Hi Annoyedgrunt

In answer to your question, some psychologists say depression is learned helplessness in people and animals. Someone experiences a lot of situations in early life where they have no control so they learn that they can never change anything, even though as an adult, that is not entirely true.

Feel free anyone to shoot this definition down in flames, I'm not sure it's the full picture anyway, and maybe someone else can contribute. ...

Meanwhile I send warm hugs and wishes for whatever you're experiencing now.
Be kind to yourself, you deserve it.