Brain aging is inevitable to some extent, but it is not uniform; it affects everyone, or every brain, differently.
Slowing down brain aging or stopping it altogether would be the ultimate elixir to achieve eternal youth. Is brain aging a slippery slope that we need to accept? Or are there steps that we can take to reduce the rate of decline?
At around 3 pounds in weight, the human brain is a staggering feat of engineering, with around 100 billion neurons interconnected via trillions of synapses.
Throughout a lifetime, the brain changes more than any other part of the body. From the moment the brain begins to develop in the third week of gestation to old age, its complex structures and functions are changing, networks and pathways connecting and severing.
During the first few years of life, the brain forms more than 1 million new neural connections every second. The size of the brain increases fourfold in the preschool period, and by age 6, it reaches around 90% of its adult volume.
The frontal lobes are the area of the brain responsible for executive functions, such as planning, working memory, and impulse control. These are among the last areas of the brain to mature, and they may not develop fully until around 35 years of age.
As people age, their bodily systems — including the brain — gradually decline. “Slips of the mind” are associated with getting older. That said, people often experience those same slight memory lapses in their 20s but do not give it a second thought.
Older adults often become anxious about memory slips due to the link between impaired memory and Alzheimer’s disease. However, Alzheimer’s and other dementias are not a part of the normal aging process.
Common memory changes that are associated with normal aging include:
- Difficulty learning something new: Committing new information to memory can take longer.
- Multitasking: Slowed processing can make planning parallel tasks more difficult.
- Recalling names and numbers: Strategic memory, which helps with remembering names and numbers, begins to decline at age 20.
- Remembering appointments: Without cues to recall the information, the brain may put appointments into “storage” and not access them unless something jogs the person’s memory.
Although some studies show that one-third of older adults struggle with declarative memory — that is, memories of facts or events that the brain has stored and can retrieve — other studies indicate that one-fifth of 70-year-olds perform cognitive tests just as well as people aged 20.
Scientists are currently piecing together sections of the giant puzzle of brain research to determine how the brain subtly alters over time to cause these changes.
General changes that researchers think occur during brain aging include:
- Brain mass: Shrinkage in the frontal lobe and hippocampus, which are areas involved in higher cognitive function and encoding new memories, starts at around the age of 60 or 70 years.
- Cortical density: This refers to the thinning of the outer-ridged surface of the brain due to declining synaptic connections. Fewer connections may contribute to slower cognitive processing.
- White matter: White matter consists of myelinated nerve fibers that are bundled into tracts and carry nerve signals between brain cells. Researchers think that myelin shrinks with age, and, as a result, processing is slower and cognitive function is reduced.
- Neurotransmitter systems: Researchers suggest that the brain generates fewer chemical messengers with age, and it is this decrease in dopamine, acetylcholine, serotonin, and norepinephrine activity that may play a role in declining cognition and memory and increasing depression.
In understanding the neural basis of cognitive decline, researchers can uncover which therapies or strategies may help slow or prevent brain deterioration.
Several brain studies are ongoing to solve the brain aging conundrum, and scientists are frequently making discoveries.
The sections below will outline some of these in more detail.
In 2017, researchers from Albert Einstein College of Medicine in New York City, NY, revealed in a mouse study that stem cells in the brain’s hypothalamus likely control how fast aging occurs in the body.
“Our research shows that the number of hypothalamic neural stem cells naturally declines over the life of the animal, and this decline accelerates aging,” says Dr. Dongsheng Cai, a professor of molecular pharmacology.
“But,” he adds, “we also found that the effects of this loss are not irreversible. By replenishing these stem cells or the molecules they produce, it’s possible to slow and even reverse various aspects of aging throughout the body.”
Injecting hypothalamic stem cells into the brains of normal old and middle-aged mice, whose stem cells had been destroyed, slowed or reversed measures of aging. The researchers say that this is a first step toward slowing the aging process and potentially treated age-related conditions.
