Researchers at the University of Texas San Antonio have found that low-dose THC, when paired with the anti-inflammatory drug celecoxib, showed promise in preventing Alzheimer’s development in mice. The combination preserved learning and memory, lowered neuroinflammation markers, and reduced hallmark brain pathology without the inflammatory signals seen with THC alone. Because both drugs are already FDA-approved, the team sees a clearer path toward clinical testing.
The study tested tetrahydrocannabinol, the main psychoactive compound in marijuana, alongside celecoxib, a selective COX-2 inhibitor commonly used for arthritis and pain. The two treatments were given daily to mice for 30 days, timed before any memory symptoms appeared to evaluate preventive effects. Researchers wanted to know whether the pairing could deliver benefits without the downsides linked to THC on its own.
Mice that received the combination showed measurable gains in cognition, learning, and memory compared with controls. Scientists also found reductions in neuroinflammation markers and less Alzheimer’s-related brain pathology. Those changes suggest the therapy affects the biological processes thought to drive the disease, not just short-term behavior.
THC by itself produced some of the same cognitive improvements, but it also raised inflammatory signals that could undermine long-term brain health. The combined low-dose approach avoided that spike in inflammation while keeping cognitive benefits intact. “What really mattered was behavior. If cognition is not improved, then the treatment doesn’t matter. And that’s where the combination clearly worked better than THC alone,” noted lead study author Chu Chen, Ph.D., professor in the Department of Cellular and Integrative Physiology.
Years of work helped the team understand why THC can be a double-edged sword in neurological conditions, and how celecoxib might blunt the negative response. “When THC is given, it unexpectedly increases COX-2 in the brain. That increase is closely associated with learning and memory impairment,” Chen said. Blocking that COX-2 rise appears to preserve the helpful, neuroprotective effects of THC while limiting harm.
Because both compounds are FDA-approved for human use, investigators say the findings could offer a “real advantage” in moving toward clinical trials. Future work will test whether the combination slows established disease or can even reverse deficits after symptoms appear. Those next steps will be critical to determine whether mouse results translate into meaningful human therapies.
Outside experts called the results encouraging and noted the growing link between inflammation and cognitive decline. Dr. Paul Saphier described the work as an “exciting breakthrough with a huge potential impact for patients and their families.” “Neurocognitive deterioration has been linked to conditions that cause inflammation within the brain — prior brain bleeds, strokes, tumors and infections,” he said, and “We also know that the buildup of the plaques related to Alzheimer’s [beta-amyloid plaques] are the result of chronic inflammation.”
“So, it makes sense that this combination therapy [might] help limit the production of this amyloid and thereby reduce the progression of the disease,” Saphier added, noting that the FDA approval status of the drugs is “encouraging,” and may “ultimately ease the availability for patients, if the trial proves successful.” “I look forward to the results of this trial, as well as any future trials that look at limiting the effects of chronic inflammation within the central nervous system”
