Certain words tend to go together in English (so-called collocations), whilst other words rarely occur in close proximity to certain other words. A few collocations you rarely see are 'geriatric junkies', 'flower-power pensioners' and 'substance-abusing septuagenarians', but these were all in an article I spotted in The Times yesterday (it was a hard copy of the newspaper that I was reading in a coffee bar; unfortunately I can't link to it as you have to pay to access the Times' website these days).
Apparently, Germany has a problem with so-called 'opium grandpas' (a soundbite which sounds much better and wittier in German, since the word for grandpa is Opi). These are people who took full part in the Swinging Sixties and have not forsaken the lifestyle of that era. Improvements in healthcare means that drug users are living longer, but drug-related prosecutions of the over-60s have increased significantly too - they have more than doubled in the past decade in the state of North-Rhine Westphalia.
Here's a Spiegel article on the subject (in German).