A new study found that the number of middle-aged and older adults using marijuana is on the rise. The analysis, based on the National Survey on Drug Use and Health, found that about 9% of adults between 50 and 65 had used cannabis in the last year, and about 3% of those 65 and older had.Any people are using marijuana for medical purposes, hopefully their doctors are aware of the medications being taken. However, if you are using marijuana and your doctors don’t know, you should tell them as soon as possible. They may be aware of potential marijuana-drug interactions.