This study was published in the Journal of Drug & Alcohol Abuse in April 2021, and compared veterans (514, 90% male) & non-veterans (2758, 41% male) in the Illinois Medical Cannabis Patient Program. All participants were age 60 or above.
This study was primarily focused on determining differences between veteran & non-veterans in the Illinois program, but it did reach one significant result relating to the veterans that used cannabis:
"Veterans also reported desirable health outcomes of cannabis use for pain, sleep quality, health conditions, and quality of life."
The abstract of the published paper is here.