The ambivalence of clinical results may be closely related to several factors: (1) differences in patient staging, as positive trials predominantly included patients with early-stage PD, while negative trials encompassed a broader range of disease stages, where neuronal damage may have become irreversible in late-stage patients (Yoritaka et al., 2018)
Symptoms of B12 deficiency include exhaustion no matter how much you sleep, muscle weakness and frequent cramping, constipation, loss of appetite and unexplained weight loss, numbness or tingling in the hands and feet, depression, and problems with memory and focus
Clinical trials show average weight loss of 24 kg over 48 weeks at the lowest dose, though individual results vary widely based on metabolic factors, adherence, and lifestyle
So do oral medications
Cyclin E associates with CDK2, and pushes the cell from G1 to S phase (Ohtsubo et al., 1995)