From: judgebean23x@gmail.com   
      
   Science and technology    
   Alzheimer's disease    
      
   Fungus, the bogeyman    
   A curious result hints at the possibility dementia is caused by fungal   
   infection    
   Oct 24th 2015    
      
   Scarred by fungi?    
      
   LIKE cancers and heart disease, Alzheimer's is a sickness of the wealthy. That   
   is because it is a sickness of the old. A study carried out in Spain in 2008   
   suggested that the risk of developing it doubles for every five years you live   
   beyond 65. A richer    
   world means a longer-lived world--and that, in turn, means a world which will   
   suffer more and more from dementia. At least 40m people are thought to be   
   affected by it already. The true number is likely to be higher, as many   
   sufferers, particularly in the    
   early stages of the disease, have yet to be diagnosed.    
   What actually causes Alzheimer's disease, though, is obscure. Workers in the   
   field know that tangles and plaques of misshapen proteins play a big role.   
   These accumulate in and between nerve cells, eventually killing them to create   
   voids in the brain (see    
   picture). It may be that the accumulation of these proteins is merely a   
   biochemical ill to which human flesh is unfortunately heir, and which is a   
   normal (if unwelcome) consequence of ageing. But some researchers doubt that,   
   and are searching for    
   external causes. There is evidence, in varying degrees, for everything from   
   bacterial or viral infections, via head injuries to smoking. But a paper just   
   published in Scientific Reports adds another possibility to the pot. A group   
   of researchers led by    
   Luis Carrasco of the Autonomous University of Madrid, in Spain, have raised   
   the idea that the ultimate cause of Alzheimer's is fungal.    
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   Dr Carrasco and his team examined brain tissue from 25 cadavers, 14 of which   
   belonged to people who had had Alzheimer's disease when alive. The other 11   
   (who had an average age of 61, versus 82 for the Alzheimer's sufferers) had   
   been Alzheimer's-free.    
   That may sound like a small sample from which to draw conclusions, but the   
   signal the researchers found was overwhelming. Every single one of the   
   Alzheimer's patients had signs of fungal cells of various sorts growing in his   
   or her neurons. None of the    
   Alzheimer's-free brains was infected.    
   Assuming Dr Carrasco and his team have made no methodological errors (and   
   there is no suggestion that they have), then the question is one of causation.   
   Do fungi usher in the disease, or does the disease usher in the fungi? An   
   observational study like    
   this cannot answer that question. But Dr Carrasco and his colleagues point out   
   that what is known about Alzheimer's fits with what is known about fungal   
   infections. Alzheimer's progresses slowly, as do untreated fungal infections.   
   Alzheimer's patients    
   exhibit signs of inflammation and an aroused immune system, which fungal   
   infection might be expected to trigger. And the damaged blood vessels observed   
   in many people with Alzheimer's fit with Dr Carrasco's observation of fungus   
   growing in these vessels.    
   If fungal infection did turn out to be responsible for Alzheimer's, that would   
   be excellent news. Medicine already possesses plenty of anti-fungal   
   medications that could be raided to produce anti-Alzheimer's drugs. But Dr   
   Carrasco's evidence, while    
   intriguing, is far from conclusive. 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.   
   After all, says Ian Le Guillou of the Alzheimer's Society, a British charity,   
   the disease is thought to    
   damage the blood-brain barrier, an immunological shield which keeps the brain   
   safe from pathogens and toxins. The presence of fungi might merely reflect a   
   greater susceptibility to infection.    
   Dr Carrasco and his team think a clinical trial of anti-fungal drugs is the   
   next logical step. But there is yet another possibility. In the absence of a   
   definitive ultimate cause, it may be that the symptoms of Alzheimer's disease   
   can arise from many    
   different types of insult to the brain. There have been several papers, says   
   Dr Le Guillou, that have found correlations between various infectious   
   organisms and Alzheimer's. "It could be a bit like the Mississippi river,"   
   says Dr Hardy. "You can start    
   in all sorts of places, but eventually you're going to end up in New Orleans."   
   If Alzheimer's is a general response to all sorts of neurological triggers   
   then it may be that the fungal infections found by Dr Carrasco are simply one   
   of a long list of    
   causes.    
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