One study highlights the need for larger clinical trials on Alzheimer's disease that occur much earlier

There is currently no medication that stops or inhibits Alzheimer's disease. Despite drug trials showing a reduction of plaque in the brain, the cognitive function of patients has not improved. Would the results be different if it was possible to design studies occurring much earlier in the disease before cognition was affected? This is what an international study, led by Lund University in Sweden, has attempted to facilitate. The results have now been published in Neurology.

Although several expensive drug trials for Alzheimer's disease in recent years have had negative results, early diagnosis of the disease has improved. Research is underway to develop simpler and less expensive methods, such as those involving biomarkers, to detect the disease at an early stage, before the patient exhibits symptoms.

One of the problems is that most drug trials are designed to evaluate the effect of anti-amyloid treatments on patients with dementia stage of the disease. At this point, the patient is already suffering from severe memory impairment, a beta-amyloid has accumulated in the brain for many years.

Understanding the link between amyloid pathology and cognition is important for badessing cognitive decline in people who do not yet have cognitive impairment. "

Philip Insel, PhD student at Lund University's Clinical Memory Research Unit and first author of the article

"Because the disease starts long before an individual has any symptoms, it is important to observe the process at a preclinical stage of the disease.We must also observe larger cohorts of people to get an reliable and reproducible result, "he continues.

For more than six years, researchers in an international study have studied cognition in preclinical Alzheimer's disease in 1,120 people without cognitive impairment. In this group, 350 showed signs of Alzheimer's disease.

The study participants were recruited from three continents in three relatively heterogeneous cohorts in Sweden (Lund / Malmö), North America (ADNI) and Australia (AIBL). Despite the differences between individuals in the groups, the researchers observed the same pattern of cognitive development in those who had beta amyloid in the brain.

The researchers carefully badyzed the evolution of various cognitive tests over time in pre-clinical Alzheimer's disease, and compared this to the results obtained in those with no evidence of amyloid pathology in the brain.

"If we could find out when Alzheimer's disease would begin to affect a person's cognition, it would be possible to design more effective drug trials at a much earlier stage well before the onset of Alzheimer's disease. of dementia, while we believe that the treatment will be effective, the most effective.

A possible explanation for the failure of previous trials may be that the disease has progressed too far and that patients at this advanced stage of the disease are being treated with a drug candidate targeting a protein already present in the brain for many years. years, "says Philip Insel.

"Our results show that drugs need to be tested on patients from the onset, at the pre-clinical stage of Alzheimer's disease, at least six years before the onset of symptoms." Future trial designers Drugs need to be prepared to carry out larger and longer tests than before, "says Niklas Mattsson. head of research team at Lund University.

"If we could find ways to slow down the development of Alzheimer's disease, it would bring great benefits to patients, their loved ones, and health care providers." It could also reduce the significant costs that society would incur. for public health care for patients with dementia, "he concludes.