CSF biomarker levels in early and late onset Alzheimer's disease

ObjectiveTo compare CSF levels of beta-amyloid 1–42 (Aβ1–42), total tau (tau) and tau phosphorylated at threonine 181 (ptau-181) between AD patients and controls according to age.Methods248 AD patients (48% men) and 127 controls (51% men, 22 volunteers and 105 subjective complainers) underwent lumbar puncture. Both patients and controls were divided into a young (<65 years) and old (≥65 years) group.ResultsAll three biomarkers showed main effects of diagnosis (p < 0.001). There was an interaction between diagnosis and age for all three biomarkers (p < 0.05), as old controls had lower Aβ1–42 and higher (p)tau than young controls (Aβ1–42 699 ± 250 versus 866 ± 191 pg/ml, tau 408 ± 245 versus 243 ± 102 pg/ml, ptau-181 60 ± 28 versus 42 ± 15 pg/ml), but there was no difference according to age among AD patients (Aβ1–42 451 ± 178 versus 425 ± 146 pg/ml, tau 741 ± 460 versus 798 ± 467 pg/ml, ptau-181 91 ± 42 versus 91 ± 41 pg/ml).ConclusionWe found that the older control group had lower Aβ1–42 and higher (p)tau compared to the younger control group. This suggests that older individuals may have AD pathology, even in the absence of objective cognitive impairment.