What is a subtle sign that someone is not doing well mentally?

[Answered on Quora.com by Jason N.]

Well, there are a lot of different ways in which someone could be experiencing a decline in their state of mental health, each with its own set of symptoms, but if I were to choose just one that most accurately encapsulates most of them, it would probably be:

Withdrawing from engaging in activities they used to enjoy and/or isolating.

Worsening anxiety and/or depression that stems from a chemical imbalance, a major life stressor, or a recent trauma would likely all result in a person doing that.

Even the first break with reality seen in chronic conditions such as in schizophrenia would likely see a change in the way a person engages with the world, or lack thereof.

It’s sad, too. So many people get so offended when someone they know begins to pull away from them due to experiencing a decline in their mental health.

I have struggled with depression on and off throughout my life, and if I were missing 4 fingers on my right hand, I’d still be able to count the number of people who were still present after I began to isolate.