Young Blood for Old Brains: The Quest to Slow Brain Aging

Aging leads to the degradation of function in nearly all tissues and organs. This process is marked by significant shifts in gene expression and changes in concentrations of all types of biological molecules. Recent technological progress has allowed biologists to measure an unprecedented number of these molecules throughout an organism, providing unique insights into the physiological and pathological conditions of cells and organs, including the aging process. Large-scale proteomic studies in humans demonstrate dramatic shifts in the composition of the blood and cerebrospinal fluid proteomes with age allowing researchers to estimate brain age and identify proteins linked to cognitive decline, neurodegeneration, and dementia. While brain cell- and tissue-intrinsic factors are likely essential in driving the aging process, we find blood-borne factors from young humans and mice are sufficient to counteract aspects of brain aging and improve cognitive function in old mice, while blood plasma from old organisms is detrimental to young mice and impairs their cognition. These findings open opportunities to identify biomarkers and regulators of aging in general and for the brain and other organs specifically.