Tangled Bank Studios, LLC
Francisco Lopera, Kenneth Kosik,
and Lucia Madrigal on horseback outside Medellín, Colombia, a region
where these neurologists have found the world's largest family with
hereditary Alzheimer's disease.
It’s easy to think that the mysteries of Alzheimer’s disease
will be revealed in the high-tech hallways of US medical centers and
research institutes. But new discoveries are coming from far-off places
like Medellín, Colombia, which may be ground zero for finding the
genetic basis of this dreaded neurodegenerative disease that strips
people of memories and destroys personalities.
For more than 25 years, I have worked with Dr.
Francisco Lopera of Medellín’s University of Antioquia in studying the
largest known family with inherited Alzheimer’s disease. Its family tree
goes back 300 hundred years.
Hundreds of individuals in this family are fated to get the disease.
Their symptoms usually develop between the ages of 45 and 50.
Studying this community has given us a clear
picture of Alzheimer’s in this genetic microcosm. We now know the gene,
called presenilin 1 (PSEN1), that is responsible for this family’s
disease. Knowing the gene mutation means we can predict which family
members will get Alzheimer’s. Knowing whom the disease will strike, and
when, offers a powerful basis for finding a treatment and determining if
it is effective. The Colombian family is now part of a large prevention
trial.While most of the family members with the PSEN1 variant develop Alzheimer’s disease before age 50, a few develop it later. We have recently discovered that these individuals carry a different genetic variant that provides some protection against the disease. This modifier gene can delay Alzheimer’s onset by as much eight to 10 years. But it doesn’t provide complete protection — we haven’t seen anyone with the PSEN1 mutation who escapes Alzheimer’s disease.
In a surprisingly improbable happenstance, another large family with a different genetic mutation that also causes Alzheimer’s at an early age lives in a nearby village. This gives us an opportunity to put our findings of a modifier gene to the test in a different genetic setting.
Obstacles remain
Despite more than 100 years of research, relatively little is known about Alzheimer’s disease. Experts still don’t have a fundamental understanding of the underlying biological and physiological changes of the disease or what drives them.The scope of the problem is daunting. Around the world, more than 40 million people are currently suffering from Alzheimer’s; more than 5 million of them live in the United States, and that number is projected to double as baby boomers age over the next 20 years. The disease already burdens our communities and our country: 15 million Americans provide care for a loved one with the disease, while Alzheimer’s health care costs exceed $200 billion a year in the US and are projected to surpass $1 trillion as the population ages.
The drug development process for Alzheimer’s disease is riddled with challenges. One issue for clinical trials is the inclusion of individuals misdiagnosed with Alzheimer’s disease. Including individuals with vascular dementia, Lewy body dementia, or even poorly understood forms of cognitive impairment — all of which can look like Alzheimer’s — can easily throw off a trial’s results. On the other hand, including those with advanced Alzheimer’s may also skew results because they may have lost too many brain cells to measurably respond to the therapy.
Researchers also face challenges when measuring trial outcomes, since they must quantify changes in the way a person thinks (cognition). Directly measuring cognition can be hard to do, so stand-ins such as brain imaging are often used to interpret whether a therapy is effective. Unfortunately, such stand-ins don’t always correlate with changes in cognition or quality of life.
A path forward
Lopera and other colleagues are now conducting a clinical trial in Colombia to test an antibody directed against a type of protein called amyloid, which collects in the brain plaques associated with Alzheimer’s disease.Regardless of the outcome of this trial, additional research and trials in Medellín and other parts of the world may help us better identify the underlying physiology of the disease, information the global scientific community desperately needs. Expanding the scope of our understanding can help expand the pipeline for drugs to target Alzheimer’s. There are likely many ways into this problem, but one thing is certain: The only way out of it is research.
And we must move more quickly. Given the low probability that any one clinical trial has for success, several colleagues and I recently estimated that if we continue today’s sequential way of doing clinical trials for Alzheimer’s disease, it will take 260 years before we get a treatment for it. Instead, let’s take multiple shots on goal by running several trials in parallel. Admittedly, this approach will require significant financial resources. But now is the time to collectively determine how to make these much-needed investments.
With the looming prospect of millions more affected by Alzheimer’s disease, an investment in the increasingly powerful scientific tools within the research community remains the best bet to achieve a cure.
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