Fig. 2

Scatter plots of the CSF solute levels by age. The pCO₂ in the CSF showed a significant negative correlation with age (R = − 0.65, p = 0.0065), while no other measured variables showed any significant correlations with age. CSF, cerebrospinal fluid; HCO₃⁻, bicarbonate; pCO₂, carbon dioxide partial pressure; pO₂, oxygen partial pressure