A recent study published in the journal Neuropsychology suggests that having more physical tissue volume in six specific areas of the brain predicts better working memory in middle-aged and older adults. These findings provide evidence that preserving brain structure as we age supports our ability to temporarily hold and manipulate information. This knowledge could eventually guide new strategies to help slow cognitive decline in aging populations.
Working memory is the mental workspace that allows people to temporarily store and process information. People rely on this cognitive skill for everyday tasks like making decisions, learning new things, reading comprehension, and mental math. However, this mental capacity tends to decline as people reach their later years.
“Working memory is a fundamental cognitive function that we rely on every day, from following conversations, to planning tasks, and making decisions,” said study author Sarah Ellen Carnemolla, a postgraduate psychology student at Charles Sturt University.
In healthy aging, physical changes in the brain often happen before people notice any outward memory problems. Finding a link between the physical size of specific brain areas and memory performance might help experts identify who is most at risk for cognitive decline. This could also provide targets for therapies designed to protect the aging brain.
“We wanted to explore the topic of working memory in aging to deepen our understanding of the brain regions that support this crucial cognitive function, given that it naturally declines with age,” Carnemolla said. “Understanding the neurological basis of working memory is becoming more important with globally aging populations and increasingly common neurological and psychiatric conditions that affect working memory, such as ADHD and dementia.” By identifying the brain structures involved, the authors hope to contribute to future research aimed at improving quality of life for people experiencing memory impairments.
To measure working memory, experts often use a digit span task. In this traditional test, a person receives a sequence of numbers and must repeat them back. The backward version of this test requires the person to mentally reverse the order of the numbers. This demands extra mental effort and engages active manipulation skills.
Psychologists generally think of working memory as having a few separate parts. One part handles visual and spatial information, acting like a mental sketchpad. Another part handles verbal and auditory information, acting like a mental recording loop. An overarching executive system controls attention and coordinates these two storage areas to manage goal-directed behavior.
Past studies looking at the brain anatomy behind these skills have often relied on very small groups of people or individuals with severe brain injuries. Many previous projects also failed to account for outside factors that affect brain size, like a person’s age, biological sex, years of education, and overall head size. To address these gaps, authors wanted to test these relationships in a massive, healthy population using advanced brain scans.
To conduct the research, scientists analyzed data from the UK Biobank, which is a massive health database in the United Kingdom. The final sample included exactly 30,640 healthy adults between the ages of 51 and 80. Each participant completed a computerized memory assessment called the Numeric Memory Test.
During this visual test, a sequence of numbers appeared on a screen and then vanished after three seconds. Participants then had to type the numbers in reverse order using a digital keypad. The sequences became longer and more difficult as the test progressed, up to a maximum of 12 digits. The test ended when a person made too many consecutive mistakes.
Alongside the memory test, every participant underwent a magnetic resonance imaging (MRI) scan of their brain. This imaging technology uses strong magnets and radio waves to take detailed pictures of the body’s internal structures. The scientists used these images to measure the physical volume of 25 specific brain regions that previous literature linked to memory tasks.
Before running their statistical models, the scientists used specialized software to map out the different tissues in the brain. They separated the images into gray matter, white matter, and cerebrospinal fluid. This allowed them to isolate and measure the exact volume of the targeted areas with high precision.
The research team then used math to see if the sizes of these brain regions could predict how well someone performed on the memory test. They adjusted their equations to account for each person’s age, biological sex, years of education, and total intracranial volume. Intracranial volume simply refers to the total size of a person’s head and brain cavity.
The authors found that people with larger volumes in six specific brain areas tended to score higher on the memory test. One of these areas was the cerebellum, a region at the back of the brain traditionally known for coordinating movement. In this context, it likely helps people silently repeat the numbers to themselves, a strategy known as inner speech.
Another predictive region was the hippocampus, a seahorse-shaped structure deep in the brain. The hippocampus is famously linked to long-term memory formation, but this study suggests it also helps encode short-term visual information.
