Aging and Brain Rejuvenation as Systemic Events
It is always good to see more researchers talking openly about the prospects for treating aging, reversing dysfunction, and extending life. This review is open access, but the full paper is only available in PDF format at the moment:
Until recently, the aging process - the gradual detrimental effect of time on an organism that leads to death - was considered irreversible. However, research over the last 30 years has challenged this assumption, providing compelling evidence that the aging process can be affected by several factors, including the genetic composition of the organism, as well as the experiences the organism has with its environment. These findings indicate that aging is not a deterministic process, but is instead plastic, potentially availing itself to manipulation by means available to the fields of biology and medicine. The malleability of the aging process raises the exciting possibility that harnessing this plasticity may provide a means to slow or even reverse the aging process itself and rejuvenate physiological systems.[This is] particularly evident in the loss of plasticity and cognitive abilities occurring in the aged central nervous system (CNS). However, it is becoming increasingly apparent that extrinsic systemic manipulations such as exercise, caloric restriction, and changing blood composition by heterochronic parabiosis or young plasma administration can partially counteract this age-related loss of plasticity in the aged brain. In this review we discuss the process of aging and rejuvenation as systemic events. We summarize genetic studies that demonstrate a surprising level of malleability in organismal lifespan, and highlight the potential for systemic manipulations to functionally reverse the effects of aging in the CNS.
Based on mounting evidence, we propose that rejuvenating effects of systemic manipulations are mediated in part by blood-borne 'pro-youthful' factors. Thus systemic manipulations promoting a younger blood composition provide effective strategies to rejuvenate the aged brain. As a consequence, we can now consider reactivating latent plasticity dormant in the aged CNS as a means to rejuvenate regenerative, synaptic and cognitive functions late in life, with potential implications even for extending lifespan.