Alzheimer’s Disease Dementia as the Diagnosis Best Supported by the Cerebrospinal Fluid Biomarkers: Difference in Cut-Off Levels from Thai Experience

Objectives . To determine how beta-amyloid 1-42 (A β 1-42), total tau (tTau), and phosphorylated tau (pTau) levels in CSF behave in a cohort of Thai patients from the Memory Clinic in Bangkok, Thailand. Methods . During 2009–2011, twenty eight subjects from the memory clinic at Siriraj Hospital had CSF analysis for AD biomarkers. A β 1-42, tTau, and pTau (at amino acid 181) were measured in CSF by ELISA technique. Results . Mean of Thai mental state examination (TMSE) of 28 Thai cohort was 16.48 (6.63). Fourteen had AD, ten had non-AD dementia, and four non-cases were those with subjective memory complaint (SMC) without dementia. Mean CSF A β 1-42, tTau, ptau (181), and pTau/A β 1-42 in the AD group were 241.36 (60.14) pg/mL, 222.79 (212.24) pg/mL, 40.79 (27.84) pg/mL, and 0.18 (0.12) accordingly. Mean CSF A β 1-42, tTau, pTau (181), and pTau/A β 1-42 in the non-AD dementia group were 430.40 (125.18) pg/mL, 349.30 (692.16) pg/mL, 36.80 (14.90) pg/mL, and 0.09 (0.04) accordingly. Mean CSF A β 1-42, tTau, pTau (181), and pTau/A β 1-42 in the non-cases with SMC without dementia were 499.75 (93.44) pg/mL, 137.25 (62.74) pg/mL, 31.75 (17.48) pg/mL, and 0.06 (0.02). There is significant difference ( P < 0.05) among the 3 groups in CSF A β 1-42 and pTau/A β 1-42. We propose mean + 1.5 SD of CSF A β 1-42 in AD group (331.57 pg/mL) to be the cut-off point in Thai subjects. Conclusion . There are significant different in CSF A β 1-42 and CSF p-tau/A β 1-42 among those with AD, non-AD dementia and non cases with SMC without dementia in Thai cohort. Cut-off point of CSF A β 1-42 of 331.57 pg/mL is suggested in Thai study.