Upper limb motor impairment is a common sequela of stroke and significantly compromisses patients’ activities of daily living and quality of life . Non-invasive vagus nerve stimulation （nVNS） ，developed from conventional vagus nerve stimulation （VNS）， is a safer， more convenient， and cost-effective neuromodulation technique with the adventage of avtive regulation， It has been increasingly applied in clinical practice and neuroscience research，and its therapeutic potential in post-stroke upper limb rehabilitation has been preliminaruly demonstrated. This systematic review comprehensively examines the mechanistic basis and clinical advancements of nVNS in treating upper limb motor dysfunction following stroke， with a particular focus on the International Classification of Functioning， Disability and Health （ICF） framework. From the perspectives of body function， individual activity， and social participation， the rehabilitative effects of nVNS are analyzed in an integrated manner. Specifically， nVNS enhances neural plasticity， mitigates inflammatory responses， and improves cerebral perfusion in ischemic regions by modulating the secretion of neurotransmitters such as norepinephrine， acetylcholine， and γ-aminobutyric acid， thereby promoting neurological recovery at the body function level. Moreover， the synergistic application of nVNS with rehabilitative training has been shown to sustainably improve motor function and activities of daily living， yielding functional benefits that extend to the levels of individual activity and social participation.Building upon this foundation， the present study examines the technical challenges confronting nVNS and proposes future research trajectories focusing on parameter optimization， multimodal neuromodulation integration， and rehabilitation for lower limb dysfunction. These directions aim to facilitate precision personalized therapeutics for stroke patients.

To conduct the association between vitamin B12 and mental health in children and adolescents. Five databases were searched for observational studies in any language reporting on mental health and vitamin B12 levels or intake in children and adolescents from inception to March 18, 2022. Two authors independently extracted data and assessed study quality. Qualitative and quantitative analysis of data were performed. The review was registered in the PROSPERO database (CRD42022345476). Fifty six studies containing 37,932 participants were identified in the review. Vitamin B12 levels were lower in participants with autism spectrum disorders (ASD) (standardized mean difference [SMD], −1.61;95% confidence interval [95% CI], −2.44 to −0.79; p ＜ 0.001), attention deficit hyperactivity disorders (SMD, −0.39; 95% CI, −0.78 to −0.00; p = 0.049) compared with control group. Vitamin B12 intake were lower in participants with ASDs (SMD, −0.86; 95% CI, −1.48 to −0.24; p = 0.006) compared with control group, but showed no difference between depression group (SMD, −0.06; 95% CI, −0.15 to 0.03; p = 0.17) and the control group. Higher vitamin B12 intake were associated with lower risk of depression (odds ratio [OR], 0.79; 95% CI, 0.63−0.98; p = 0.034) and behavioral problems (OR, 0.83; 95% CI, 0.69−0.99; p = 0.04). The vast majority of included studies supported potential positive influence of vitamin B12 on mental health, and vitamin B12 deficiency may be a reversible cause for some mental health disorders in children and adolescents.