Every year, more people over the age of 65 are suffering from dementia. Researchers are still searching for a cause, but a new study offers a fascinating possibility: some cases of Alzheimer's may be linked to a simple brain fungus.
The study appeared this week in Nature Scientific Reports, and is already making headlines and stirring up controversy in the research community. Molecular biologists Diana Pisa, Luis Carrasco, and colleagues studied 25 cadavers, 14 of which belonged to people with Alzheimer's. What they discovered seemed almost impossible. All 14 of the Alzeheimer's sufferers had a fungal infection.
Is it possible that this fungus caused the symptoms of dementia? Pisa and her colleagues couldn't rule it out. There are many treatments for fungal infections already available, and the researchers say the next step will be to test their effectiveness against Alzheimer's in living organisms.
The problem is that fungus can't explain all cases of dementia, as The Economist points out:
John Hardy, a neuroscientist at University College, London, points out that one (albeit rare) cause of Alzheimer's is well-understood. In a few unlucky families the disease appears to be an inherited disorder, caused by mutations of one of three genes. If a fungal infection were the ultimate cause, then those genetic mutations would have to make their carriers so susceptible that 100% of them end up infected, something he believes is unlikely. And the very clarity of Dr Carrasco's result also makes Dr Hardy suspicious.
If that result is right, though, it is still possible that the correlation runs the other way, with Alzheimer's opening the brain to fungal infection.
It's also very likely that Alzheimer's, like cancer, is not a single ailment with one cause. There may be dozens of reasons why people develop dementia — all of which respond to different kinds of therapy. Still, if this study leads us to just one therapy for one kind of dementia, that will be a win.
Read the full scientific paper at Nature Scientific Reports.
Image of brain fungus via Neurology.