A substance found in foods like pomegranates, strawberries, and walnuts restored the ability to detect and remove damaged cells in mice modeling Alzheimer's disease, scientists report in a new paper.
The same research team previously found a form of vitamin B3 called nicotinamide riboside (NR) helps remove damaged mitochondria from the brain.
When these neurological 'clean up' systems are interrupted, the junk starts to pile up, laying the groundwork for neurodegenerative diseases like Alzheimer's and Parkinson's.
"Many patients with neurodegenerative diseases experience mitochondrial dysfunction, also known as mitophagy. This means that the brain has difficulties removing weak mitochondria, which thus accumulate and affect brain function," says University of Copenhagen biochemist Vilhelm Bohr.
"If you are able to stimulate the mitophagy process, removing weak mitochondria, you will see some very positive results."
Getting these cerebral garbage trucks up and running again means some of that brain trash associated with Alzheimer's – which eventually contribute to the amyloid plaques and neurofibrillary tangles that characterize the disease – can be cleared away, so the whole system runs a bit more smoothly for a bit longer.
In their previous study, mice with a model of Alzheimer's disease (AD) received the compound NR as a supplement, reducing the tangled proteins and DNA damage in their brains by boosting production of an essential metabolic coenzyme called nicotinamide adenine dinucleotide (NAD).
Now, Bohr and colleagues have found urolithin A, the substance found in pomegranates, offers the struggling brain a similar boost.
The researchers found the AD model mice that were given long-term treatment with urolithin A had improved abilities in learning, memory, and sense of smell.
It affected a protein called cathepsin Z, which appears to be overactive in AD brains, and play a role in inflammation. Urolithin A treatment limited production of the protein, to a level on par with non-Alzheimer's brains. In its absence, certain cellular processes that help to break down biological waste were restored.
Urolithin A treatment was also found to modulate immune responses and other physiological pathways specific to AD.
Supplements like this won't necessarily prevent or cure diseases like Alzheimer's, but research like this suggests they might help the body keep tidying up the growing piles of molecular debris, potentially slowing disease progression.
"The advantage of working with a natural substance is the reduced risk of side effects," Bohr says.
"Several studies so far show that there are no serious side effects of NAD supplementation. Our knowledge of urolithin A is more limited, but as I mentioned, clinical trials with urolithin A have been effective in muscular disease, and now we need to look at Alzheimer's disease."
Since the results are based on mice, we can't be certain that urolithin A will have the same effects on human brains until clinical studies proceed. Nor can it be concluded that piling pomegranate seeds and strawberries on your cereal will have a significant impact on cognitive health. But the researchers are feeling confident enough to continue digging.
"Even though the study was conducted on mouse models, the prospects are positive," says Bohr.
"We still cannot say anything conclusive about the dosage. But I imagine that it is more than a pomegranate a day. However, the substance is already available in pill form, and we are currently trying to find the right dosage."
This research was published in Alzheimer's & Dementia.