Premium
P2–131: Feasibility and usefulness of longitudinal beta–amyloid 1–42 levels in CSF of patients with various cognitive and neurological disorders
Author(s) -
Bouwman Femke,
Flier Wiesje,
Schoonenboom Saskia,
Van Elk Eef,
Kok Astrid,
Scheltens Philip,
Blankenstein Marinus
Publication year - 2006
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2006.05.969
Subject(s) - medicine , dementia , analysis of variance , cerebrospinal fluid , longitudinal study , cognitive impairment , disease , cerebral spinal fluid , gastroenterology , pathology , anesthesia
Background: Measuring protein levels in CSF has gained wide acceptance for the differential and early diagnosis of dementia. Little is known, however, about longitudinal changes in CSF biomarkers that are of potential use to study the course of the disease and effects of treatment. Objective(s): To evaluate changes in CSF -amyloid1-42 levels with time and to assess the influence of storage of specimen and variability of assays on the results. Methods: 114 memory clinic patients (54% male, age 67 9 years, 44% Alzheimer’s disease, 33% mild cognitive impairment, 15% subjective memory complaints, 8% other neurological disease) were recruited between 2000 and 2004. All patients underwent two spinal taps (mean follow-up time 1.8 year). -amyloid1-42 was measured with a sandwich ELISA (Innotest -amyloid1-42; Innogenetics, Ghent, Belgium). The intraassay variability was 6.5%. The inter-assay variability was 6.9%-12.6%. First, baseline and follow-up -amyloid1-42-levels were determined in separate assays, each following spinal tap. Second, to circumvent interassay variability, baseline and follow-up samples were run in the same assay at the time of the second spinal tap. In addition, variance of repeated -amyloid1-42 assessment in baseline CSF-samples was calculated. Results: Mean -amyloid1-42-level at baseline was 477 232 pg/ml. Mean -amyloid1-42-level at follow up was 519 249 pg/ml (p 0.00). Repeated mean baseline -amyloid1-42-level was 481 49 pg/ml (p 0.7). Intraindividual variance of the baseline and follow up CSF-sample pairs run on separate assays was 26% (SD20). In contrast a variance of 14% (SD12) was found within CSF-sample pairs run on the same assay. The variance of repeated -amyloid1-42 assessment in baseline CSF-samples was 19% (SD 17). Storage time was found not to be associated with differences in -amyloid1-42-level. Conclusions: In case of repeated spinal taps, determination of -amyloid1-42-levels should be performed in the same assay. However, the variation of repeated -amyloid1-42 assessment in the same CSF sample is larger than the variance between baseline and follow-up CSF-samples in the same assay. This might imply, that with the methodological limitations of the present ELISA, repeated spinal taps are not feasible in a clinical setting. The biological significance of repeated spinal taps in individual patients remains to be established.