The human brain declines later than previously thought, major study finds
[Mar. 22, 2023: JJ Shavit, The Brighter Side of News]
The team discovered that the connections in our brain become increasingly faster as we age, from two to four meters per second. (CREDIT: Creative Commons)
Recent research conducted by Clinical Technologist Dorien van Blooijs, Neurologist Frans Leijten, and their colleagues from University Medical Center Utrecht (UMC Utrecht) and Mayo Clinic, has found that our brains decline later than previously thought. This decline occurs between the ages of 30 and 40, rather than after our 25th year of life. The results of the research were published in Nature Neuroscience, providing significant insight into how our brain develops and functions over time.
The research focused on the processing speed of our brain and how it changes as we age. The team discovered that the connections in our brain become increasingly faster as we age, from two meters per second in children aged four to four meters per second in people aged between thirty and forty.
The increase represents a doubling of the speed of connections. Only after the age of 40, the speed of connections slows down. "Our brain continues to develop a lot longer than we thought," Van Blooijs said.
The researchers also discovered that there were differences in the development of different brain regions. The frontal lobe, responsible for thinking and performing tasks, develops longer than the area responsible for movement. This observation had already been made in previous research but had now been supported with concrete data. The development of speed is not a straight line but rather a curve.
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The team obtained the data through precise measurements using an electrode grid that is implanted on the brains of epilepsy patients before surgery. The grid consists of 60-100 electrodes that measure brain activity. By stimulating the electrodes with short currents, the researchers could see which brain areas responded abnormally. This allowed them to create a map of which areas should and should not be removed during epilepsy surgery, providing a new insight into the study of the human brain.
"We have been collecting this data for about 20 years," Leijten said. "It wasn't until a few years ago that we realized we could use the unaffected areas as a model for the healthy human brain." Van Blooijs added: "If you stimulate an electrode in one area, a reaction occurs in another. That lets you know the two areas are connected. You can then measure how long it takes for the reaction to occur. If you know the distance between the two different brain regions, you can calculate how fast the signal is transmitted."
The results of the study provide important information about our central nervous system, and scientists have long been trying to map the connections in our brain. With this information, experts can make more realistic computer models of our brain. For these models to work, in addition to information about the connections, precise values concerning the speed of those connections are needed.
Electrode positions, fiber tracts and evoked potentials. MNI brain surface showing white matter tracts and electrode positions at endpoints from all 74 subjects. (CREDIT: Nature Neuroscience)
"We now have these numbers for the very first time," Leijten explains, "With our data, researchers can make new and better computer models that increase our understanding of the brain. We expect our work to not only advance epilepsy research but also research into other brain disorders."
Another area where the results of this study could be applicable is in the development of treatments for brain disorders. With a better understanding of how the brain works and changes as we age, researchers can develop more effective treatments for diseases that affect the brain, such as Alzheimer's, Parkinson's, and multiple sclerosis.
Developmental trajectory of conduction delay and speed across long-range connections. Average transmission latency and speed estimated by the N1 component for the AF, frontal-parietal SLF, frontal-central SLF and TPAT (left to right). Gray bars show distributions within each subject, the bar width scales with the number of measured responses. (CREDIT: Nature Neuroscience)
The research conducted by the team from UMC Utrecht and the Mayo Clinic is just one example of the many studies being done around the world to advance our understanding of the brain. As our understanding of the brain continues to grow, so too does our ability to treat and cure brain disorders.
Other recent studies that address the age when the human brain begins to decline
In a study published in the journal Neurobiology of Aging in 2020, researchers from the University of Cambridge found that some brain functions, such as memory and cognitive processing speed, begin to decline as early as age 45. The study involved over 500,000 participants aged 16 to 90, and the researchers used data from an online cognitive testing platform to assess different aspects of cognitive function.
A study published in the journal Nature Communications in 2019 found that the brain's white matter, which is responsible for transmitting signals between different parts of the brain, begins to decline in early adulthood, around age 30. The researchers used magnetic resonance imaging (MRI) to measure the integrity of the brain's white matter in over 3,000 participants aged 44 to 77.
Another study published in the journal Frontiers in Aging Neuroscience in 2017 found that certain areas of the brain, such as the prefrontal cortex, which is responsible for decision-making and planning, begin to decline in function as early as age 30. The study involved over 800 participants aged 18 to 74, and the researchers used a range of cognitive tests to assess different aspects of brain function.
The research conducted by the UMC Utrecht and Mayo Clinic team marks an important milestone in our understanding of how our brains develop and function over time. By providing precise measurements of the speed of connections in our brain, the team has given scientists and medical experts an opportunity to better understand the workings of the human brain.
The findings will help pave the way for future research into brain disorders and provide an opportunity to develop new and more effective treatments for epilepsy and other neurological disorders.
For more science and technology stories check out our New Discoveries section at The Brighter Side of News.
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