I'd imagine they are likely to be more of an issue too in the future, for longer term or more risky missions to Mars/etc. NASA try to select people who are highly stable as astronauts (used to be test pilots), but when the mission only has a 25% chance of getting you home, or involves you living on Mars for a year in a garden shed, then the people who would want to volunteer are going to tend to be mentally off to begin with.

I assume they've thought of this, even for lunar missions or ISS - I wonder what the protocol is? Do they bring handcuffs? Sedatives?