so knowing keffals and his lust for stretching the truth i decided to look into what exactly psychomotor retardation is. while he is correct about it being a symptom of major depression. it is also connected to bipolar (the depression phase) and anxiety disorder as well as schizophrenia. it is also a side effect of taking benzos. it can also apparently get so bad that you need to be put in a nursing home but that seems to mainly be for people who are already suffering from other mental issues as well.
the wikipedia page talking about it lists some examples that seem to imply that many troons are in fact retarded.