Why pick worry as a topic?
Indeed. One of the few benefits of anxiety is the creation of fictional worlds or alarming perspectives wherein writers can indulge and play out their fears. This may heal, it may exacerbate, I’m not sure. Nevertheless, a writer’s worries, which come in many flavours, are a boon to readers with similar tastes.
Your first choice is Wolf Solent by John Cowper Powys. What’s the flavour of worry here?