by Emma Davies, Farming Connect Knowledge Exchange Hub, IBERS Aberystwyth University
ALzHeimer’S disease (AD) is a chronic neurodegenerative disease that affects millions of people worldwide. While the disease mainly progresses due to increasing age, some causes can be genetic, causing disease in young people.
The symptoms of AD begin with general memory loss, but can become devastating, with patients having significant problems with short and long-term memory. This can extend to being unable to recognise objects, places or even family members, and difficulty performing tasks such as talking, eating and walking.
While animal models are invaluable in helping us understand the mechanisms of complex diseases, translating findings from animal models such as rodents into human research can be very challenging. This is because rodent brains aren’t structured and don’t function in the same way as ours. Also, because rodents have short lives and don’t naturally develop AD, transgenic models, where animals are given a specific copy of a gene need to be used. This results in the model having one feature, but not the whole complex disease, which means developing treatments is very difficult.
Sheep can help us overcome these challenges as they have long lives, allowing researchers to investigate the mechanisms of ageing, and they have brains that are comparatively similar to our own. most importantly, old sheep have been found to naturally develop the same brain pathology as those people with AD, which means their condition is more reflective of AD and transgenic animals aren’t needed, allowing treatments to be investigated more robustly.
Because AD primarily affects cognitive function, it’s vital to know if treatments will prevent the deterioration or enhance the retrieval of cognitive abilities. However, because research has been primarily conducted in rodents, there aren’t any cognitive tasks for testing short- term and spatial memory in sheep.
We already know that sheep have excellent memories and advanced face recognition abilities as they can remember over fifty different sheep faces for two years, even after long periods of separation. While this may be expected as sheep live in flocks, impressively, sheep can also learn and remember complex images of human faces and can determine whether they are happy or angry.
researchers at Aberystwyth University are developing cognitive tasks for sheep, using discriminative tasks with computer images, which are comparable with those tests used for humans, to test memory and other cognitive functions. This will allow AD research, including therapy development, to be translated more effectively into humans.
“Sheep have excellent memories and advanced face recognition abilities
as they can remember over fifty different sheep faces for two years, even after long periods of separation.”