I think it's the ADHD response to depression and anxiety. When you find it hard to develop good self-care habits that come naturally to others even in times of sadness or stress, an overwhelming sense of nihilism or fear can make even simple tasks seem far too daunting.

It's part of executive dysfunction. It's when the signal that takes you from "I want to do the thing" to "I'm actively doing the thing" never fires off. It happens in adhd and depression mostly, but not exclusively.

it’s the middle of the venn diagram.

Maybe. But also applies for depression.