Early on set Alzheimers runs in my family, so I have a ~50% chance of inheriting in about 15 years time. I will likely explore this option if it becomes evident I have the gene (I can do a test). Having witnessed what it did to my Dad and Aunt. I'm obviously biased, but I think it's about as gruesome and terrifying a way to die as humanly possible.
My initial thoughts on people in there 20s being euthanised for depression are that I am not in favour of it all. In fact I am not in favour of it for depression or any condition that isnt terminal or causing constant, unbearable, incurable pain. Depression can be overcome or managed or mitigated. Not saying its easy or that everyone will overcome it, but whilst it's possible, theoretically or in practise, I don't think this should be an option that is provided by the health service. I work with people with schizophrenia, which is incurable (or at least currently deemed to be), which is obviously a demographic with high suicide rates and high depression rates, and even they can in many cases have a tolerable existence, and moments worth living for. I have seen other people who are so depressed that they are either psychotic or virtually comatose, and I have seen them get better. When they were in that state they couldn't write an article or speak to camera to explain eloquently why they wanted to die. They were barely able to mutter a sentence, let alone a coherent one. This reeks of EUPD or similiar to me, which health services are currently not great at treating, but it is treatable.