Alzheimer's disease could actually be a collection of diseases that should be treated with a variety of different approaches. Distinct disorders that eventually lead to neurodegeneration need to be classified and treated separately, suggest researchers at the Hebrew University of Jerusalem's Faculty of Medicine.
Prion disorders like Alzheimer's and Parkinsons result from a protein-folding gone amiss. This has been noticed to appear sporadically or as an inherited mutation-linked disorder. In the former, the appearance of symptoms is later.
The researchers were looking into some aspects of the mutation-linked diseases like the similar time frames of apparently distinct disorders. And why the symptoms only begin to show late in life.
The international research team was led by professor Ehud Cohen and Dr Tziona Ben-Gedalya at The Institute for Medical Research Israel - Canada (IMRIC) in the Hebrew University's Faculty of Medicine.
Since neurodegenerative disorders arise from aberrant protein folding, the team postulated that age probably affects the activity of proteins needed to help other proteins fold properly.
They found that the development of Alzheimer's disease in certain families, and of a familial prion disorder in other families, both originate from malfunction of the protein "cyclophilin B".
However, the mechanism leading to Alzheimer's disease in individuals with these mutations is different to that of the disease's emergence in patients with other mutations.
According to professor Ehud Cohen: "This study provides important new insights: first, it shows that the development of distinct neurodegenerative disorders stems from a similar mechanism. More importantly, it indicates that Alzheimer's disease can emanate from more than one mechanism, suggesting that it is actually a collection of diseases that should be classified."
Cohen blames the lack of an efficient therapy on the clubbing together of patients with distinct disorders. It is essential to carefully characterise and classify the mechanisms that underlie Alzheimer's disease, in order to allow for the development of novel therapies that can be prescribed to the individual patient according to their relevant disease sub-type, he says.
Alzheimer's affects millions of people around the world. In 2010, there were between 21 and 35 million people worldwide with the disease.
Research has pointed to a continued build up of misfolded proteins leading to plaque and a tangle in the brain, as a result of which brain cells die. Blocking the pathways to this brain cell death has been the focus of drug development. However, most drugs tested on animals have shown up undesired side-effects.
Interestingly, in 2014 scientists at Washington university had found that schizophrenia is a combination of eight distinct disorders linked to gene mutations with their own separate symptoms.