I just came across this notable new research paper authored by Sara Markowitz and Katie E. Leinenbach available for download from the National Bureau of Economic Research. Here is its abstract:
Suicide rates among older adults have been rising over time in the United States. At the same time, more individuals have been suffering with chronic pain and illness, which are often underlying risk factors for suicide. As self-medication with marijuana has become common, we ask whether access to legal marijuana for medical and recreational purposes reduces suicides rates among older individuals. We find that suicide rates among older age groups decline following the opening of recreational marijuana dispensaries, especially among older Whites, and middle-aged White males and females with low levels of education.