A flying start

The human brain has a similar number of nerve cells as there are stars in our galaxy. Recreating this complexity in the laboratory is impossible. Animals like worms, fruit flies and mice can help scientists understand features of diseases that are hard to study in people. We always strive to use alternatives to animal research wherever possible, but in some cases they allow scientists to gain important insight into the disease in a short period of time.

Even though animals like flies and mice have evolved for millions of years and look very different to humans, their genes remain surprisingly similar. An amazing 75% of genes linked to human diseases like cancer, heart disease and Alzheimer’s have related genes in the fruit fly. There are also similarities in the way the brain develops and how it regulates behaviour between flies and humans, making them a useful model for studying brain diseases.

Fly genes can be easily altered in the lab, allowing researchers to switch on and off genes that could be important in diseases that cause dementia. Flies bred with features of Alzheimer’s tend to move more slowly and live shorter lives. Flies engineered to have an altered form of the human tau protein, seen in Alzheimer’s and frontotemporal dementia, also have noticeable changes to their eyes. As flies develop these symptoms over a matter of days, rather than decades, they provide a quick and easy way for researchers to gain important insight into these diseases.

Mice also have similar genes to humans – 80% of all human genes have an equivalent in mice. Mice have been bred to show the characteristic build-up of proteins in the brain seen in human diseases, such as the clumping of a protein called alpha-synuclein in dementia with Lewy bodies. Researchers can then study in detail what happens in the mouse brain, to gain clues to what these proteins do and why they could be so damaging. While these findings are likely to be a more simplistic version of what happens in the human brain, these studies are an important step in the discovery of new targets for treatment.

Video courtesy of Dr. Danielle Diaper
Hirth Lab, King’s College London