CSF biomarkers correlate with cerebral blood flow on SPECT in healthy elderly.

BACKGROUND The preclinical patterns of biological markers for Alzheimer's disease (AD) in vivo need further exploration. The aim of this study was therefore to investigate CSF biomarkers, regional cerebral blood flow (rCBF) and cognitive performance in cognitively healthy older individuals. METHOD Within a 2-week period, 32 cognitively healthy older individuals underwent CSF analysis, rCBF measurement and cognitive testing. The CSF was analysed for β-amyloid(1-42) (Aβ42), total tau protein (T-tau) and hyperphosphorylated tau protein (P-tau). The rCBF results were analysed with statistical parametric mapping to investigate rCBF covariance with the other measurements. RESULTS High CSF P-tau and T-tau levels correlated with decreased rCBF in the right superior posterior medial frontal lobe whereas high CSF P-tau levels also correlated with increased rCBF in the left fronto-temporal border zone area. No significant covariance was seen between rCBF and CSF Aβ42. Neither CSF P-tau and T-tau levels nor rCBF in the current right frontal and left posterior locations were associated with cognitive performance. CONCLUSIONS Our findings suggest a possible correlation between tau pathology and blood flow abnormalities in individuals without any overt cognitive symptoms. An association with AD development is possible but other explanatory mechanisms cannot be excluded.