Understanding Transmissible Dementia: The Science Behind Creutzfeldt-Jakob and Alzheimer's Disease

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• Prion Disease Basics: Protein Misfolding in CJD
• How CJD Spreads Between Humans and Animals
• Historical Evidence: Ritual Cannibalism and CJD Transmission
• Shocking 40-Year Incubation Periods in CJD
• Similarities Between CJD and Alzheimer's Disease Mechanisms
• Diagnostic Implications for Neurodegenerative Diseases
• Full Transcript

Prion Disease Basics: Protein Misfolding in CJD

Dr. Sebastian Brandner, MD, clarifies that Creutzfeldt-Jakob disease (CJD) belongs to the same category of neurodegenerative disorders as Alzheimer's and Parkinson's. Like these more common dementias, CJD involves the misfolding of brain proteins that clump together, ultimately killing neurons. However, CJD's prion proteins have unique transmissible properties that set them apart.

How CJD Spreads Between Humans and Animals

Dr. Sebastian Brandner, MD, explains CJD's rare but proven transmission pathways. While spontaneous cases dominate, Dr. Brandner details how bovine spongiform encephalopathy (BSE or "mad cow disease") demonstrated cross-species transmission from cattle to humans. Experimental studies also confirm transmission between sheep and other mammals, establishing prion diseases as uniquely infectious among neurodegenerative conditions.

Historical Evidence: Ritual Cannibalism and CJD Transmission

Dr. Sebastian Brandner, MD, recounts the pivotal Papua New Guinea case study where ritual endocannibalism - consuming deceased relatives' brain tissue during funeral rites - created a CJD epidemic. "One initial case spread through the community over generations," notes Dr. Brandner, with Australian researchers like Dr. Daniel Gajdusek later proving the infectious protein mechanism. This led to banning the practice and eventual decline in cases.

Shocking 40-Year Incubation Periods in CJD

The neuropathologist reveals an extraordinary 2003 autopsy case proving CJD's decades-long latency. "A patient exposed in the 1960s developed symptoms only in 2003," Dr. Brandner tells Dr. Anton Titov, MD, emphasizing how this 40-year incubation period complicates disease tracking. Such extended timelines explain why new cases emerged long after Papua New Guinea's cannibalism prohibition.

Similarities Between CJD and Alzheimer's Disease Mechanisms

Dr. Sebastian Brandner, MD, draws critical parallels between CJD and Alzheimer's pathology. Both involve misfolded proteins (prions vs. beta-amyloid) that aggregate destructively in brain tissue. While Alzheimer's isn't currently considered transmissible, Dr. Brandner's research on protein propagation mechanisms offers insights that could advance understanding of all protein-misfolding dementias.

Diagnostic Implications for Neurodegenerative Diseases

Dr. Sebastian Brandner, MD's findings revolutionize how clinicians approach dementia diagnosis. Dr. Sebastian Brandner, MD, emphasizes that CJD's transmissibility requires heightened vigilance with neurological histories, especially regarding past exposures. His work also suggests potential overlaps in therapeutic strategies targeting protein misfolding across Alzheimer's, Parkinson's and prion diseases.

Full Transcript

Dr. Anton Titov, MD: You have done important research on prion diseases. It is CJD, Creutzfeldt-Jakob disease. What are your findings? What are the implications for the diagnostics, prevention and treatment of prion disease?

Dr. Sebastian Brandner, MD: First of all, we need to clarify a few issues around CJD, Creutzfeldt-Jakob disease. CJD in its usual form is spontaneous. It is a sporadically occurring neurodegenerative disease. It is like Alzheimer's disease, or like Parkinson's disease.

Dr. Sebastian Brandner, MD: Like in Alzheimer's disease, like in Parkinson's disease, in CJD there is an incorrect folding of the brain protein. It turns into something that clamps together. It essentially starts killing the brain cells. That's what happens in CJD.

This is a reason why CJD has become such a hot topic. A long time ago it was discovered that CJD is actually transmissible between humans. Later it was also shown that Creutzfeldt-Jakob disease is transmissible between different other species.

That included infection transmission from cattle into humans. That's BSE [Bovine Spongiform Encephalopathy] epidemics. CJD could be transmitted from sheep into other species, usually experimentally.

Dr. Sebastian Brandner, MD: The first convincing demonstration that CJD is a human transmissible neurodegenerative disease comes from indigenous population in Papua New Guinea. They had a ritual to eat body parts of relatives. This was part of the festivities when someone died.

Body parts were dissected and distributed to the community. That habit probably survived for many hundreds of years in this population. Similarly to other cases of Creutzfeldt-Jakob disease this happened.

One of these patients may have just accidentally have developed CJD. Then the person died. These body parts were then distributed in the community. It takes many years to develop CJD.

These patients received and ate these body parts. They developed CJD themselves. After that the incubation time of Creutzfeldt-Jakob disease was shorter and shorter.

In the 1950s and 1960s the Australian government came in. It looked at the situation. Because it was thought to be a form of slow virus disease. Because it took a long time for brain degeneration to develop.

CJD, Creutzfeldt-Jakob disease caused all this shaking and ataxia. It is a gait disorder. Dr. Daniel Gajdusek discovered that a brain protein itself can be transmitted. Abnormal protein can cause the disease in other humans.

When this was recognized, then obviously all this habit or eating dead relatives was banned. Very soon the big epidemics of CJD stopped. But patients still were developing new CJD cases many years later.

The longest incubation time for Creutzfeldt-Jakob disease we recently observed was 40 years. Someone who had in the 1960s participated in one of human body parts feasts. That patient died in 2003. We did an autopsy.

Dr. Anton Titov, MD: So that was the first really good evidence for CJD transmissibility.

CJD, Creutzfeldt-Jakob disease, is usually spontaneous neurodegenerative disease. It is like Alzheimer’s disease, or Parkinson’s disease. In CJD a brain protein folds incorrectly into the form that kills the brain cells.