In my experience, most workplaces have at least one manager with a light-medium addiction problem (tends to be alcohol for olders, and marijuana for millenials). It might be hard to spot, but the best way to track it is the quality of decision making.
Unfortunatly, addiciton and other mental health problems are almost impossible for the firm to adress until its too late for everybody (disgrunted employees, missed business opportunities, etc). I hope this COVID crisis will make us more preventive regarding these issues.
Mental health issues may have no clear physiological cause. Even if there's a physiological aspect, it's unclear what the causes that condition. Depression, for example, we see low serotonin levels, but we don't know why the levels are low. In the case of addiction, the mechanism is clear. https://science.sciencemag.org/content/278/5335/45
Addiction issues are mental health issues because there is no reward; it is not a rational choice. It follows that people with addiction issues are either not informed enough to make a rational choice, irrational, or for some reason are unable to say no.
If the model were really this simple, relapse would be non-existent. I can't believe any former addicts would make a rational choice to relapse.
Unfortunatly, addiciton and other mental health problems are almost impossible for the firm to adress until its too late for everybody (disgrunted employees, missed business opportunities, etc). I hope this COVID crisis will make us more preventive regarding these issues.