IIRC it was disabilities that resulted in institutionalizing. I mean, sure, your depression could be so bad it makes you suicidal - but the Nazis didn’t exactly have a problem with you killing yourself.

It was people with intellectual disabilities, physical disabilities, and disruptive mental disorders. Down Syndrome, Fragile x, quadriplegics, cystic fibrosis, schizophrenia, severe ASD, etc. Almost always things that have obvious changes to “normal” behavior, intellect, and appearance.

However, I will say the modern day list of disability has grown, and I would strongly suspect that if the Nazis of Germany could get their hands on modner medical records and purge far more things, they would not have hesitated to do so.