 0.97, p < 0.001), as well as between neurogranin and TDP-43 in plasma in AD (r = 0.845, p < 0.001). Conclusions: The study demonstrates the potential of blood biomarkers, in particular Aβ42, for the differential diagnosis of AD and other forms of dementia. The discovered correlations between CSF and plasma biomarkers deepen the understanding of neurodegenerative processes and contribute to the development of noninvasive diagnostic methods.

Down Syndrome Regression Disorder (DSRD) is a rare but severe neuropsychiatric condition characterized by abrupt loss of speech, autonomy, and cognitive abilities in individuals with Down syndrome, often associated with immune dysregulation and gut–brain axis dysfunction. We report the case of an 11-year-old girl with Down syndrome who developed developmental regression at age five, in temporal proximity to a family transition (the birth of a younger sibling), with loss of continence, language, and comprehension, alongside persistent behavioral agitation and gastrointestinal symptoms. Laboratory assessment revealed Giardia duodenalis infection, elevated fecal calprotectin and secretory IgA, and microbial imbalance with overgrowth of Streptococcus anginosus and S. sobrinus. The patient received a single oral dose of tinidazole (2 g), daily folinic acid (1 mg/kg), and a 90-day course of transcranial and abdominal photobiomodulation (PBM) (1064 nm, 10 min per site). Post-treatment, stool analysis showed normalized inflammation markers and restoration of beneficial bacterial genera (Bacteroides, Bifidobacterium, Lactobacillus) with absence of Enterococcus growth. Behaviorally, she exhibited marked recovery: CARS-2-QPC decreased from 106 to 91, ABC from 63 to 31, and ATEC from 62 to 57, alongside regained continence, speech, and fine-motor coordination. These outcomes suggest that abdominal and transcranial PBM, by modulating mitochondrial metabolism, mucosal immunity, and microbiota composition, may facilitate systemic and neurobehavioral recovery in DSRD. This translational case supports further investigation of PBM as a non-invasive, multimodal therapy for neuroimmune regression in genetic and developmental disorders including validation through future randomized controlled clinical trials.

The high attrition rates in glioblastoma (GB) therapeutic development stem largely from preclinical models that fail to adequately recapitulate the dynamic tumor–host ecosystem. Unlike previous reviews that characterize glioma cell lines in isolation, this article integrates tumor biology with the distinct neuro-immune–endocrine landscapes of major laboratory rat strains. We critically evaluate standard rat malignant glioma cell lines (C6, F98, RG2, 9L) alongside transplantable tissue models (GB 101.8, GB 15/47), which offer enhanced translational relevance, demonstrating that the predictive value of any model is contingent upon the specific “glioma model and host strain” pairing and the individual physiological characteristics of the host. We provide evidence that strain-specific hypothalamic–pituitary–adrenal (HPA) axis reactivity (e.g., hyper-reactive Fischer 344 versus normo-reactive Wistar) acts as a decisive, yet often overlooked, modulator of the tumor microenvironment and therapeutic response. The review delineates the utility and limitations of these models, specifically addressing the MHC incompatibilities of the widely used C6 model in immunotherapy research, while contrasting it with the immune-evasive phenotypes of RG2 and the GB 101.8 tissue model. Furthermore, we highlight the superiority of tissue transplants in preserving cellular polyclonality and diffuse infiltration patterns compared to the circumscribed growth often observed in cell line-derived tumors. Consequently, we propose a strategic selection paradigm wherein immunogenic models serve as bioindicators of host immunocompetence, while invasive, non-immunogenic systems (F98, RG2, and GB 101.8) are utilized to investigate therapeutic resistance and systemic host-tumor interactions.