Betty Tijms and colleagues published in Annals of Neurology this month that normal amyloid marks in cerebrospinal fluid (CSF) do not exclude incident Alzheimer’s disease (AD).
Decreased levels of amyloid β 1-42 in cerebrospinal fluid (CSF) are a robust marker for Alzheimer’s disease (AD) and indicate the presence of amyloid plaques in the brain. Still, 15-30% of people who have mild cognitive impairment and normal amyloid develop an AD type of dementia. We analysed normal amyloid β 1-42 levels in non-demented memory clinic patients and observed that a range of normal values exist that is associated with an up to 21 fold increased risk show cognitive decline over time.
These results indicate that in non-demented people normal amyloid β 1-42 values should be taken into account when studying the earliest changes in the brain that are relevant for AD.
FIGURE: Survival curves for the time to clinical progression in nondemented subjects. pMCI = subjects with mild cognitive impairment who showed clinical progression; pSCD = subjects with subjective cognitive decline who showed clinical progression. Separate lines indicate progression according to quintiles of cerebrospinal fluid amyloid β 1-42 levels.