Hypotheses. Alexithymia is not a symptom of autism. It’s a symptom of long term depression associated with autism.
When I was on antidepressants one of the first things I noticed about my mood change was that everything felt blunted. It wasn’t so much that my mood improved, it's almost like the antidepressants had made me feel slightly disconnected and disassociated from my own feelings. If you had asked me how I felt when on antidepressants I might have said I don’t know or I’m not sure a lot more than usual.
This was part of the function of the antidepressants. It allowed me to function.
It’s been suggested that a symptom of autism can be alexithymia. That something about the autistic makeup makes us less likely to be able to recognise our own feelings. I’m skeptical of this interpretation.
Have you ever heard about boiling a live frog? Bring the water up to boil quickly and the frog jumps out. Do it gradually and the frog will sit there and boil. Or people who live in houses with gas leaks who ignore it. How they become blind to the smell over time.
I suggest that alexithymia in autism is the same kind of thing. When people have experienced negative emotion, depresion, anxiety, constantly over years, to the point where they’ve developed a learned helplessness around the situations that evoke these feelings. That this can lead to alexithymia as a form of coping strategy. That this dissociation from one’s own feelings is infact a form of emotional numbness, a form of traumatic response to long term, situation linked, anxiety and depression.