You are right to be concerned about how marijuana affects people who live with depression and bipolar disorder—especially younger people.
Using marijuana can certainly contribute to or worsen depression. Low motivation, fatigue, and withdrawal from positive activities are central features of depression and marijuana can worsen each of those problems. Some people do say that marijuana dulls anxiety or negative feelings. But it also dulls energy and motivation. And we know that activation and engagement are key parts of recovery from depression.
Marijuana can be even more troublesome for people—especially younger people—who live with bipolar disorder. In addition to worsening depression, marijuana can increase the likelihood of experiencing symptoms of psychosis—like hallucinations or paranoid ideas. In younger people who are at higher risk for bipolar disorder or schizophrenia, using marijuana increases the chances of developing a severe or disabling mental illness.
You’ll want to express your concerns to your husband in a way that feels caring rather than confrontational. If you talk to him about negative effects of marijuana use, the old advice about “I statements” definitely applies. You can say things like: “I notice that you seem less active and more withdrawn when you use marijuana” or “I’m concerned that using marijuana keeps you from doing positive things that would help you to feel better.”
