Scientists at Dongguk University successfully treated Alzheimer’s disease in mice using the gene-editing tool CRISPR-Cas9. They used the tool to edit out the Alzheimer’s causing gene in the mice, thereby improving their memory and other cognitive functions. While this is only a first step and much research remains to be done, these promising results put gene therapy on the map of possible treatments for Alzheimer’s.

As Alzheimer’s disease continues to elude the efforts of modern medicine, scientists turn to gene-editing technology to treat, or ‘manage’ it. Alzheimer’s is commonly associated with the BACE 1 gene, which drives the production of amyloid-β proteins in the brain. In the brains of Alzheimer’s patients, this protein accumulates on the outsides of neurons or nerve cells as “plaque,” and is thought to be one of the main causes of the disease. Using “DNA scissors” called CRISPR-Cas9, which can cut out a specified part of a DNA sequence, Dr. Jongpil Kim and his colleagues from Korea (Dongguk University) and the USA attempted to edit out the BACE 1 gene in the neurons of the adult mouse brain.

Theirs is the first in vivo attempt (using cells inside living mice) to test the effectiveness of CRISPR-Cas9 in stopping Alzheimer’s progression. Their ultimate ambition—like that of many others in the field—is to develop treatments for different forms of dementia, which would dramatically improve patients’ quality of life. “We aimed to see whether CRISPR-Cas9, one of the latest developments in biotechnology, can open up a new direction for treating dementia, which is, at present, considered an incurable disease,” Dr. Kim says.

Their results indeed look promising. Within 8 to 12 weeks of treatment with the CRISPR-Cas9 technology, the plaque surrounding affected neurons in the mice dramatically decreased and their cognitive functions improved substantially. The mice also showed better associative learning and spatial working memory. Further, there was no evidence of increasing mutations in other, non-targeted parts of the genome, suggesting minimal side-effects.

All this indicates the huge potential of gene editing technologies to treat neurodegenerative diseases: by removing faulty genes at their source, disease progression can be halted, or even reversed, in just a few weeks.

The authors advise caution, however, as gene editing cannot be undone. In Dr. Kim’s words, one must ensure that “no detrimental, and potentially very rare, genomic alterations are caused”. Thus, this technique requires much more research before it can be applied to human subjects.