AGT and early-onset autosomal dominant Alzheimer disease: In the brain, AGT is mainly produced by astrocytes.18 CSF AGT has been shown to be elevated in Alzheimer’s disease, as a result of an upregulated RAS.18 Finally, we measured CSF levels of 27-hydroxycholesterol (27-OH), a cholesterol metabolite with negative effects on neurons and inflammation.19 Increased 27-OH has been previously linked to memory deficits, Alzheimer’s disease and other neurodegenerative conditions.20