It might one day be possible to gene-edit brain cells to prevent Alzheimer’s disease. Researchers have discovered that altering a key gene in nerve cells reduces the formation of a protein associated with the disease, though so far this has only been done in a dish.

Alzheimer’s is the main cause of dementia and the risk rises sharply as we grow old. Around 1 in 4 people aged over 90 have it.

The cause of Alzheimer’s still isn’t fully understood , but the leading hypothesis is …