One of the most powerful characterizations in The Lord of the Rings is the addictive nature of the Ring. The way it slowly but powerfully makes you prioritize it above everything else, never exerting obvious control over you but never letting go either. Obviously, anyone who reads the books or sees the movies will quickly draw connections to real-world addictions, like drugs.
Did Tolkien have any experience, personal or through his friends or family, of addiction? Was he drawing inspiration from a friend's battle with opium, for example, or morphine? Many of the harder drugs that people associate with Gollum today (e.g. "he looks like a meth addict") didn't exist then, and I know Tolkien wasn't a fan of direct allegory, but there were still plenty of addictive substances and behaviors that could have inspired him to create a character like Gollum or a power like the Ring's.
Was Tolkien drawing upon any personal experience when he developed the influence of the Ring, or was it purely an abstract exploration of power and greed?