🧠 Rethinking Brain Aging: Why Your Mind Might Be Smarter Than Evolution Thinks

We’ve long been told that aging is a slow, inevitable decline—our cells wear out, our systems falter, and we gradually lose the capacity we had in youth. Evolution, the story goes, has no reason to protect us after we’ve passed our reproductive prime. This belief is embedded in the widely cited Disposable Soma Theory (DST), which argues that after reproduction, the body becomes… well, disposable.

But what if the brain didn’t get the memo?

A compelling new perspective by Bruno Feltes, published in Biogerontology, argues that the human brain may defy the rules. Instead of a uniform downhill slide, Feltes presents evidence that the brain follows a selective resilience trajectory—actively protecting certain high-function areas, even in late life. And this has profound implications for how we understand resilience, aging, and chronic disease.

🌿 The Resilient Brain: Not a Passive Decline, but an Active Reorganization

Feltes highlights how, despite being metabolically expensive, certain brain regions like the hippocampus, prefrontal cortex, and hypothalamus continue to maintain high functionality in old age. Why? Because these regions support memory, social interaction, emotional regulation, and adaptive cognition—functions that matter far beyond reproduction.

Rather than shutting down, these regions:

• Switch to ketone body metabolism during energy scarcity

• Use pyruvate and astrocyte-derived lactate as fuel and antioxidants

• Preserve NAD⁺, a molecule critical for redox balance and DNA repair

• Show increased estrogen receptor sensitivity in postmenopausal women, helping preserve cognitive and emotional functions

This isn’t somatic neglect—it’s selective investment.

🔁 CACH: The Cycle Behind Resilience

This insight aligns with the proposed model of Catabolic-Anabolic Cycling of Hormesis (CACH): the body adapts by oscillating between breakdown and repair cycles, shifting energy and resources based on context and availability.

In the brain:

• Fasting or caloric restriction promotes ketone-based energy and activates protective stress responses.

• Recovery periods allow for synaptic remodeling, neurogenesis, and redox repair.

• Neurons, despite their long life and high demands, remain remarkably responsive to substrate switching.

Aging, then, isn’t a single straight line of loss—it’s a series of metabolic shifts, where adaptive systems are prioritized, especially when fuel is scarce.

🧠 BEC: The Brain-Body Energy Conservation Framework

Feltes’ findings map directly onto what we call the Brain-Body Energy Conservation (BEC) model. In this view, the body doesn't degrade uniformly. Instead, it preserves the brain's most valuable circuits—those involved in communication, social survival, and intergenerational support, often at the expense of declining peripheral functions.

From Feltes' perspective, we start to get more details on brain-specific energy conservation strategy as:

• Region-specific (not all areas are preserved equally)

• Fuel-flexible (uses ketones, lactate, pyruvate)

• Hormone-responsive (estrogen signaling persists)

• Glia-supported (astrocytes help buffer neurons)

This helps explain why many older adults retain wisdom, emotional insight, and creativity, even as physical stamina or peripheral functions decline. The brain protects what matters most—for the individual and for the community.

🍽️ ERM: What Happens When the Energy Isn’t Enough?

Here’s where things get practical. Our framework of Exposure-Related Malnutrition (ERM) suggests that mild, chronic underfueling of resilience systems—even in the absence of obvious weight loss—can lead to subtle but impactful decline.

Feltes’ work helps explain:

• Why symptoms like brain fog, poor memory, and mood issues appear even before structural damage

• How redox imbalance and NAD⁺ depletion may quietly undermine neuronal resilience

• Why maintaining fuel flexibility (e.g., through fasting, ketone adaptation, and nutrient diversity) can be crucial in aging or illness

When energy is scarce—or when mitochondrial efficiency declines—the brain may no longer be able to uphold its prioritized functions, leading to the subtle early-stage patterns we identify as ERM.

💡 Takeaway: Resilience Is Strategic, Not Random

This paper reinforces what emerging systems biology is telling us: aging is not entropy—it’s economy. The brain doesn't passively decay; it strategizes, reallocates, and conserves.

The implications are powerful:

• Aging interventions should focus not just on preventing disease, but on supporting the body’s natural prioritization strategies.

• Nutrients like NAD⁺ precursors, pyruvate, and SCFA-producing fibers may act as resilience adjuvants.

• We need to shift our narrative from "decline" to dynamic adaptation.

📚 Reference

Feltes, B. C. (2025). Selective resilience in brain aging: challenging the scope of the disposable soma theory. Biogerontology, 26:152. https://doi.org/10.1007/s10522-025-10292-1

🧭 Final Thoughts

You are not disposable.

Your body is not broken—it’s doing the best it can with what it has.

The more we understand the logic behind aging, the better we can work with our biology to support cognitive and emotional vitality across the lifespan.

In the words of this paper: "Brain aging is better described not as somatic neglect, but as adaptive redistribution."

We agree !

#Selective Resilience, #Brain Aging, #Energy Reallocation, #NAD⁺ Metabolism, #Exposure-Related Malnutrition (ERM)