Dr. Drew Says GLP-1 Drugs May Have Helped Nick Reiner, but Thinks Meth Played a Part in Murders

Nick Reiner's weight gain set him on a murderous path, but it didn't have to be that way ... just ask Dr. Drew. The good doctor points out a change in his medication could have sent him spiraling ... but Dr. Drew also asserts harder drugs may have spurred a homicidal mind state.

Dr. Drew joined us on "TMZ Live" Monday and discussed what he thinks actually sent Nick all the way over the edge ... "The kind of violence that was on display here to me still reads methamphetamine … I keep saying that over and over again."

Drew continued ... "When he was picked up, it's worth trying to understand: What part of town was he in? What was he doing there?"

Reiner was arrested in the Exposition Park neighborhood of L.A., not far from the USC campus, about 10 minutes south of downtown ... portions of the area are sketchy and are associated with drug dealing. LAPD Gang and Narcotics Division officers made the arrest.

Drew also addresses what we uncovered in our new documentary, "The Reiner Murders: What Really Happened" ... Nick's unravelling that resulted in the murders of his parents, Rob and Michele Reiner, is directly connected to his gaining weight.

Drew told us Nick likely would have benefited from being prescribed weight-loss drugs to counteract a common side effect of the anti-psychotic drugs he was taking.

Nick was stable on a cocktail of drugs until a month before the murders, when he complained to doctors about weight gain. His meds were changed, and sources say the new mix sent him into an erratic, dangerous state. We're told he had a complete break from reality at the time of the murders.

Dr. Drew says psychiatrists, particularly younger ones, are now prescribing patients GLP-1 drugs -- like Ozempic and Mounjaro -- as a way to counterbalance side effects from the other pills ... though he says it's a delicate balance.

In Nick's case, Dr. Drew says GLP-1 drugs may have helped ... and who knows where Nick, Rob, and Michele would be if the meds were never changed.