An experimental drug for Alzheimer’s disease prevention does not significantly affect cognitive decline, new research suggests.

However, the treatment did reduce markers of disease and curbed neurodegeneration in the brain.

These results led researchers to offer the drug, known as gantenerumab, to participants as part of an exploratory trial.

Scientists are continuing to monitor changes in measures of Alzheimer’s disease in those participants who are receiving the drug.

The drug's ability to shift multiple Alzheimer's biomarkers toward normal indicates that it is positively affecting the disease process

The DIAN-TU study evaluated the effects of two investigational drugs – gantenerumab, made by Roche and its US affiliate, Genentech, and solanezumab, made by Eli Lilly and Co – in people with a rare, inherited, early-onset form of Alzheimer’s.

It is known as dominantly inherited Alzheimer’s disease (DIAD) or autosomal dominant Alzheimer’s disease.

People with this form of the disease are born with a mutation that causes Alzheimer’s, and experience declines in memory and thinking skills starting as early as their 30s or 40s.

DIAD is estimated to represent less than 1% of cases.

Principal investigator Randall Bateman, director of DIAN-TU and the Charles F and Joanne Knight distinguished professor of neurology at Washington University, said: “Gantenerumab had a major impact on Alzheimer’s biomarkers.

“The drug’s ability to shift multiple Alzheimer’s biomarkers toward normal indicates that it is positively affecting the disease process.

“The effect was strong enough that we launched an open-label extension of the trial so participants have the opportunity to stay on the drug as we continue to study it.”

In the study, 144 people with DIAD received either gantenerumab or solanezumab or a placebo control for up to seven years.

Neither drug prevented or slowed cognitive decline in people who are nearly certain to develop Alzheimer’s due to genetic mutations.

Researchers were not able to determine effects on thinking and memory in participants who entered the study without symptoms, because they exhibited little to no decline in cognitive function.

The study also evaluated the effect of the drugs on molecular and cellular signs of Alzheimer’s disease.

According to the research published in Nature Medicine, gantenerumab showed potential benefit on these measures.

“Although the trial focuses on people with rare mutations, drugs that are successful in this population would be promising candidates for preventing or treating the forms of Alzheimer’s that occur more commonly in older adults,” Dr Bateman said.

“The destructive molecular and cellular processes in the brain are similar in both types of the disease.”