As Subdural Hematomas Increase, so do Brain Growth Studies

There will be 60,000 annual cases of chronic subdural hematoma (SDH) by 2030, making SDH the U.S.’s most common adult brain surgery disorder, says a new study by New York University (NYU) researchers.

To combat this, “it is critical to investigate mechanisms for decreasing brain atrophy in the elderly, as it renders them susceptible to chronic subdural hematoma,” Uzma Samadani, M.D., Ph.D., chief of neurosurgery at New York Harbor Health Care System, told Bioscience Technology. Samadani is lead author on the study.

Cesar Borlongan agreed. "This paper provides two key pieces of information," he told Bioscience Technology. Borlongan, a University of South Florida neurosurgeon, was uninvolved in the study. "First, it shows that veterans and the elderly are more prone to subdural hematomas than the general population. Second, it shows that a staggering number of subdural hematoma cases are projected to occur by 2030, [lending] credence to examination of veteran and age-related traumatic brain injuries.”

2030 is the year the last Baby Boomer turns 65.

The study’s “staggering” find

Subdural hematoma (subdural hemorrhage) is a condition where bleeding occurs on the brain’s surface, often caused by broken blood vessels. It is more common in the elderly due to their increased brain atrophy; their greater use of anti-coagulants (due to conditions like atrial fibrillation); and their weakened blood vessels. Even small head injuries can prompt bleeding on the surface of the brain in the elderly. As these bleeds accumulate, serious problems can arise.

SDHs are also more common in alcoholics—as alcohol is a blood thinner—and veterans.

Since U.S. incidence rates of SDH were unknown, the team of Samadani, who is also an assistant professor in the Departments of Neurosurgery, Psychiatry, Neuroscience and Physiology at NYU Langone Medical Center, set out to predict future chronic SDH incidence rates using U.S. Veterans Administration (VA) and civilian data sources.

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For the current work, published in the Journal of Neurosurgery, the team examined recent VA hospital visit data, and civilian incidence rates from Finland and Japan, where accurate records have led to a reliable mathematical model. The model took into consideration gender, age, and alcohol consumption, and was crafted to predict SDH incidence from 2012 to 2040.

VA hospital visit records from 2000 to 2012 showed 695 new SDHs, or 79.4 SDHs per 100,000 vets. Of those, 29 percent necessitated drainage surgery. More than 70 percent of SDHs occurred in patients 65 years and older.

Samadani’s team calculated that by 2030, when 25 percent of the U.S. population will be older than 65, there will be 121.4 chronic SDH cases per 100,000 vets, and 17.6 cases per 100,000 US civilians.

This will impact hospitals in another way, as SDH surgical patients have significantly longer hospital stays than even brain tumor patients, as noted in an assessment of patients treated for SDHs at the New York Harbor VA from 2008 to 2010. SDH patients also often require more intense rehabilitation.

Combatting brain atrophy

Samadani told Bioscience Technology she was most surprised, in the course of the study, by the greater incidence of SDH among vets. Regardless, the massive total SDH numbers means it will be critical to do something, first and foremost, about brain atrophy, she said. (As we grow older, our brains shrink away from the sides of our skulls, leaving an inviting vacuum for blood to fill: brain atrophy.)

Samadani is examining vagus nerve stimulation, toward that end. The FDA has approved her clinical trial for this. But there are many approaches being studied.

Many heart conditions call, for example, for elderly people to take anti-coagulants like warfarin, which can facilitate bleeding accidents. There are newer anti-coagulants (NOACs), which are billed as prompting less bleeding. Still, at this point, “the NOACs are still too new to have sufficient data for us to understand bleeding incidence,” Samadani told Bioscience Technology.

Indeed, a study published in a recent Vascular Medicine points at controversy over the use of NOACs for atrial fibrillation.

Massachusetts General Hospital Clinical Research Program Director Maurizio Fava is heading a Phase 1 trial seeking to discover whether a small molecule, isolated by screening with stem cells generated by the company Neuralstem, can increase neurogenesis in depressed patients’ brains. Earlier in vitro work established the same molecule prompts rat hippocampi to significantly enlarge.

But there are more home-spun remedies. As noted in a March 2015 Cell Transplantation paper from a group led by Borlongan, many studies have established exercise significantly boosts neurogenesis (brain neuron birth) in humans.

Borlongan’s group has devised an animal model to identify growth and trophic factors our bodies excrete during exercise to boost brain growth—in the hope some of those chemicals, isolated, expanded, and reinjected, may boost brain growth on their own, sans exercise, in patients who cannot move much.

And this month, a Johns Hopkins group reports in Alzheimer’s and Dementia that simple “civic engagement” for two years may not only have prompted hippocampal brain growth in older men, but improved their memories.

For this small study, Michelle Carlson and team randomized 111 men and women to either participate in the Experience Corps (58) or not (53). MRIs were taken at enrollment, and after 12 and 24 months. Memory tests were given. Participants were healthy, an average of 67.2 years old, largely African-American, and were not well off, although they had some college education.

The participants not involved in Experience Corps displayed age-related shrinkage in brain volumes. As a rule, yearly atrophy rates for people over age 65 range from .8 percent to two percent. But the men in Experience Corps exhibited a .7 percent to 1.6 percent increase in brain volumes over two years.

Women did not show the same gains.

The team is not yet sure what aspects of the Experience Corps program may have led to the improved memory function and increased brain volumes. But the program included involvement in many different kinds of activities that retired people often do not adopt otherwise. They walked to buses, and up and down stairs in schools. They worked with young people and in teams. They shared their knowledge, and they did some good works, including educating children. They worked through problem solving exercises, and socialized in ways they normally wouldn’t, at home.

Combination of approaches

That study was small. But proof that exercise can repair the brain grows daily. “The concept that exercise enhances neurogenesis was popularized by Rusty Gage and colleagues,” Borlongan noted to Bioscience Technology. “In this and other papers, this group and others showed that new cells almost doubled in the hippocampus after just 12 days of daily running. Over the next decade, exercise has been demonstrated to reverse some of the symptoms of age-related disorders, such as Alzheimer’s, Parkinson’s, stroke, and traumatic brain injury.”

But a combination of approaches may ultimately be the final answer, Borlongan concluded.

"We evaluated growth factors reduced following lack of exercise," he said. These growth factors, as noted, can be administered to inactivated patients. "But while small molecules may promote neurogenesis, these molecules may not fully substitute for the therapeutic benefits of exercise. Physical or rehabilitation therapy, combined with small molecules, may prove more effective for patients who may be unable to perform independent exercise."