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Human Brains Are Getting Bigger, So Why Are Dementia Rates Rising?

Author:

Hannah Frye

April 15, 2024

Assistant Beauty & Health Editor

By Hannah Frye

Assistant Beauty & Health Editor

Hannah Frye is the Assistant Beauty Editor at mindbodygreen. She has a B.S. in journalism and a minor in women’s, gender, and queer studies from California Polytechnic State University, San Luis Obispo. Hannah has written across lifestyle sections including health, wellness, sustainability, personal development, and more.

Image by Marc Bordons / Stocksy

April 15, 2024

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More and more people are minding their brain health, especially if they've seen friends or family members struggle with cognitive decline. From dementia prevention games to memory supplements and optimizing sleep, we're learning how to put the brain first.

As it turns out, the brain itself may be changing too—getting bigger, as the latest research shows. But is this a good thing? And how does it related to dementia risk? Here's what it all means for your health.

The human brain is getting bigger, research suggests

The finding comes from a cross-sectional study published in the journal JAMA Neurology1. The research team analyzed data from the Framingham Heart Study cohort to explore trends in cranial and brain volumes and cortex thickness.

The 3,226 participants included in the study were born between 1930 and 1970, and MRI scans took place between 1999 and 2019, when the participants were an average age of 57 years old. As a prerequisite, they all had to be free from dementia or stroke history at the time of the scan.

The results from MRI scans show larger intracranial, hippocampal, and white matter volumes, as well as cortical surface area, in those born in later birth decades.

But what does the change in size mean?

The research team states that larger brain volumes indicate larger brain development and potentially greater brain reserve. They hypothesize that this leads to a decline in dementia.

brain guard+

"The volume of the region hippocampus is important, it plays a direct role in the preservation of memory," adds board-certified neurologist and integrative medicine doctor Dr. Romie Mushtaq, M.D.

She highlights that hippocampal volume loss typically correlates with early memory decline and is even linked to Alzheimer's disease. So the observed improvements in hippocampal volume from this study are a positive development and potentially a protective factor for brain health.

Why is dementia still on the rise then?

But this increase in brain size comes with a paradox, given that dementia is statistically on the rise. I asked board-certified psychiatrist and neuroscientist Dave Rabin, M.D., Ph.D., to explain how the brain could be getting larger, offering an improvement in dementia rates, yet the opposite is happening.

"The human brain is getting larger and smaller in different ways simultaneously," he says frankly. The shrinking he refers to is called synaptic pruning. This process takes place when the parts of the brain left underutilized get trimmed down, while other parts of the brain become larger and tighter the more they're utilized.

So if you zoom out and look at increasing rates of dementia, you'll realize it doesn't necessarily have to do with brain size—we now know that is working in our favor, if anything. Rather, it's social and environmental contributors that continue to elevate Alzheimer's risk.

Rabin identifies social isolation, lack of connections, and a deficiency in continuous learning as key reasons behind this increasing trend. Mushtaq agrees, adding high levels of stress and nutrition challenges for some groups to the list.

The bottom line? Increasing brain size is promising, but that alone won't fully cancel out the negative effects of other factors at play.

Summary

The increase in brain size may be protective of dementia. However, this change alone does not fully cancel out known risk factors for dementia (social isolation, poor nutrition, etc.), which is why dementia rates are still on the rise.

How to support your brain health starting today

So, we're back to the focus on brain health in the well-being space—an area that certainly deserves the attention it's getting. Nevertheless, recommendations can be confusing, so start with these simple action items:

Learn new things: "As we start to age, if we age and don't continue to challenge ourselves to learn new things and exercise our memory, just like exercising our muscles in the gym," Rabin says. So pick up a new hobby, find a topic that interests you and master it, or explore a new passion project—the goal is to learn something new, in any way you find enjoyable.
Prioritize social connection: We know that community is a direct feeder of longevity and mental health. While spending time with friends and family may seem frivolous compared to a head-down job or gym workout, you should view it as a part of your well-being routine too. Here, a few ways to strengthen your community.
Manage stress when possible: Too often, society glamorizes stress to be seen as proof you're working hard—but that will take a toll on your brain and full-body health. In pursuit of balance, work some stress-relieving activities into your day such as meditation, exercise, etc.
Consume brain-boosting nutrients: When it comes to diet and brain health, the overarching recommendation is to eat a balanced diet rich in nutrients. To go beyond that, you can add a few brain-boosting foods to your grocery list or consider a brain health supplement—here are the best options for the latter if you're curious.

Editor's note

There are still plenty of unknown reasons people develop Alzheimer's. And even with this evolutionary advantage of now having larger brains and a prioritization of brain-loving lifestyle habits, some things are still out of our control. Dementia should not be seen as something "caused" by one specific thing, nor is it something that is 100% preventable through lifestyle factors.

The takeaway

A recent study indicates that the human brain may be expanding, potentially offering a promising opportunity for reducing dementia rates. Nonetheless, experts emphasize the importance of addressing the social and environmental factors currently driving the increase in dementia cases. Here, five take-home tips to enhance your memory now and benefit your brain in the future.