Recent studies have shown that cerebrospinal fluid (CSF) levels of soluble triggering receptor expressed on myeloid cells 1 (sTREM1) are elevated in individuals with Alzheimer’s disease (AD), though the relationship between CSF sTREM1 and hippocampal atrophy remains to be elucidated. This evidence concerns the gene TREM1 and early-onset autosomal dominant Alzheimer disease.