Caption: The protein tau (green) aggregates abnormally in a brain cell (blue). Tau spills out of the cell and enters the bloodstream (red). Research shows that antibodies (blue) can capture tau in the blood that reflect its levels in the brain. Credit: Sara Moser
Age can bring moments of forgetfulness. It can also bring concern that the forgetfulness might be a sign of early Alzheimer’s disease. For those who decide to have it checked out, doctors are likely to administer brief memory exams to assess the situation, and medical tests to search for causes of memory loss. Brain imaging and spinal taps can also help to look for signs of the disease. But an absolutely definitive diagnosis of Alzheimer’s disease is only possible today by examining a person’s brain postmortem. A need exists for a simple, less-invasive test to diagnose Alzheimer’s disease and similar neurodegenerative conditions in living people, perhaps even before memory loss becomes obvious.
One answer may lie in a protein called tau, which accumulates in abnormal tangles in the brains of people with Alzheimer’s disease and other “tauopathy” disorders. In recent years, researchers have been busy designing an antibody to target tau in hopes that this immunotherapy approach might slow or even reverse Alzheimer’s devastating symptoms, with promising early results in mice [1, 2]. Now, an NIH-funded research team that developed one such antibody have found it might also open the door to a simple blood test .
Caption: This international “Big Data” study involved hundreds of researchers in 22 countries (red).
It’s estimated that about 10 percent of the world’s population either has type 2 diabetes (T2D) or will develop the disease during their lives . Type 2 diabetes (formerly called “adult-onset”) happens when the body doesn’t produce or use insulin properly, causing glucose levels to rise. While diet and exercise are critical contributory factors to this potentially devastating disease, genetic factors are also important. In fact, over the last decade alone, studies have turned up more than 80 genetic regions that contribute to T2D risk, with much more still to be discovered.
Now, a major international effort, which includes work from my own NIH intramural research laboratory, has published new data that accelerate understanding of how a person’s genetic background contributes to T2D risk. The new study, reported in Nature and unprecedented in its investigative scale and scope, pulled together the largest-ever inventory of DNA sequence changes involved in T2D, and compared their distribution in people from around the world . This “Big Data” strategy has already yielded important new insights into the biology underlying the disease, some of which may yield novel approaches to diabetes treatment and prevention.
Caption: PET scan images show distribution of tau (top panel) and beta-amyloid (bottom panel) across a brain with early Alzheimer’s disease. Red indicates highest levels of protein binding, dark blue the lowest, yellows and oranges indicate moderate binding. Credit: Brier et al., Sci Transl Med
In people with Alzheimer’s disease, changes in the brain begin many years before the first sign of memory problems. Those changes include the gradual accumulation of beta-amyloid peptides and tau proteins, which form plaques and tangles that are considered hallmarks of the disease. While amyloid plaques have received much attention as an early indicator of disease, until very recently there hadn’t been any way during life to measure the buildup of tau protein in the brain. As a result, much less is known about the timing and distribution of tau tangles and its relationship to memory loss.
Now, in a study published in Science Translational Medicine, an NIH-supported research team has produced some of the first maps showing where tau proteins build up in the brains of people with early Alzheimer’s disease . The new findings suggest that while beta-amyloid remains a reliable early sign of Alzheimer’s disease, tau may be a more informative predictor of a person’s cognitive decline and potential response to treatment.
Credit: Jane Ades, National Human Genome Research Institute, NIH
Type 2 diabetes (T2D) tends to run in families, and over the last five years the application of genomic technologies has led to discovery of more than 60 specific DNA variants that contribute to risk. My own research laboratory at NIH has played a significant role in this adventure. But this approach doesn’t just provide predictions of risk; it may also provide a path to developing new ways of treating and preventing this serious, chronic disease that affects about 26 million Americans.
In an unprecedented effort aimed at finding and validating new therapeutic targets for T2D, an international team led by NIH-funded researchers recently analyzed the DNA of about 150,000 people across five different ancestry groups. Their work uncovered a set of 12 rare mutations in the SLC30A8 gene that appear to provide powerful protection against T2D, reducing risk about 65%—even in the face of obesity and other risk factors for the disease .
Caption: Lack of efficacy currently accounts for more than half of all drug failures in Phase II clinical studies (left). If AMP’s target validation efforts improve efficacy by 90% (right), the success rate will rise significantly.
It would seem like there’s never been a better time for drug development. Recent advances in genomics, proteomics, imaging, and other technologies have led to the discovery of more than a thousand risk factors for common diseases—biological changes that ought to hold promise as targets for drugs.
But this deluge of new opportunities has to be put in context: drug development is a terribly difficult business. To the dismay of researchers, drug companies, and patients alike, the vast majority of drugs entering the development pipeline fall by the wayside. The most distressing failures occur when a drug is found to be ineffective in the later stages of development—in Phase II or Phase III clinical studies—after years of work and millions of dollars have already been spent . Why is this happening? One major reason is that we’re not selecting the right biological changes to target from the start.