👤 Dominik Paquet

Allostatic load (AL), an index of cumulative physiological dysregulation from chronic stress, may contribute to Alzheimer's disease (AD) pathophysiology by accelerating brain aging. Higher AL has been associated with AD-related biomarkers, suggesting a mechanistic connection. Lifestyle factors influence both AL and AD vulnerability, but their moderating role in AL-AD biomarker associations remains unclear. We included 111 cognitively unimpaired older adults from the baseline visit of the Age-Well trial. AL was computed as a composite score of 18 biomarkers spanning neuroendocrine, immune, metabolic, cardiovascular-respiratory, and anthropometric systems. Plasma biomarkers included amyloid beta (Aβ)42, Aβ40, phosphorylated-tau (p-tau231), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL). Physical activity, Mediterranean diet adherence, and cognitive activity were assessed using validated questionnaires. Multiple linear regressions tested associations between AL and (1) AD-related biomarkers and (2) lifestyle factors, as well as their interactions, controlling for age, sex, education, apolipoprotein E ε4 (APOE ε4) status, and glomerular filtration rate (GFR). Higher AL was associated with higher Aβ42/Aβ40 ratio ( Regular physical activity was associated with a weaker relationship between AL and early AD-related biomarkers in this cross-sectional sample. Longitudinal studies should confirm whether maintaining physical activity attenuates stress-related physiological dysregulation and reduces AD vulnerability. Show less

Anti-amyloid monoclonal antibodies, including lecanemab and donanemab, are now available for the treatment of Alzheimer's disease (AD). Defining real-world patient eligibility and identifying barriers to access are critical for their effective implementation in routine clinical practice. Retrospective observational multicenter study of patients who underwent CSF AD biomarker testing at Lariboisière Hospital (Paris, France) from 2023 to 2024, assessing lecanemab eligibility using CLARITY AD trial criteria and the French Memory Clinic Federation appropriate use recommendations (AURs) following EMA authorization. From a source population of 3075 patients, 676 underwent CSF testing, and 356 had biomarker-confirmed AD; 315 patients with MRI, APOE status, and MMSE data available (mean age 73.2 ± 8.1 years; 47.8% female; median MMSE 22 [IQR 19-26]) were screened. Using CLARITY AD trial criteria, 90 patients (28.6%) were eligible; low MMSE scores and MRI findings were the most frequent exclusion criteria. French AURs reduced eligibility to 75 patients (23.8%), excluding patients with a CSF A + T - profile and APOE ε4 homozygotes. Eligibility did not differ by age group. Eligibility rates from the entire source population equated to only 2.9% of patients using the CLARITY AD criteria and 2.4% using the French AURs. At follow-up, 34.5% of initially eligible patients no longer met the MMSE eligibility criteria. In specialized settings, lecanemab eligibility remained limited, highlighting the need for early AD diagnosis and efficient screening pathways. Show less

Current AT(N) stratification for Alzheimer's disease (AD) accounts for complex combinations of amyloid (A), tau proteinopathy (T) and neurodegeneration (N) signatures. Understanding the transition between these different stages is a major challenge, especially in view of the recent development of disease modifying therapy. This is an observational study, CSF levels of Tau, pTau181, pTau217, Aβ38/40/42, sAPPα/β, BACE1 and neurogranin were measured in the BALTAZAR cohort of cognitively impaired patients and in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Biomarkers levels were related to the AT(N) framework. (A) and (T) were defined in BALTAZAR with CSF Aβ42/40 ratio and pTau217 respectively, and in ADNI with amyloid and tau PET. (N) was defined using total CSF tau in both cohorts. As expected, CSF Aβ42 decreased progressively with the AD continuum going from the A-T-N- to the A + T + N + profile. On the other hand, Tau and pTau181 increased progressively with the disease. The final transition from A + T + N- to A + T + N + led to a sharp increase in Aβ38, Aβ42 and sAPP levels. Synaptic CSF biomarkers BACE1 and neurogranin, were lowest in the initial A + T-N- stage and increased with T + and N + . CSF pTau181 and total tau were closely related in both cohorts. The early transition to an A + phenotype (A + T-N-) primarily impacts synaptic function. The appearance of T + and then N + is associated with a significant and progressive increase in pathological Alzheimer's disease biomarkers. Our main finding is that CSF pTau181 is an indicator of N + rather than T + , and that N + is associated with elevated levels of BACE1 protein and beta-amyloid peptides. This increase may potentially fuel the amyloid cascade in a positive feedback loop. Overall, our data provide further insights into understanding the interconnected pathological processes of amyloid, tau, and neurodegeneration underlying Alzheimer's disease. Show less

Batten diseases (BDs) are a group of lysosomal storage disorders characterized by seizure, visual loss, and cognitive and motor deterioration. We discovered increased levels of globotriaosylceramide (Gb3) in cellular and murine models of CLN3 and CLN7 diseases and used fluorescent-conjugated bacterial toxins to label Gb3 to develop a cell-based high content imaging (HCI) screening assay for the repurposing of FDA-approved compounds able to reduce this accumulation within BD cells. We found that tamoxifen reduced the lysosomal accumulation of Gb3 in CLN3 and CLN7 cell models, including neuronal progenitor cells (NPCs) from CLN7 patient-derived induced pluripotent stem cells (iPSC). Here, tamoxifen exerts its action through a mechanism that involves activation of the transcription factor EB (TFEB), a master gene of lysosomal function and autophagy. In vivo administration of tamoxifen to the CLN7 Show less