Even though there is just as good of a possibility that it was a drug overdose, to make the presumption that drugs and alcohol go hand in hand must be based on personal experience because it's not the way I saw it when I partied through high school and a couple years after high school.
I can't even count the number of times we drank alcohol on my hands. Conversely, most people that didn't do drugs in school drank alcohol instead.
So by saying that people who do drugs also drink alcohol would mean that the people who drink alcohol also use drugs. If that's the case, then the war on drugs is an even bigger failure than I thought because there are a lot of people that drink.