David Perlmutter, M.D.

What’s Inside the Immersion Course The Immersion Course is structured around four core components, each designed to take readers from understanding the science to living it. Together, they form the most direct path from reading Brain Defenders to actually changing outcomes. Dr. Perlmutter personally walks through Brain Defenders section by section, breaking down what to focus on, what the science actually means, and what matters most in each chapter. Readers never go through the material alone.

For years, Parkinson’s disease has been viewed primarily as a disorder of the brain. But an extraordinary new study published in Nature Medicine suggests that some of the earliest biological clues may actually be found much farther south, in the gut. Researchers analyzed the gut microbiomes of more than 460 individuals, including people with Parkinson’s disease, healthy controls, and individuals carrying GBA1, the strongest known genetic risk factor for Parkinson’s disease.

If it feels like everyone is talking about Ozempic, Wegovy, Zepbound, or Mounjaro these days, you’re not imagining things. What began as a treatment for type 2 diabetes has become a cultural phenomenon. Millions of people are now taking GLP-1 receptor agonists, primarily for weight loss, and demand has exploded worldwide.

For decades, the search for the cause of Alzheimer’s disease has focused on genes, amyloid plaques, and the promise of new medications. But a growing body of research is revealing something far more immediate—and far more actionable. One of the most powerful influences on dementia risk may not be hidden deep within our biology. It may be sitting on our plates every single day. The culprit? Ultra-processed foods.

Whenever I give talks about brain health, someone almost always asks a version of the same question: “How can I get the benefits of good sleep if I have to work at night?” It’s a great question because millions of people don’t have the option of sleeping when it’s dark outside. Nurses, doctors, paramedics, police officers, firefighters, pilots, truck drivers, factory workers, and many others work through the night to keep our communities running.

For decades, one of the most striking and often overlooked features of Alzheimer’s disease is this: it affects women about twice as often as men. Why would that be? Is it simply that women live longer? Hormones? Genetics? Or is something deeper going on inside the brain? A fascinating study published in Communications Biology sheds light on this mystery by focusing on one of the most important players in brain health: microglia, the brain’s resident immune cells.

We tend to think of emojis as harmless, simple digital decorations that soften language, add humor, or clarify tone. But emerging neuroscience suggests something far more consequential. A recent EEG-based study reveals that when we see emojis, whether happy, sad, or angry, the brain processes them using neural pathways strikingly similar to those engaged when we interpret real human facial expressions.

As many of you know, my wife and I recently had the incredible opportunity to visit Antarctica. It is difficult to adequately describe the experience of arriving in a place so vast, so pristine, and so profoundly removed from the rhythms of everyday life. There is an immediate and humbling sense that you are entering one of the last truly wild frontiers on Earth. The scale alone is breathtaking with endless expanses of ice, towering glaciers, and an unfamiliar silence that feels almost sacred.

At first glance, autism and Alzheimer’s disease appear to exist at opposite ends of the neurological spectrum, one a condition of early brain development, the other a disease of later-life degeneration. But as our understanding of brain biology deepens, a compelling unifying idea emerges: these two conditions may, in fact, share a common underlying mechanism.

A fascinating new study explores a topic I have written about many times before: the brain’s waste clearance system, known as the glymphatic system. As I have discussed in previous blogs, one of the most important reasons to get adequate deep sleep is that this is when the glymphatic system is most active. During deep, slow-wave sleep, cerebrospinal fluid washes through the brain and helps clear away metabolic debris, including proteins linked to neurodegenerative diseases.