Posted on Older people's health

Why do we move slower the older we get? New study delivers answers

Costs of reaching

Mary Kaupas participates in an experiment to study how humans of various ages reach for targets. Tubes monitor her breathing to measure how much energy she uses. CREDIT Erik Summerside/Mary Kaupas

It’s one of the inescapable realities of ageing: The older we get, the slower we move—whether walking around the block or just reaching for the remote control.

A new study led by University of Colorado Boulder engineers helps explain why.

The research is one of the first studies to experimentally tease apart the competing reasons why people over age 65 might not be as quick on their feet as they used to be. The group reported that older adults might move slower, at least partly, because it costs them more energy than younger people—perhaps not too shocking for anyone who’s woken up tired the morning after an active day.

The findings could one day give doctors new tools for diagnosing a range of illnesses, including Parkinson’s disease, multiple sclerosis and even depression and schizophrenia, said study co-author Alaa Ahmed. 

“Why we move the way we do, from eye movements to reaching, walking and talking, is a window into ageing and Parkinson’s,” said Ahmed, professor in the Paul M. Rady Department of Mechanical Engineering. “We’re trying to understand the neural basis of that.”

For the study, the group asked subjects aged 18 to 35 and 66 to 87 to complete a simple task: to reach a target on a screen, like playing a video game on a Nintendo Wii. By analyzing patterns of these reaches, the researchers discovered that older adults seemed to modify their motions under certain circumstances to conserve their limited energy supplies. 

“All of us, whether young or old, are inherently driven to get the most reward out of our environment while minimizing the amount of effort to do so,” said Erik Summerside, a co-lead author of the new study who earned his doctorate in mechanical engineering from CU Boulder in 2018.

Using engineering to understand the brain

Ahmed added that researchers have long known that older adults tend to be slower because their movements are less stable and accurate. But other factors could also play a role in this fundamental part of growing up.

According to one hypothesis, the muscles in older adults may work less efficiently, meaning that they burn more calories while completing the same tasks as younger adults—like running a marathon or getting up to grab a soda from the refrigerator.

Alternatively, ageing might also alter the reward circuitry in the human brain. Ahmed explained that as people age, their bodies produce less dopamine, a brain chemical that gives them a sense of satisfaction after a job well done. If you don’t feel that reward as strongly, the thinking goes, you may be less likely to move to get it. People with Parkinson’s disease experience an even sharper decline in dopamine production.

In the study, the researchers asked more than 80 people to sit down and grab the handle of a robotic arm, which, in turn, operated the cursor on a computer screen. The subjects reached forward, moving the cursor toward a target. If they succeeded, they received a reward—not a big one, but enough to make their brains happy.

“Sometimes, the targets exploded, and they would get point rewards,” Ahmed said. “It would also make a ‘bing bing’ sound.”

Moving slower but smarter

That’s when a contrast between the two groups of people began to emerge.

Both the 18 to 35-year-olds and 66 to 87-year-olds arrived at their targets sooner when they knew they would hear that bing bing—roughly 4% to 5% sooner over trials without the reward. But they also achieved that goal in different ways.

The younger adults, by and large, moved their arms faster toward the reward. The older adults, in contrast, mainly improved their reaction times, beginning their reaches about 17 milliseconds sooner on average.

When the team added an 8-pound weight to the robotic arm for the younger subjects, those differences vanished.

“The brain seems to be able to detect very small changes in how much energy the body is using and adjusts our movements accordingly,” said Robert Courter, a co-lead author of the study who earned his doctorate in mechanical engineering from CU Boulder in 2023. “Even when moving with just a few extra pounds, reacting quicker became the energetically cheaper option to get to the reward, so the young adults imitated the older adults and did just that.”

The research seems to paint a clear picture, Ahmed said: Both the younger and older adults didn’t seem to have trouble perceiving rewards, even small ones. But their brains slowed down their movements under tiring circumstances.

“Putting it all together, our results suggest that the effort costs of reaching seem to be determining what’s slowing the movement of older adults,” Ahmed said.

The experiment can’t completely rule out the brain’s reward centers as a culprit behind why we slow down when we age. But, Ahmed noted, if scientists can tease out where and how these changes emerge from the body, they may be able to develop treatments to reduce the toll of aging and disease.

Posted on Multiple Sclerosis

PET scans reveal ‘smouldering’ inflammation in patients with multiple sclerosis

The new technique could lead to more advanced treatments for multiple sclerosis
The new technique could lead to more advanced treatments for multiple sclerosis.

A new study from Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, suggests that positron emission tomography (PET) brain scans could reveal hidden inflammation in patients with multiple sclerosis (MS) who are being treated with highly effective treatments. The findings were published in Clinical Nuclear Medicine.

“One of the perplexing challenges for clinicians treating patients with MS is after a certain amount of time, patients continue to get worse while their MRIs don’t change,” said lead author Tarun Singhal, MD, MBBS, an associate professor of Neurology in the Brigham’s Department of Neurology and director of the PET Imaging Program in the Ann Romney Center for Neurologic Diseases.  “This is a new approach that is potentially going to be very helpful for the field, for research, and hopefully for clinical use.”

Singhal collaborated with others in the Brigham Multiple Sclerosis Center and the Ann Romney Center. The study started when Singhal noticed that patients treated with the most effective MS treatments were experiencing worsening symptoms. The team has worked for the past eight years on developing an approach of imaging cells called microglia. Microglia are immune cells in the brain that are thought to have a role in MS disease progression but cannot be seen by a routine MRI. The team developed a technique called F18 PBR 06 PET imaging. It involves the injection of a tracer, or dye, that binds to the microglia cells.

