Mental illness is not like physical illness in that other people can't catch it. But the people around a mentally ill person are affected, and have to learn their own coping mechanisms.
Those are offered by the National Alliance on Mental Illness (NAMI) in a free training course called Family-to-Family. Our monthly segment with NAMI Southern Oregon covered Family-to-Family earlier this year. Several people who went through the training report on its effects on them, and on the people they know with mental illness.