WASHINGTON (WOWO) — An experimental Alzheimer’s drug that targets a key brain protein linked to the disease may help slow cognitive decline in people with early-stage Alzheimer’s, according to new research presented Tuesday.

The drug, called diranersen, works differently from currently approved Alzheimer’s treatments by reducing levels of tau, a protein that researchers believe plays a major role in the progression of the disease.

The findings, presented at the Alzheimer’s Association International Conference in London, suggest the drug not only lowered tau levels but also slowed worsening memory and thinking abilities in some study participants.

The study involved about 400 people with mild cognitive impairment or mild Alzheimer’s disease. Researchers said a larger clinical trial will be needed to determine whether the drug provides a meaningful benefit for patients.

“This is really quite promising if it were to hold up” in future testing, said Jessica Langbaum of the Banner Alzheimer’s Institute in Phoenix, who was not involved in the study.

Dr. Reisa Sperling of Mass General Brigham, who also was not involved in the research, urged caution while calling the findings significant for the field.

“This is early days,” Sperling said, adding that the results could encourage more research and investment into treatments aimed at tau.

Alzheimer’s disease affects more than 7 million Americans and tens of millions of people worldwide. Scientists believe the disease is driven in part by the buildup of two abnormal proteins in the brain: amyloid and tau.

Existing Alzheimer’s drugs, including lecanemab and donanemab, target amyloid plaques, the better-known protein buildup associated with the disease. Those treatments can modestly slow cognitive decline but do not stop Alzheimer’s progression.

Researchers believe amyloid buildup may eventually trigger changes in tau, causing the protein to form damaging tangles inside brain cells that contribute to memory loss and other symptoms.

Diranersen takes a different approach. Instead of trying to remove tau after it has accumulated, the drug uses a genetic technique called an antisense oligonucleotide to reduce production of the protein.

“If you lower tau production, you are lowering the amount of the abnormal tau that needs to be cleared by the microglia, by the clearance mechanism in the brain,” said Dr. Cath Mummery of University College London, who led the study. “And so you are enabling the normal clearance mechanism to have more capacity to clear the tau.”

Unlike current anti-amyloid treatments that are delivered through bloodstream infusions or injections, diranersen is injected into the fluid surrounding the spinal cord, providing a more direct route toward the brain.

Biogen and its partner Ionis Pharmaceuticals previously announced in May that the lowest dose tested in the study appeared to have the strongest effect. Researchers said that unexpected result meant the study did not achieve its planned goal of showing that higher doses produced greater benefits.

Despite that limitation, researchers said additional findings were encouraging.

Mummery said five of six brain tests showed that participants receiving diranersen experienced slower cognitive decline compared with those who received placebo injections.

In one test involving the lowest dose, researchers estimated the drug was associated with a 26% reduction in cognitive decline — a result Mummery said was approximately comparable to changes seen in earlier studies of amyloid-targeting drugs.

The study also found some side effects, including pain at the injection site and temporary confusion that developed several days after treatment and lasted about a week.

Researchers said there were no signs of brain inflammation, a serious potential side effect associated with some anti-amyloid Alzheimer’s treatments.

The new research is part of a broader effort to develop treatments that target tau.

The University of California, San Francisco, recently launched the Alzheimer’s Tau Platform, a National Institutes of Health-funded initiative designed to test multiple experimental tau treatments, both alone and in combination with existing amyloid therapies.

The first treatment being studied through that effort is AADvac1, a vaccine designed to train the immune system to recognize and target a specific portion of the tau protein, according to UCSF researchers.

Scientists are also investigating other possible approaches to Alzheimer’s treatment.

Researchers are studying whether the cholesterol-lowering drug obicetrapib could reduce Alzheimer’s-related protein buildup in people with genetic risk factors, including those who carry the APOE4 gene variant, which is associated with increased Alzheimer’s risk.

Other companies are working on technologies designed to help Alzheimer’s drugs reach the brain more effectively by crossing the blood-brain barrier, a protective system that limits what substances enter the brain.

Researchers say while diranersen and other emerging treatments remain experimental, the findings represent continued progress toward developing more effective ways to slow or prevent Alzheimer’s disease.