Yes, a diagnosis has to be established. Otherwise anyone 20 years old or more could request medical assistance in dying regardless of what has happened in their lives, such as a head injury or stroke. These aspects are already covered in large part by the advance directives, if the person has made them known. Medical assistance in dying can't be requested through advance directives.
What we're requesting is that a patient who has received a diagnosis of cognitive neurodegenerative disease be able to give advance directives specifically concerning medical assistance in dying.
All my colleagues agree that a precise diagnosis has to be given, whether it be of Alzheimer's disease, Parkinson's disease or Lewy body dementia, for example.