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Aging

Brain Shrinking After 30: Myth or Reality?

Our brains shrink as we age, but it's not always a cause of cognitive decline.

Key points

  • After age 30, our brains start to lose volume.
  • Maintaining a healthy lifestyle is key to preventing age-related cognitive decline.
  • The fact that your brain shrinks after 30 is not entirely a myth nor a cause for alarm.

Mark Twain said, “Age is an issue of mind over matter. If you don’t mind, it doesn’t matter.”

When it comes to brain health, minding does matter. It may seem hard to believe, but after age 30, our brains begin to lose volume. Some brain functions, such as memory, the ability to process information, and spatial awareness, may decline as we age. However, it is possible for verbal skills and abstract reasoning to improve. Scientists are learning more about what happens to our brain as we age, and the good news is there are things you can do to prevent its inevitable decline.

The Science Behind Brain Aging

As infants and young children, our brains develop more than a million new connections every second. I can almost see this happening when I interact with my young grandson. It is almost as if the wheels in his head are constantly turning. When children reach the age of 6, coincident with starting first grade, their brains have already reached 90% of their eventual adult volume. Starting in our 30s, our brain's volume and weight gradually decline. This is most significant in the prefrontal cortex and hippocampus. These areas are responsible for memory, decision-making, and executive control.

Neurochemical changes are also age-related. Neurotransmitters like serotonin, dopamine, and norepinephrine decline in quantity as we age. Research shows that older adult brains manufacture less dopamine, and one study that looked at the brains of 60- and 70-year-old subjects reported that they had less measurable serotonin.

Some individuals develop an accumulation of proteins believed to contribute to neurodegenerative diseases. In patients with Alzheimer’s disease, abnormal levels of tau protein create tangles and lead to a decline in cognitive function.

Contributing Factors

Various factors can influence the rate and extent of brain shrinkage. These include genetics, lifestyle choices, and overall health.

  • Genetics. Genetic factors may predispose some individuals to neurodegenerative diseases such as Alzheimer's disease or other forms of dementia.
  • Lifestyle. What’s good for your heart is good for your brain. Exercise boosts blood flow to your brain and encourages new nerve growth. The Chicago Health and Aging Project is a study that was conducted in four Chicago communities over 19 years. Blood levels of tau protein were obtained from each of the 1100 participants who self-reported their amount of physical exercise. Over time, the researchers found that exercise made a difference in the extent of their cognitive decline, even among those with high tau levels. The most effective method was two-and-a-half hours or more of physical exertion per week. This correlated with a 58% slower rate of cognitive decline than those with little to no activity at all.
  • Diet. The American Heart Association recommends the Mediterranean diet, which is also helpful for brain health. It emphasizes plant-based foods and healthy fats. It is not a diet per se but rather a lifestyle that minimizes processed foods, high unsaturated fats, and lower amounts of red meat. It is full of fruits, vegetables, and healthy grains.
  • Alcohol. Heavy alcohol consumption contributes to heart disease, some forms of cancer, and accelerated brain shrinkage. Heavy consumption is three or more drinks for women and four or more for men per day.
  • Mental activity. A study by the Rush Memory and Aging Project reported that older participants who engaged in cognitive activities such as reading, playing games like chess, or spending time with friends or relatives developed dementia up to five years later than those who did not.
  • Give up smoking. Smoking also contributes to heart disease, cancer, and brain aging. According to researchers at Washington University in St. Louis School of Medicine, smoking contributes to decreased brain volume, which is irreversible.
  • Sleep. During sleep, a system called the glymphatic system flushes out waste products that accumulate in your brain during wakefulness. This is particularly important because it helps to prevent the buildup of toxic proteins that can lead to dementia.

A study funded by the National Institute on Aging studied almost 3,000 adults and found that people who practiced four or more of these behaviors had a 60% lower risk of developing Alzheimer’s than those who followed none or only one.

Cognitive Reserve

Some degree of brain shrinkage is a natural part of aging. However, it doesn't necessarily lead to significant cognitive impairment. Many people maintain sharp cognitive function well into their later years because their brains possess a remarkable capacity for adaptation and compensation. This is known as cognitive reserve and it helps account for the sometimes remarkable recovery that adults can make after a brain injury or illness.

Cognitive reserve refers to the brain's ability to improvise and find alternate ways of completing tasks. Individuals with a higher cognitive reserve can better cope with age-related changes and are less likely to experience noticeable cognitive decline. This reserve is built over a lifetime of intellectual activities, education, and rich social interactions.

Cognitive Super-Agers

According to experts at the Northwestern School of Medicine, cognitive super-agers are people 80 years or older with cognitive functions comparable to someone in middle age. On brain scans, these people show less brain shrinkage than would be expected at their stage of life and, because of this, may be more protected against developing dementia. The scientists who studied this group noted that they share some common habits, including many of those listed above. The researchers concluded that:

  • Staying physically active is one of the best things you can do for your health. In addition to increasing oxygen intake and maintaining muscle mass, regular exercise helps with weight control—the risk of developing Alzheimer’s triples in people with a body mass index over 30.
  • Mental activity is as important as physical activity. Challenge yourself to learn something outside your comfort zone. This will stimulate and engage your brain.
  • Develop strong social relationships. Super-agers are social butterflies. The brain area responsible for sustaining attention is larger in Super-agers, and the nerve cells in this area are believed to play a role in social processing.
  • Super-agers drink alcohol in moderation.

The fact that your brain shrinks after 30 is not entirely a myth nor a cause for alarm. Some structural changes in the brain are inevitable with age but do not necessarily lead to cognitive decline. Adopting a healthy lifestyle and staying mentally and socially active can support your brain’s health and help it thrive well into your later years.

References

Bhandari, Tamara. “Smoking Causes Brain Shrinkage.” WashU Medicine, 12 Dec. 2023.

Budson, Andrew. “Can Physical or Cognitive Activity Prevent Dementia.” Harvard Health Publishing, 16 Sept. 2021.

Daviet, Remi, et al. “Associations between Alcohol Consumption and Gray and White Matter Volumes in the UK Biobank.” Nature Communications, no. 1, Springer Science and Business Media LLC, Mar. 2022.

Desai, Pankaja, et al. “Longitudinal Association of Total Tau Concentrations and Physical Activity With Cognitive Decline in a Population Sample.” JAMA Network Open, no. 8, American Medical Association (AMA), Aug. 2021.

Ducharme, Jamie. “5 Places Where People Live the Longest and Healthiest Lives.” Time Magazine, Feb. 2018.

“To Sleep, Perchance to Clean.” University of Rochester Medical Center, 17 Oct. 2013.

Wilson, Robert, et al. Cognitive Activity and Onset Age of Incident Alzheimer Disease Dementia. Neurology, 21 Aug. 2021.

Wnuk, Alexis. “How the Brain Changes With Age.” BrainFacts.Org, 30 Aug. 2019.

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