Moving on from the mice...

Humans are the only animals that develop Alzheimer's disease.  The brains of dogs sometimes develop plaques and tangles that resemble those of Alzheimer's disease, but this does not lead to cognitive decline.  This makes them a poor candidate for studying the disease.

While rodents also do not develop Alzheimer's disease, mice can be genetically modified to produce a disorder that resembles Alzheimer's disease in humans.  So they have carried the load for the more invasive biological studies of neurodegenerative diseases.  But mice are biologically and behaviorally very different from humans, and research results based on a "mouse model" of human epidemiology is sometimes challenged.  So are there other animal models that more closely resemble human physiology and behavior?

At the recent AAIC 2020 conference, some Japanese researchers proposed the marmoset as a better animal model.  Weighing less than a pound, the marmoset is a small South American monkey whose brain much more closely resembles humans than does the mouse.  The researchers learned to edit the marmoset's presenilin 1 gene.  This is one of three genes responsible for young onset Alzheimer's disease in humans.  

The researchers propose that using gene-edited marmosets in future Alzheimer's research will produce more reliable results. This is because: 

• They have complex social behaviors and sleep patterns that resemble ours. 
• Their metabolism and immune systems are also more similar to those in people than those in rodents.  
• They can live 10 to 15 years in captivity, and typically develop tau tangles and amyloid plaques as they age. 
• The sequence of amino acids in their beta amyloid is identical to that of humans. 
• Raising and maintaining research colonies is feasible because these primates are small and produce many offspring.

One thing not discussed in any presentation I've seen is resistance from animal rights groups to invasive neurological tests.  I have seen resistance to the use of mice in Alzheimer's research, so I wonder how long it will take for resistance to the use of primates to develop.