Protecting brain health starts earlier than many people think, says neurologist Dr. David Perlmutter, who argues in his new book that tiny immune cells in the brain — microglia — are central to whether a brain remains healthy or becomes vulnerable to inflammation and neurodegenerative disease.
Metabolism and the brain: a close connection
Perlmutter, author of Brain Defenders: Harness the Power of Your Immune Cells to Protect Your Brain for Life, links rising rates of Alzheimer's disease to declines in population metabolic health. He notes that there are currently 7.6 million people diagnosed with Alzheimer’s in the United States and says that number is growing in tandem with worsening metabolic markers.
"We have 7.6 million Alzheimer's patients diagnosed in America today, and that number is growing dramatically," Perlmutter said.
His argument centres on the role of microglia — specialised immune cells in the brain — which he says can either help maintain brain health or, when activated by metabolic stressors, contribute to chronic inflammation that precedes neurodegeneration.
Which risk factors matter?
Perlmutter emphasises that Alzheimer’s and related conditions are tightly related to metabolic factors. He points to several commonly measured health markers as influential in shaping microglial behaviour and, by extension, long-term brain health:
- Elevated blood sugar
- Elevated blood pressure
- Excess body fat
According to Perlmutter, these conditions contribute to the activation of microglial cells, which then play a pivotal role in either preserving cognition or setting the stage for decline.
What this means for people now
Perlmutter’s prescription is prevention: he argues that because current treatments for Alzheimer’s are limited, the priority should be on reducing metabolic risk earlier in life. While his book digs into mechanisms and strategies for harnessing microglia, the central public-health takeaway is simple — metabolic health matters to the brain.
From a lifestyle perspective, the implication is that measures known to improve metabolic markers could also be protective for brain health. These measures commonly recommended by clinicians and public-health bodies include diet quality, regular physical activity, blood-pressure control and management of blood sugar and weight. Perlmutter frames such approaches as ways to "shift our metabolism" and thereby influence brain immune cells in a favourable direction.
| Risk factor | Implication for microglia / brain health |
|---|---|
| Elevated blood sugar | Contributes to activation of microglia, increasing vulnerability to inflammation |
| Elevated blood pressure | Associated with metabolic decline that may influence microglial behaviour |
| Excess body fat | Linked to metabolic dysregulation and microglial activation |
Practical steps and considerations
For readers looking to take action, the message is to treat metabolic health as part of brain-health planning across adulthood rather than an issue only for later life. Practical, broadly accepted steps include:
- Regular monitoring of blood pressure and blood sugar;
- Adopting dietary patterns that support healthy glucose and lipid levels;
- Maintaining regular physical activity and a healthy body composition;
- Discussing metabolic risk with a primary-care provider and following recommended screening.
Perlmutter also personalises his motivation: his father, Dr. Irwin Perlmutter, died from complications of Alzheimer’s, which he says spurred his work to find ways of protecting future generations. That personal connection underlines the urgency he sees in addressing metabolic health now, not later.
While research continues into the precise ways microglia and metabolism interact, the current guidance is pragmatic: improving metabolic health may be one of the most actionable ways to reduce long-term risk for cognitive decline. For those who want to prioritise brain health, focusing on metabolic markers offers a measurable, evidence-aligned route to potentially lower future risk.
