Janelle Perez and colleagues at NYU Rory Meyers — building on a Penn-led collaboration — analyzed 440 women in the Women's Interagency HIV Study (261 with HIV, 179 without) and found that monocyte epigenetic age, but not a multi-tissue epigenetic clock, predicted non-somatic depression symptoms — anhedonia, hopelessness, feelings of failure — across both groups. [1] The finding, published May 4 in The Journals of Gerontology Series A, cross-references the March 6 Scientific Reports paper showing altered HDAC5 and SIRT2 distribution in monocytes from people with major depression. [2] Yesterday's paper carried the cell-type and phenotype specificity as the structural news — the assay is narrower than the press release makes it sound, and that's the point. Today the validation cohort is the question: the WIHS sample skews older, immunocompromised, and ethnically specific, so the next study has to clear treatment-stratification confounding before the assay reads as a screening test. The ordinary-language version is that immune cells age fastest in people who already feel hopeless, and a blood test for that may be coming — it is not here yet.

-- KENJI NAKAMURA, Tokyo