Alzheimer’s Research U.K. calls for increased investment in Alzheimer’s drug trials after a comprehensive study of all of the clinical trials for Alzheimer’s drugs in the U.S. highlighted a very high failure rate of the drugs being tested. The study, published in Alzheimer’s Research and Therapy, found that 99.6% of trials of potential Alzheimer’s treatments aimed at preventing, curing or improving the symptoms of the disease failed or were discontinued.

The study was conducted by the Cleveland Clinic Lou Ruvo Center for Brain Health and the Touro University Nevada College of Osteopathic Medicine. The researchers used clinicaltrials.gov to compile a database of all Alzheimer’s drug trials in the U.S. in the past decade. They then used the database to determine the outcome of trials at the three clinical phases and for drugs targeting various different mechanisms thought to contribute toward the disease.

The trial was deemed to have failed if there was no difference in symptoms between people who were treated with the drug versus the placebo, or if the side-effects were too severe to continue with the drug. The study found that the vast majority of drugs in all three phases of clinical testing failed during 2002 to 2012. This includes treatments aimed at reducing the levels of the hallmark proteins amyloid and tau, which are present in abnormal formations in the brain in people with Alzheimer’s. Of 244 compounds that were assessed over the ten-year period, only one was approved for marketing.

The study also took into account treatments which still are being tested. The authors note that there are very few drugs currently being tested, with only 23 compounds in the final phase of testing. There are 108 ongoing trials for Alzheimer’s drugs compared to 1438 trials for cancer drugs.

Dr. Simon Ridley, head of Research at Alzheimer’s Research U.K., said, “This study adds to other analyses showing high levels of failure of trials for Alzheimer’s drugs. Whilst the failure rate of clinical trials for cancer also is quite high, at 81%, the 99.6% failure rate in Alzheimer’s disease trials is especially troubling. Alzheimer’s disease is the most common form of dementia, which affects over 820,000 people in the U.K. and costs the economy $3.9 billion a year.

“There are multiple genetic and environmental risk factors for Alzheimer’s, making drug trials for the disease particularly challenging,” said Ridley. “People with Alzheimer’s often are diagnosed relatively late in the disease process which also means that the best window of opportunity for treatment may have passed. The rising numbers of people with dementia, along with the devastating effect that it has on those affected, mean that despite these setbacks we have to keep dementia at the forefront of clinical trials.”

Ridley continued, “The authors of the study highlight a worrying decline in the number of clinical trials for Alzheimer’s treatments in more recent years. There is a danger that the high failure rates of trials in the past will discourage pharmaceutical companies from investing in dementia research. We need to use this data to understand the reasons behind the discontinuation of these trials and address those issues. Pharmaceutical companies and other industries need to commit to continued investment in drug development and clinical trials in order to achieve a breakthrough in treating Alzheimer’s and other dementias.

“Alzheimer’s Research U.K. continually is working to reignite R&D in dementia, to put new treatments into the hands of those who so desperately need them,” said Ridley. “We are implementing a number of important initiatives, including funding a network of Drug Discovery Institutes and being a part of the Dementia Consortium in partnership with MRC Technology and the pharmaceutical companies Eisai and Lilly. The only way we will successfully defeat dementia is to continue with high-quality, innovative research, improve links with industry and increase investment in clinical trials.”