5 scariest mental conditions

1. The "Cotard's syndrome".
   
   This makes people belive they are actually dead. These people are absolutely convinced that they just don't exist or have iner organs. They look completely normal as i understand, but in their head they are absolutely certain they are not breathing.
2. The "Capgras syndrome".
   
   People who have this think that people who are close to them, so i am guessing family most, is replaced by an impostor. People will completely act normal to them but will be 100% sure that it's someone pretending to be them.
3. The "Anton-Babinski syndrome".
   Okay, this somehow doesn't make sense but it's how it is. People suffering from this, are completely blind, they can't see a thing, but somehow not know they are. They would walk, not see a thing, run into walls, cars, everything that comes their way but still not realize they are blind. If you ask them, they deny it. It can be related to head-injuries.
4. "Apotemnophilia".
   Okay, people suffering from this are completely healthy people, look completely normal, but really want to chop their own arms and legs. The scary thing is, they will look like completely normal and functional people, talking to you normally, but on a side have a wish to chop their own body parts. I don't know how this comes to a person.
5. "Fatal familial insomnia".
   
   This is a condition that doesn't have a cure as far as we know. It makes it impossible for a person's brain to go to sleep. Nothing will help you, nor sleeping pills, or trying to relax, nothing helps, you just aren't able to go to sleep. People who have this, are most common to stay awake till they die. It's very rare and i don't know how people deal with this.

Alright, i didn't want to give the link right away, simply to make you read the whole thing. xD
5 Scariest Mental Conditions - Dean Leysen. I really wanted to share this, i have read about this on the internet and i figured he would have to make a video about at least some of them and as i figured, he has.

I don't even know what to think of these... I am not sure which one is the most scariest or most hard to deal with, but i think the last one is.
As i understood Dean, the first 4 conditions, people suffering from it, don't know they have a disease and that it's not really normal. People with insomnia are aware and aware that they can't sleep and just have to go through their whole life awake. What do you think?
All of these are just terryfying, especially if you have no idea who may have it. I think all of these are rare and i am not sure in which part of the world they are most common but i guess it doesn't really matter...