In a breakthrough that may lead to better dementia treatment for people, blood from mice with a high level of fitness has been shown to improve brain function in couch-potato companions.
The brains of older adults with a high level of activity, such as young mice, were found to benefit from blood injections.
A single inflammation-fighting protein called clusterin seemed largely responsible for the benefit.
While experiments with mice cannot be guaranteed to transfer to people, researchers found an increase in the levels of protein in older adults who exercised.
Professor Tony Wyss-Coray of Stanford School of Medicine, California said that the discovery may open up the possibility of treatments to reduce brain inflammation and slow down the progression of neurodegenerative diseases.

Study: The brain function of ultra-fit mice was boosted by blood taken from them. This discovery could lead to new therapies for people with dementia.
Exercise has been shown to have a variety of beneficial effects on the brain.
Wyss Coray said: “We have discovered that the exercise effect is largely due to blood factors, and that we can transfer this effect to an older, less active individual.”
Researchers found that injecting blood from the “marathoner” mice to reduce inflammation in brains of the restrained mice led to a reduction of inflammation.
According to Wyss–Coray, anyone who has ever had flu symptoms can understand the impact on cognitive function caused by a viral infection.
He said: ‘You get lethargic, you feel disconnected, your brain doesn’t work so well, you don’t remember as clearly.’
It’s likely that the inflammation caused by the infection has led to this condition. When the body’s immune system is able to fight off infection, inflammation can spread into their brain.
Wyss–Coray also stated that a comparable type of neuroinflammation is strongly associated with neurodegenerative disorders such as Alzheimer’s.
These experiments were based on the fact mice love running. You can give a mouse cage access to a wheel that is a couple inches wide and it will run 4-6 miles per night.
You can lock the wheel so that the mouse logs only a tiny fraction of your exercise.
Researchers placed functional and locked running wheels in the cages for 3-month-old laboratory mice. These lab mice are similar to humans 25 years old metabolically.
Marathoner mice had significantly more neurons than sedentary mice after a month of running.
Next, researchers took blood samples from runners mice and sedentary rodents as controls.
After three days, they injected plasma from the marathoner and couch-potato mice to other sedentary mouse.
In two lab memory tests, marathoner plasma-injected sedentary mice outperformed those who had been given couch-potato plasma.
Furthermore, plasma taken from marathoner mice by sedentary mice resulted in more new neuron-generating cells.
Tests were conducted to determine how the mice learned that certain sounds indicated that the cage floor was about to shock them with an electric shock.
This was calculated by researchers looking at how the mice react to shocks.
Wyss Coray claimed that mice that were given runner blood were much smarter than the ones Wyss-Coray observed. The blood of runners clearly did something to the brain even though it was not delivered directly.
Clusterin, a protein found in the plasma of marathoner mice, was also removed by researchers to negate its anti-inflammatory effects on the brains and sedentary mice.
Scientists found no other proteins that had similar results.
The blood of marathoners had significantly higher levels of clusterin than that found in couch potato runners.
Additional experiments revealed that clusterin can bind to brain endothelial cell receptors, which are the cells that line blood vessels in the brain.

While experiments with mice cannot be translated to human beings, researchers found an increase in the levels of protein after examining the bloodstream of people over 60 who exercised (stock photo).
WyssCoray said that the majority of Alzheimer’s patients have inflamed cells. Wyss-Coray’s research revealed that blood cells can transmit chemical signals to the brain from the blood.
Even though clusterin is administered externally, the drug was able reduce brain inflammation in mice from two strains.
Researchers also discovered that twenty military veterans who had mild cognitive impairment and were a precursor for Alzheimer’s disease experienced elevated levels of clusterin in their blood after they completed a six month aerobic exercise program.
Wyss-Coray speculated that a drug that enhances or mimics clusterin’s binding to its receptors on brain endothelial cells might help slow the course of neuroinflammation-associated neurodegenerative diseases such as Alzheimer’s.
This research was published in Nature.