Predicting Reduction of Cerebrospinal Fluid beta-Amyloid 42 in Cognitively Healthy Controls

• IMPORTANCE Alzheimer disease has a long preclinical stage characterized by beta-amyloid (A beta) accumulation without symptoms. Several trials focus on this stage and use biomarkers to include A beta-positive participants, but an even earlier prevention of A beta accumulation may be an effective treatment strategy. OBJECTIVE To determine whether people who appear to be A beta negative but are at high risk for A beta positivity within the near future can be identified. DESIGN, SETTING, AND PARTICIPANTS Longitudinal biomarker cohort study involving 35 cognitively healthy individuals who underwent cerebrospinal fluid (CSF) sampling for up to 3 years during the study (October 24, 2005, to September 1, 2014). All participants had normal CSF A beta 42 levels at baseline. MAIN OUTCOMES AND MEASURES Predictors of future A beta positivity (levels of CSF A beta 42 declining below a previously validated cutoff level of 192 ng/L) tested by random forest models. Tested predictors included levels of protein in the CSF, hippocampal volume, genetics, demographics, and cognitive scores. RESULTS The CSF A beta 42 levels declined in 11 participants, and the CSF became A beta positive. The baseline CSF A beta 42 level was a strong predictor of future positivity (accuracy, 79% [95% CI, 70%-87%]). Ten of 11 decliners had baseline CSF A beta 42 levels in the lower tertile of the reference range (<225 ng/L), and 22 of 24 nondecliners had baseline CSF A beta 42 levels in the upper 2 tertiles (similar to 225 ng/L). A high CSF P-tau level was associated with decline (accuracy, 68%; 95% CI, 55%-81%). CONCLUSIONS AND RELEVANCE Baseline CSF A beta 42 levels in the lower part of the reference range are strongly associated with future A beta positivity. This finding can be used in trials on very early prevention of Alzheimer disease to identify people at high risk for Ab accumulation as defined by low CSF A beta 42 levels.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Neurologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Neurology (hsv//eng)

Nyckelord

MODERATE ALZHEIMERS-DISEASE

BIOMARKER SIGNATURE

NORMAL INDIVIDUALS

CLINICAL-TRIALS

PATHOLOGY

DECLINE

TAU

PET

NEURODEGENERATION

DEPOSITION

Clinical Neurology

LSTEIN MF

1975

JOURNAL OF PSYCHIATRIC RESEARCH

V12

P189

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