Can blood transfusions lead to neurologic rejuvenation?

Question

“We know [neurologic] rejuvenation exists. Now we have to figure out the bare minimum of therapeutics or genetic tinkering necessary for it to be safely translated into a human.”

In the article Blood Work: Scientists Uncover Surprising New Tools to Rejuvenate the Brain, the authors claim that:

the rejuvenating factors of young blood have shown not only that neurons can be generated throughout adulthood, but also that the maddening aspects of aging, such as memory loss and slower processing speed, can be partially reversed.

It is true that these things have been demonstrated?

(A good answer might also show the context in which these things have been demonstrated or the barriers in generalizing those results, if any.)

Answer 1

Apparently, yes. The same study seems to be discussed here in a radio format.
A predecesor group, from Stanford, saw the same thing (see TED talk here.)
At first glance, another separate demonstration of this seems to be described here.
The mechanism by which this works is not yet understood, but the effect seems to be real.

Answer 2

Quoting Megan Scudellari in the Nature Article 'Ageing research: Blood to blood', "For now, any claims that young blood or plasma will extend lifespan are false: the data are just not there. An experiment to test such claims would take upwards of six years — first waiting for the mice to age, then for them to die naturally, then analysing the data."

Amy Wagers emphasizes that no one has convincingly shown that young blood lengthens lives, and there is no promise that it will. Still, she says that young blood, or factors from it, may hold promise for helping elderly people to heal after surgery, or treating diseases of ageing.

Young mice blood has been studied to cause repair of age related damage such as cardiac hypertrophy, muscle dysfunction, demyelination processes and brain vasculature system in old mice. The mouse is the most common model organism for preclinical studies even though it has not proven particularly reliable at predicting the outcome of studies in humans.

Wyss-Coray one of the authors of the study mentioned in the question is a part of board of directors of a biotechnology start-up named Alkahest to explore the therapeutic implications of the mice findings in humans. The young mice blood treatment has been shown to have effects in old mice neural dysfunctions such as

1. Cardiac hypertrophy: Loffredo et.al. have concluded that treatment of old mice to restore GDF11 to youthful levels recapitulated the effects of parabiosis and reversed age-related hypertrophy, revealing a therapeutic opportunity for cardiac aging in 2013.

2. Muscle dysfunction: GDF11 systemically regulates muscle aging and may be therapeutically useful for reversing age-related skeletal muscle and stem cell dysfunction per conclusions of Sinha M et.al. in 2014.

3. Reversal of demyelination processes: Ruckh JM et.al. in 2012 concluded that enhanced remyelinating activity requires both youthful monocytes and other factors, and that remyelination-enhancing therapies targeting endogenous cells can be effective throughout life.

4. Improvement of brain vasculature system: Katsimpardi L et.al. in 2014 concluded that GDF11 alone can improve the cerebral vasculature and enhance neurogenesis. Studies in mice and Xenopus suggest that this protein is involved in mesodermal formation and neurogenesis during embryonic development. Research shows that there could be multiple forms of GDF11.

The identification of factors that slow the age-dependent deterioration of the neurogenic niche in mice may constitute the basis for new methods of treating age-related neurodegenerative and neurovascular diseases.