Neuroimaging Key to Early Detection of Alzheimer’s
Alzheimer disease is on the rise, but researchers hope recent advances in early detection will shift those numbers into reverse.
“By the time a person begins showing symptoms of Alzheimer disease, irreversible damage has already occurred in the brain. But if we can detect the disease early before symptoms arise, we can intervene to stop the damage,” said Gustavo Román, M.D., director of the Nantz National Alzheimer Center at Houston Methodist Hospital.
Román is directing the center’s 3rd Annual International Alzheimer Symposium which takes place Oct. 16, from 8 a.m. to 4:30 p.m. at the Houston Methodist Research Institute, 6670 Bertner. The one-day seminar hosts leading scholars from the United States and Europe who will share their collective knowledge about the rapid advancements being made in neuroimaging of Alzheimer disease and other forms of dementia in aging.
Neuroimaging involves using imaging technology, such as MRI or PET scans, to take a 3-dimensional picture of the brain and pinpoint abnormalities.
These images can detect not only the brain atrophy that occurs in Alzheimer disease, but also the presence of plaques – deposits of apparently toxic protein fragments called beta-amyloid – that build up between the brain’s nerve cells.
“Though most people develop some plaques as they age, those with Alzheimer’s tend to develop far more,” Román said. “They also tend to develop plaques in a predictable pattern, beginning in areas important for memory before spreading to other regions.”
Most scientists believe the plaques somehow block communication among nerve cells and disrupt processes that cells need to survive.
“It’s the destruction and death of nerve cells that causes memory failure, personality changes, problems carrying out daily activities and other symptoms of Alzheimer disease,” Román said.
Joseph Masdeu, M.D., Ph.D., a scientist with the National Institutes of Health’s neuroimaging section and a presenter at the conference, said scientists first used a form of neuroimaging called positron emission tomography, or PET scans, to detect plaque 10 years ago.
These PET scans revealed that plaque slowly accumulates in the brain as many as 10 to 25 years before Alzheimer’s symptoms appear.
“By the time the patient notices something is wrong and visits the doctor, as much as 40 percent of nerve cells in some parts of the brain may have already disappeared,” said Masdeu. “Some damage has already been done, and it’s irreversible with current medications.”
But some people have memory loss caused by diseases other than Alzheimer’s that are treatable, which is why patients should see their physicians at the first hint of a problem.
Masdeu said dementia is preceded by a condition known as mild cognitive impairment.
“Even before mild cognitive impairment happens, it is possible that by removing amyloid from the brain, for instance by means of antibodies, we may be able to prevent people with excessive brain amyloid from developing Alzheimer disease,” he said.
To determine whether this approach works, three clinical trials were launched earlier this year and are currently underway. Amyloid can also be measured in cerebrospinal fluid, Masdeu said.
Does this mean all adults will undergo routine scans and spinal taps?
“No,” said Masdeu. “But once a therapy becomes available, it would make sense to scan first-degree relatives of Alzheimer disease patients – those whose parents or siblings were diagnosed with the disease.”
People at genetic risk for a rare, early-onset form of Alzheimer’s that represents less than 1 percent of all Alzheimer’s cases should also be scanned early in life, he said.
“By the time the patient notices
—Joseph Masdeu, M.D., Ph.D.
“This group of people with this very rare genetic mutation is very valuable to researchers,” Masdeu said. “Because this population gets Alzheimer’s so early, usually in their 40s or 50s, they can provide us with an accelerated look at how the disease can progress as the amyloid plaque starts forming in their brains in their late 20s and early 30s. The lessons we learn from these individuals may be applicable to others with the much more common, garden-variety form of Alzheimer’s.”
A game-changer came last year with the Food and Drug Administration’s approval of Amyvid, a new amyloid imaging agent that is used clinically to estimate brain amyloid plaque content in patients with cognitive decline.
Imaging to detect amyloid plaques in the brain is at a crossroads, Masdeu said, because insurance companies, and Medicare, are still deciding if they will pay for this costly procedure. To have access to drugs that are being tested for amyloid removal, individuals must be enrolled in clinical trials.
Houston Methodist will start a treatment trial for the non-early onset, garden variety form of Alzheimer’s soon, Román said, though the trial is still in the planning stages.
In the meantime, lifestyle changes can slow or prevent the growth of plaque, he said. Conversely, buildup can be accelerated by high blood pressure, diabetes, clogged arteries, concussions and inflammation.
Román says what’s good for the heart is good for the brain, and suggests patients follow the heart-healthy Mediterranean diet, which emphasizes plant-based foods, seafood and poultry, olive oil, and red wine in moderation.
An April study in JAMA Neurology found that those who follow the Mediterranean diet experience less blood vessel damage in the brain than those who consume red meats, saturated fats and refined grains.
Exercise, too, promotes brain cell growth, Román said, especially in the hippocampus, an area of the brain that plays an important role in memory. Getting adequate sleep, staying social, and learning new things can also lower the risk for Alzheimer’s, he said.
According to the Alzheimer’s Association 2013 Disease Facts and Figures report, more than 5 million Americans have Alzheimer’s today, with a new case being diagnosed every 68 seconds. Since 2000, deaths from Alzheimer’s have risen 68 percent, while deaths from other major diseases, like heart disease and stroke, breast and prostate cancers, and HIV, have decreased.
Román hopes early detection through neuroimaging will reverse Alzheimer’s upward spiral.
“We have tools today to help us understand what’s happening, and with understanding, we can do something about it,” he said. “For the first time, we have hope.”
For more information on the 3rd Annual International Alzheimer Symposium, visit HoustonMethodist.com/AlzheimerSymposium. The symposium is free but limited to 200 attendees.