Part 1 focused on the study’s clinical biomarkers. Part 2 highlighted its epigenetic clocks. Now we’ll look at rejuvenation of cognitive function.
Charts for this study’s most relevant human aging applications – measured by the new human-rat relative biological age clock – were in supplementary data due to combining study untreated tissue samples into clock training data. Reanalyses showed:
“Using the final version of the epigenetic clocks, we find that treatment effects become even more significant especially for the hypothalamus.”
Human-rat relative clock percentages of rejuvenation were:
- “Blood 70.6%
- Liver 79.4%
- Heart 61.6%
- Hypothalamus 20.9%”
The Discussion section addressed hypothalamus rejuvenation:
“Why does plasma fraction treatment not reduce brain epigenetic age by the same magnitude as it does other organs? We can only begin to address this question after having first understood what epigenetic aging entails.
As it stands, our knowledge in this area remains limited, but it is nevertheless clear that:
- Epigenetic aging is distinct from the process of cellular senescence and telomere attrition,
- Several types of tissue stem cells are epigenetically younger than non-stem cells of the same tissue,
- A considerable number of age-related methylation sites, including some clock CpGs, are proximal to genes whose proteins are involved in the process of development,
- Epigenetic clocks are associated with developmental timing, and
- Relate to an epigenomic maintenance system.
Collectively, these features indicate that epigenetic aging is intimately associated with the process of development and homeostatic maintenance of the body post-maturity.
- While most organs of the body turnover during the lifetime of the host, albeit at different rates, the brain appears at best to do this at a very much slower rate.
- While most tissues harbor stem cells that are necessary for replenishment and turnover, stem cells in adult brain have only been detected in a defined and very limited area of the subventricular zone, olfactory bulb (in rats), hippocampus and hypothalamic proliferative region.
As such, if plasma fraction treatment’s rejuvenating effect is:
- Mediated through the process of development and
- Involves tissue stem cells
then its effect on epigenetic age of the brain would appear to be modest, which indeed it does.
It is to be noted however, that improving brain function does not depend on neurogenesis as much as it does on synapse formation and factors such as NMDA receptors, which decline in density with age.
Assessment of plasma fraction treatment on cognitive function (learning and memory). Rats were subjected to Barnes maze test – nine consecutive days of test where the time (in seconds) required by rats to find the escape hole (latency) was recorded and plotted. Error bars depict 2 standard errors.
Within a month of plasma fraction treatment, rats exhibited significantly reduced latency to escape, i.e., they learned and remembered better. After the second month, treated rats began with a slightly reduced latency period compared to untreated old rats, and once again, they learned much faster than the latter.
By the third month, it was clear that treated rats remembered the maze much better than untreated ones even from the first day of test as their latency period was significantly reduced. By the end of the test period, their latency was similar to that of young rats. This feature was sustained and repeated in the fourth month.”
Not sure why there’s a 62-day gap between “Second month” and “Third month.” Maybe it had something to do with “First month” starting 10 days after the first treatment and “Third month” similarly starting 13 days after the second treatment?
Many of us know older people who lived well past their time of good cognitive function:
- We see how they’re helpless and dependent; and
- We see how others take advantage of them in their morbidity phase, where healthspan stops increasing but lifespan continues.
We can make personal plans for that day, sure. But let’s also put some urgency into applying this study’s new human-rat relative biological age clock, and make:
“A step change in aging research. Although conservation of aging mechanism could be equally deduced from the existence of multiple individual clocks for other mammals (mouse, dog), the single formula of the human-rat clock that is equally applicable to both species effectively demonstrates this fact.”