Demographic characteristics of patient cohorts.

Data are number of patients (%) or median (range), unless otherwise stated. n.a., not applicable; n.d., no data available. The VE patient CSF cohort and the Yakutian control CSF cohort did not statistically differ with respect to gender distribution (P value of 0.396; Pearson's Chi-Square test) or age (P value of 0.234; Student's t-test). #Data from medical history (not obtainable from all patients). +Detailed assessment of neuropsychological deficits was not possible because of the language barrier, but we were able to obtain data on cognitive function together with our translators in 14 of the 20 VE patients.