First, Dr Donna J Cross saw Alzheimer's rob her grandmother of her independence, personality, and ultimately her life.

Now the disease has taken hold of her father-in-law's brain, who now faces the same slow and heartbreaking decline. 

It may be too late for them, but Dr Cross wants to save the millions more diagnosed with the mind-wasting disease.

She believes she's on the cusp of a breakthrough after a repurposed cancer drug caused the 'complete reversal' of cognitive decline in mice with Alzheimer's.