The other predictive areas included the superior temporal cortex and the insula, located on the sides of the brain. These regions typically help process sounds and manage attention. The insula in particular might help people switch their focus and ignore distractions while trying to remember the number sequence.
The left inferior parietal cortex and the left lateral occipital cortex also showed strong links to better test scores. These outer layers of the brain help people process visual and spatial information. Having more tissue in these regions likely assists in mentally picturing and rearranging the numbers like items on a mental chalkboard. “Our findings suggest that a network of brain regions plays an important role in supporting working memory throughout middle-age and older adulthood, and that the integrity of these brain structures matters for cognitive performance,” Carnemolla said.
However, the results also contained unexpected findings. When the statistical models accounted for all variables at once, three specific brain areas seemed to show a negative relationship with memory performance.
“Some brain regions showed associations with working memory performance that were in the opposite direction to what we expected (that is, for some regions, smaller size was associated with better performance),” Carnemolla told PsyPost. “We think this reflects the brain’s highly interconnected nature, where the influence of one region can be affected by its relationships with neighboring regions, making these patterns more complex than they first appear.”
Beyond brain anatomy, the study provides evidence that demographic factors heavily influence numeric memory. Older participants tended to remember fewer numbers than younger participants. At the same time, people with more years of formal education generally performed much better on the task than those with fewer years of schooling. “Our study also highlights the potential protective role of higher education in maintaining working memory as we age,” Carnemolla noted.
Interestingly, the researchers found no noticeable differences in performance between men and women. The overall size of a person’s head also did not predict how many numbers they could remember.
As a secondary goal, the researchers used this massive dataset to create benchmark scoring tables for the Numeric Memory Test. These tables group people by age, sex, and education level. Doctors can now use these charts to compare a new patient’s score against healthy peers, which makes it easier to spot abnormal memory problems.
The findings offer a detailed look at the aging brain, but the study does have some limitations. Because the data was collected at a single point in time, the researchers cannot prove that shrinking brain regions actually cause memory loss. It is only possible to say that brain volume and memory performance are related.
Additionally, the participant pool was not entirely representative of the general population. “Our study used data from the UK Biobank, whose participants tend to be more highly educated, of higher socioeconomic status, and predominantly of White ethnic backgrounds than the general population,” Carnemolla said. “This means the findings may not fully generalize to more diverse populations, highlighting the need for future research in broader and more representative groups.”
The visual format of the computerized test also allows people to simply read the numbers from right to left in their heads. This visual strategy might change how the brain tackles the problem compared to hearing numbers spoken aloud.
Future research should follow the same participants over many years to track how gradual brain shrinkage affects memory over time. The authors also suggest using a combination of different brain imaging techniques to build a more complete picture of how these regions communicate.
“As this was an Honors research project, my involvement with the study has now concluded,” Carnemolla said. “However, this work provides a foundation for future research into the brain networks that support working memory, including the potential for investigating how these findings might inform strategies to maintain or improve cognitive function across the lifespan.”
These future studies could help guide efforts to develop interventions that support or improve working memory. These strategies would take advantage of the brain’s natural capacity for change, a concept known as neuroplasticity. “Overall, the study reminds us that the health of our brain underpins many everyday abilities we often take for granted, and that understanding these relationships is an important step toward supporting cognitive health across the lifespan,” Carnemolla said.
To conclude, she offered gratitude to those who made the large-scale analysis possible. “We would like to sincerely thank the thousands of volunteers who generously contributed their time and data to the UK Biobank to advance our understanding of brain health and cognitive aging,” Carnemolla said.
The study, “Integrity in Six Key Brain Regions Predicts Numeric Working Memory Performance in 30,000 Middle-Aged and Older Adults: A UK Biobank Magnetic Resonance Imaging Study,” was authored by Sarah Ellen Carnemolla, Tanmoy Debnath, Md Geaur Rahman, and Minh Chau.
Leave a comment
You must be logged in to post a comment.