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Stanley Prusiner discovers Alzheimer's Disease is caused by prions - An Overview.

alzheimer's disease May 06, 2013
Stanley Prusiner Discovery

At the recent meeting of the American Psychiatric Association which I attended in San Francisco, I heard some very high-quality lectures especially by some of the invited keynote speakers among whom were several Nobel laureates and former president Bill Clinton (albeit by webcast since he was “under the weather”).

ME/CFS Cognitive Dysfunction and Dementia

One of the most prescient presentations for me though not strictly on the topic of ME/CFS and related disorders was the talk on neurodegenerative diseases by Nobel Laureate Stanley Prusiner. It is of interest for two reasons. His ideas are so revolutionary that they are still slow to make their way into conventional medicine despite being recognized by the Nobel committee in 1997. Second dementia is an illness that many of my patients fear they have and which many of us will develop. Knowing more about it may help us take steps to prevent or slow the course. Knowledge is power.

Stanley Prusiner Discovers Alzheimer's Dementia is Caused by Prions.

Prusiner started researching dementia in 1972 after working with a patient dying of Creutzfeldt-Jakob disease (CJD) a “rare” infectious form of dementia first identified among cannibalistic tribes in New Guinea. In 1982 he published a paper showing that this dementia could be transmitted in hamsters by protein molecules containing no DNA or RNA. Dr. Pruisner called these molecules “prions”. Dr. Pruisner was ridiculed for this idea since “everyone knew” that DNA or RNA must be present for any molecule to replicate itself. He faced an uphill battle but his research was so convincing that in 1997 he was awarded the Nobel Prize for medicine. Since then, he has gone on to found a whole field of exciting research.

Prusiner and others have shown that prions that are now accepted transmit CJD as well as mad cow disease and chronic wasting disease which affects deer and elk may be a cause of many if not most of the common neurodegenerative diseases in humans.

Many Neurodegenerative Diseases are Caused by Prions

Here’s how the story unfolds... It turns out that Alzheimer’s Disease, Parkinson’s Disease, Amyotrophic Lateral Sclerosis, Huntington’s Disease and even Chronic Traumatic Encephalopathy may be prion diseases. The prions actually start out as normal proteins in the brain of all of us. We all have the genes for the proteins that later become prions. That they are present in all mammals suggests that the proteins play some essential role in the body. As we age, some of these proteins are transformed into self-propagating molecules called prions. Once formed, prions fold and propagate. Amyloid protein forms plaques and tau protein form tangles. Plaques and tangles are the two prominent features found in the brain of Alzheimer’s patients on autopsy. Other conditions such as Parkinson’s and others have tangles but no plaques. The specific symptoms of each illness depend on where in the brain the tangles or plaques form. For example in Alzheimer’s they form first in the memory centres, in Parkinson’s in the basal ganglia which control movement.

Prusiner has shown that prions taken from the brains of healthy aged mice and injected into the brains of healthy mice cause the healthy mice to develop dementia. Furthermore, it is possible to breed mice that are genetically susceptible to prion diseases and become ill sooner and at lower doses of inoculation. So it seems that genetics is one risk factor but in humans this only accounts for 10 – 20% of cases of dementia. Infection by eating the brains of affected individuals (even before they become ill) as was the case in Papua New Guinea transmitted CJD to entire populations. And trauma may also be a trigger. The brains of the hockey and football players who died or suicided and were found to have Chronic Traumatic Encephalopathy have excessive amounts of tau protein and tau tangles in their brains. This research has been published by Dr. Ann McKee the Boston researcher who was interviewed on CBC “The National” several months ago.

Is There a Cure for Neurodegenerative Diseases

Can anything help prevent or slow the seemingly inevitable transformation of normal protein into self-replicating nerve-killing prions? Prusiner’s research group is now dedicated to testing new drugs on mouse models of neurodegenerative diseases that affect humans. They have had some success but have found that prions have the ability to mutate to survive the drugs. This suggests that as with HIV, multiple and changing drugs will be the rule rather than the exception. Prusiner, when asked, replied that clinical treatment is likely 20 years off... at this a depressive quiet settled over the room.

However, there is hope. Since the prion-forming proteins are found in all of us and transform in increasing amounts with age (and are thus the likely cause of normal “senility”) transformation to prions is likely part of normal ageing. Ageing is the result of many things including the decreasing length of telomers. As cells divide the telomeres which are small bits on the end of each strand of DNA (like the bits on the end of shoelaces that stop them from revelling) get shorter. When they are too short the cells can’t divide anymore and regeneration is no longer possible. Cells are also very sensitive to oxidative stress. It turns out that telomere length is very sensitive to oxidative stress and that a change of diet and lifestyle at any age can make them stop shortening which is bad or even get longer which is good (as long as they don’t get too long which causes cells to become immortal and cancerous). As in all things, it seems moderation is preferred.

Lifestyle Changes Decrease Risk of Alzheimer's Disease

And what are those diet and lifestyle changes that help? Those we discuss in the D&L group: moderate exercise, restrained eating, a Mediterranean diet of real food with lots, vegetables, whole grains, healthy proteins and good oils and good stress management skills including meditation. Think “Blue Zones” by Dan Buettner. Here is Dan Buettner's TedTalk: How to live to be 100+.

We know that a healthy diet and behaviours prevent and ameliorate many medical conditions such as heart disease, diabetes, high blood pressure and others. In the D&L group, Alzheimer’s Disease was included as being among the conditions impacted by lifestyle but at the time, I didn’t have the research to support this claim.

The prion theory of dementia could explain one mechanism of why diet and lifestyle are so important. To read more on the prion story I recommend the Blogspot of Canadian scientist Larry Moran.

Author: Eleanor (Ellie) Stein MD FRCP(C)

I am a psychiatrist with a small private practice in Calgary and am an assistant clinical professor in the faculty of medicine at the University of Calgary. Since 2000, I have worked with over 1000 patients, all with ME/CFS, FM and ES. My passion for this field comes from my own struggle with these diseases, my desire to improve my health and then pass on what I learn. My goal is for every patient in Canada to have access to respectful, effective health care within the publicly funded system. If you are looking for help and resources to help combat ME/CFS, FM and ES, see my guides and webinar.

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