“SuperAgers” are a rare group of individuals over the age of 80 years who have memories as sharp as those of healthy people decades younger.
Research by scientists at Northwestern University Feinberg School of Medicine in Chicago, IL, compared SuperAgers with a control group of same-age individuals.
They found that the brains of the SuperAgers shrink at a slower rate than those of their age-matched peers, which results in a greater resistance to the typical memory loss that occurs age. This suggests that age-related cognitive decline is not inevitable.
“We found that SuperAgers are resistant to the normal rate of decline that we see in average [older adults], and they’re managing to strike a balance between life span and health span, really living well and enjoying their later years of life,” says Emily Rogalski, an associate professor.
By studying how SuperAgers are unique, the researchers hope to unearth biological factors that might contribute to maintaining memory ability in advanced age.
Researchers have discovered several factors that speed up brain aging.
A growing body of evidence suggests that people who experience the least declines in cognition and memory all share certain habits:
- engaging in regular physical activity
- pursuing intellectually stimulating activities
- staying socially active
- managing stress
- eating a healthful diet
- sleeping well
Recent research highlights a plethora of ways that people can actively take charge of their health and perhaps decrease the rate at which their brains age.
The following sections will look at some of these tips in more detail.
One intervention that crops up time and time again to stave off age-related mental decline is physical exercise.
Performing a combination of aerobic and resistance exercise of moderate intensity for at least 45 minutes each session on as many days of the week as possible can significantly boost brain power in people aged 50 and over.
Likewise, other research by the University of Miami in Florida found that individuals over the age of 50 who engaged in little to no exercise experienced a decline in memory and thinking skills comparable to 10 years of aging in 5 years, compared with those who took part in moderate or high intensity exercise.
Essentially, physical activity slowed brain aging by 10 years.
Dancing may also have an anti-aging effect on the brains of older adults. A study by the German Center for Neurodegenerative Diseases in Magdeburg found that although regular exercise can reverse the signs of brain aging, the most profound effect was among people who danced.
Playing an instrument
Researchers at Baycrest Health Sciences in Toronto, Canada, revealed why playing a musical instrument may help older adults ward off age-related cognitive decline and retain their listening skills.
Researchers found that learning to play a sound on a musical instrument changes brain waves in such a way that improves an individual’s listening and hearing skills. The alteration in brain activity indicates that the brain rewires itself to compensate for disease or injuries that might prevent a person’s ability to perform tasks.
“It has been hypothesized,” says Dr. Bernhard Ross, a senior scientist at Baycrest’s Rotman Research Institute, “that the act of playing music requires many brain systems to work together, such as the hearing, motor, and perception systems.”
“This study was the first time we saw direct changes in the brain after one session, demonstrating that the action of creating music leads to a strong change in brain activity,” he adds.
Eating a healthful diet
Another study has also determined that consuming foods included in the Mediterranean or MIND diet is associated with a lower risk of memory difficulties in older adults.
Research by the University of Illinois at Urbana-Champaign discovered that middle-aged people with higher levels of lutein — which is a nutrient present in green leafy vegetables, such as kale and spinach, as well as eggs and avocados — had similar neural responses to younger individuals than those of people of the same age.
“As people get older, they experience typical decline. However, research has shown that this process can start earlier than expected. You can even start to see some differences in the 30s,” says first study author Anne Walk, a postdoctoral scholar.
“We want to understand how diet impacts cognition throughout the life span,” she adds. “If lutein can protect against decline, we should encourage people to consume lutein-rich foods at a point in their lives when it has maximum benefit.”
The number of adults in the United States over the age of 65 is set to more than double in the next 40 years, rising from 40.2 million in 2010 to 88.5 million by 2050.
Due to this aging population, it will become increasingly important to understand the cognitive changes that go hand in hand with aging.
Although many questions remain regarding the aging brain, research is making progress in illuminating what happens to our cognitive functions and memory throughout our lifetime.
It is also emphasizing the ways in which we can preserve our mental abilities to improve our quality of life as we advance into older adulthood.