them have alzheimer s. it s a diseaese that gradually destroys key areas of the brain involved in memory and understanding. but there are questions about the cost and safety of the new drug. our medical editor, fergus walsh, spoke exclusively to one of the patients on the trial. hello. are you all right, mr colley? hi, yes, thank you. i ve got your donanemab here for you. mike colley has alzheimer s disease, yet the 80 year old feels incredibly fortunate. i m one of the luckiest people you ll ever meet. just for this. that s because he s been on the global trial of donanemab for two years. he s come with his son for his monthly infusion, at this clinic in london. i seem to get more confident every day. and i m sure this is going to be successful. they ll get all the rubbish off the top of my brain and i ll be back to normality. i m very confident about that. i never thought that i would see my dad just so full of life again. you know, now we have hope and, two years ago, we d