Association between thiamine decrease and neuropsychiatric symptoms in gastrointestinal and hematological cancer patients receiving chemotherapy.

BACKGROUND Clinical evidence of thiamine-related neuropsychiatric symptoms, including the initial stage, is limited because serum thiamine levels tend to be evaluated only for patients who develop severe neuropsychiatric symptoms suspected to be related to severe thiamine deficiency. This study aimed to evaluate the relationship between thiamine decline and neuropsychiatric symptoms, including initial symptoms, and the effect of chemotherapy on serum thiamine levels in gastrointestinal and hematological cancer patients receiving chemotherapy. METHOD We retrospectively identified 87 patients who were diagnosed with gastrointestinal and hematological cancers at our hospital. We evaluated the risk factors associated with neuropsychiatric symptoms, including initial symptoms (neuropsychiatric symptoms), the relationship between the presence of neuropsychiatric symptoms and serum thiamine levels, and changes in serum thiamine levels after chemotherapy. RESULTS Logistic regression analysis identified thiamine decline as a significant factor associated with neuropsychiatric symptoms (p < 0.001, odds ratio = 0.040, 95% confidence interval [CI]: 0.010-0.163). The Mann-Whitney U test showed that patients with neuropsychiatric symptoms had significantly lower serum thiamine levels (19.5 ± 5.4 ng/mL, n = 39) than patients without neuropsychiatric symptoms (31.9 ± 14.2 ng/mL, n = 48) (p = 0.001). In hematological cancer patients, serum thiamine levels gradually declined after chemotherapy, with the lowest levels at 5-8 weeks (23.5 ± 7.6 ng/mL, P = 0.035 vs. 0 weeks, Wilcoxon rank sum test). CONCLUSION Our study showed that a decrease in serum thiamine levels can be a risk factor for neuropsychiatric symptoms, and chemotherapy can lead to a decrease in serum thiamine levels.