Rohit Bakshi, MD, of the Department of Neurology and a co-author on the paper, said increased microglial activity means more atrophy of grey matter in the brain.

“This can affect cognition, movement, fine motor skills, and other aspects of their life,” Bakshi said.

In their paper, the authors describe the term “smouldering” inflammation. Just as a smouldering fire can burn slowly without smoke or flame, smouldering inflammation may linger in patients with MS, driving disease progression and symptoms, even when it cannot be assessed on MRI.

The newly published study involved performing PET scans on 22 people with MS and eight healthy controls. Researchers measured the glial activity load on the PET scans, a new measure developed in Singhal’s lab where lab members looked at the level of smouldering inflammation from microglia in MS patients. They compared those scans to patients’ disability and fatigue levels and not only found that PET scans could show hidden inflammation caused by microglia, but the damage to patients’ brains correlated with the disability and fatigue levels they were experiencing. The researchers were also able to better classify patients with MS between high-efficacy and low-efficacy treatments. Those with low-efficacy treatments had more abnormalities on their PET scans, suggesting more microglial cell activation. Those using high-efficacy treatments had a lower degree of PET abnormality than those on no or low-efficacy treatments but still had an abnormal increase of microglial activation compared to healthy people, suggesting that while high-efficacy treatments helped to reduce neuroinflammation, there was residual inflammation despite treatment, which could account for future worsening and progression independent of relapse activity (PIRA) in these MS patients.

“Our therapies are excellent in that we’ve improved MS patients’ lives,” Bakshi said. “There’s no doubt about that, but we’re still not at the finish line.”

One limitation to the study is the initial group was small. The authors note that PET scans can also be expensive and expose patients to some level of radiation, whereas MRIs do not. Singhal said that radiation could be reduced because of the long half-life and the requirement for a lower administered dose of the F18 PBR06 tracer. The tracer also produces better imaging characteristics than previously used tracers with shorter half-lives.

Bakshi said despite the limitations, the study shines an important light on the power of PET scanning, specifically to find microglial activation.

“This study tells us something new about the disease and may be giving us an important clue as to what is driving disease progression in patients,” he said.

Singhal said before the technique can be used routinely in a clinical setting, it must be validated on a larger sample size. Other longer half-life PET tracers have been approved by the FDA for clinical use, for example, amyloid PET tracers for studying Alzheimer’s disease. If approved, [F-18]PBR06 could also be used to personalize and predict a patient’s treatment course in MS and other brain diseases. However, the authors note that even before approval, [F-18]PBR06 can help advance drug development and perform multicentric clinical trials.

“It’s very exciting that our novel approach worked and correlated so strongly with clinical measures we assessed,” he said. “It means our approach is relevant clinically.”

Posted on Pain Management

Chronic pain linked to socioeconomic background – new study

Development of chronic musculoskeletal pain can be influenced by socioeconomics, fear of movement, smoking and poorer support networks, new research shows. 

In a systematic review of current evidence, researchers found that people from a lower socioeconomic background were twice as likely to develop chronic pain following injury.  

Those with a combination of characteristics, including smoking, high level of pain at the time of injury, fear of movement, poorer support networks and a lower level of education or household income, maybe seven times more likely to develop chronic pain after an injury. The results are published in PLOS One. 

Pain is described as ‘acute’ when it has been present for a short period of time – anything that lasts for less than three months after initial injury. Pain is described as chronic when it has been present for longer than three months after initial injury. Chronic musculoskeletal pain affects about 43 per cent of the UK population and is the greatest cause of disability worldwide, often persisting for many years or indefinitely. People with chronic pain often experience poorer quality of life and are also more likely to develop diseases including cancer, cardiovascular diseases and diabetes.  

Current approaches to managing chronic pain focus on physical rehabilitation at the site of the pain, or injury. However, the body’s healing process usually takes place over no longer than three months, suggesting that the reasons for longer-term pain are more complex. 

Lead author Michael Dunn, of the University of Birmingham and St. George’s University Hospitals NHS Foundation Trust, said: “The purpose of acute pain is to alter behaviour to protect the body from harm, but chronic pain persists because of a sensitised nervous system that continues our experience of pain, even after the healing process has completed.”  

This process, the researchers found, is influenced by a range of psychological and social factors and so treatment which focuses solely on the injured body part is often ineffective. 

Mr Dunn continued: “The characteristics that we have identified are related particularly to an individual’s experiences, rather than a type of injury. For that reason, approaches to treating people with musculoskeletal injuries should be more person-centred, focusing on broader biological, psychosocial and social well-being. Put simply, current healthcare approaches do not address all the reasons people do not get better.” 

The researchers also identified other factors related to developing chronic pain, such as lower job satisfaction, stress and depression. These characteristics were supported by lower quality evidence, but are also linked to lower socioeconomic backgrounds. 

“People from lower socioeconomic backgrounds are twice as likely to develop chronic pain after injury. This indicates that not only are current healthcare approaches inadequate, they may also be discriminatory, with current healthcare approaches that are orientated around the injured body part being geared towards those from higher socioeconomic backgrounds who are less likely to experience these psychological or social factors,” said Mr Dunn.