Association of plasma BDNF levels with different stages of Alzheimer's disease: a cross-sectional study

Unlocking Alzheimer's Disease: The Role of BDNF Signaling in Neuropathology and Treatment

Alzheimer's disease (AD) remains one of the most debilitating neurodegenerative disorders, with its pathological hallmark being progressive cognitive decline and memory loss. Recent research has illuminated the crucial role of the brain-derived neurotrophic factor (BDNF) in the central nervous system (CNS), highlighting its impact on neurogenesis, synaptic plasticity, and neuronal survival. Dysregulation of the BDNF signaling axis, particularly the imbalance between its precursor form and mature BDNF, is strongly implicated in the pathophysiology of AD. This review explores the molecular mechanisms through which BDNF modulates AD neuropathology and presents novel therapeutic strategies to activate BDNF signaling. We focus on the potential of BDNF activators, such as TrkB agonists and mimetic molecules, to restore synaptic function and ameliorate cognitive deficits in AD. Furthermore, we examine the challenges in translating these findings into clinical practice, including issues with blood-brain barrier penetration and the need for precise receptor targeting. The review emphasizes the therapeutic potential of repurposed drugs, including statins and metformin, in enhancing BDNF signaling and offers new insights into the future of AD treatment. Ultimately, this work provides a compelling argument for BDNF-based therapies as a promising avenue for mitigating the cognitive decline associated with Alzheimer's disease, signaling a hopeful direction for future research and clinical trials.

Association between Plasma Brain-derived Neurotrophic Factor Level and Alzheimer's Disease: A Mendelian Randomization Study

BACKGROUND

High brain-derived neurotrophic factor (BDNF) concentrations have been found to be associated with a decreased risk of Alzheimer's disease (AD) in observational studies, but the causality for this association remains unclear. Therefore, we aimed to examine the association between genetically determined plasma BDNF levels and AD using a two-sample Mendelian randomization (MR) method.

METHODS

Twenty single-nucleotide polymorphisms associated with plasma BDNF concentrations were identified as genetic instruments based on a genome-wide association study with 3301 European individuals. Summary-level data on AD were obtained from the International Genomics of Alzheimer's Project, involving 21,982 AD cases and 41,944 controls of European ancestry. To evaluate the relationship between plasma BDNF concentrations and AD, we employed the inverse-variance weighted method along with a series of sensitivity analyses.

RESULTS

The inverse-variance weighted MR analysis showed that genetically determined BDNF concentrations were associated with a decreased risk of AD (odds ratio per SD increase, 0.91; 95% confidence interval, 0.86-0.96; p =0.001). The association between plasma BDNF concentrations and AD was further confirmed through sensitivity analyses using different MR methods, and MR-Egger regression suggested no directional pleiotropy for this association.

CONCLUSION

Genetically determined BDNF levels were associated with a decreased risk of AD, suggesting that BDNF was implicated in the development of AD and might be a promising target for the prevention of AD.

Exercise Intervention for Alzheimer's Disease: Unraveling Neurobiological Mechanisms and Assessing Effects

Alzheimer's disease (AD) is a progressive neurodegenerative disease and a major cause of age-related dementia, characterized by cognitive dysfunction and memory impairment. The underlying causes include the accumulation of beta-amyloid protein (Aβ) in the brain, abnormal phosphorylation, and aggregation of tau protein within nerve cells, as well as neuronal damage and death. Currently, there is no cure for AD with drug therapy. Non-pharmacological interventions such as exercise have been widely used to treat AD, but the specific molecular and biological mechanisms are not well understood. In this narrative review, we integrate the biology of AD and summarize the knowledge of the molecular, neural, and physiological mechanisms underlying exercise-induced improvements in AD progression. We discuss various exercise interventions used in AD and show that exercise directly or indirectly affects the brain by regulating crosstalk mechanisms between peripheral organs and the brain, including "bone-brain crosstalk", "muscle-brain crosstalk", and "gut-brain crosstalk". We also summarize the potential role of artificial intelligence and neuroimaging technologies in exercise interventions for AD. We emphasize that moderate-intensity, regular, long-term exercise may improve the progression of Alzheimer's disease through various molecular and biological pathways, with multimodal exercise providing greater benefits. Through in-depth exploration of the molecular and biological mechanisms and effects of exercise interventions in improving AD progression, this review aims to contribute to the existing knowledge base and provide insights into new therapeutic strategies for managing AD.