At the same time the DSM collapsed 3 Autism diagnoses into 1, it split OCD from Anxiety Disorder, into completely different chapters even. This is because of the parts of the brain that seem to be involved (the amygdala for anxiety and the cingulate gyrus for OCD.
I’m curious about it because one of the two principle criteria for Autism, restricted and repetitive behavior (RRB), can appear the same as OCD. This is particularly relevant to one case in my family.
I was digging into it yesterday and it turns out the cingulate gyrus is closely connected to the limbic system, with the amygdala on the end of the loop. Anxiety involves dysfunctional feelings of fear whole OCD involves processing of fear in dysfunctional ways. In anxiety one might not even know what specifically one is afraid of, while in OCD one obsesses over a fear/problem, or does the same thing repeatedly to try and dispell it.
Then I was looking into autism and one study found less amygdala (fear center) activation than average. This got me looking at the drugs used to treat them: SSRI for OCD and risperdone for ASD (risperdone addresses dopamine known for pleasure signalling). So the difference between ASD and OCD could be that OCD RRBs are about escaping fear, while ASD RRBs pursue reward.
It’s like trying to classify the lesser panda. It looks like a racoon or maybe a lemur, but it’s called a panda, and is a great panda even a bear? We looks for clues in appearance and response to medicine but the structures and functions of the brain are elusive. P.