🧠 When the Brain Runs on Empty: The Allostatic Triage Model and the Energy Cost of Mental Health

A new perspective from neuroscience is reshaping how we understand stress and mental illness — not as a chemical imbalance, but as an energetic imbalance.

A recent paper in Neuroscience & Biobehavioral Reviews by Kelley and colleagues (2025) introduces the Allostatic Triage Model of Psychopathology (ATP) — a unifying theory that sees the brain as an energy-allocating organ.

Under stress, it must decide which functions get powered and which are temporarily “dimmed” to conserve energy.

🔋 The Brain’s Energy Economy

Every thought, emotion, and movement depends on a steady supply of ATP — the body’s cellular currency of energy. When we face a stressor, energy demands spike: the heart races, glucose floods the bloodstream, and the brain shifts into high alert.

But if these demands persist without enough time or resources to recover, the brain begins to triage. Like an emergency hospital during a blackout, it must decide which circuits stay online.

According to the ATP model, three major brain networks compete for limited energy:

1. The Salience Network (SN) — scans for danger and threat.

2. The Central Executive Network (CEN) — governs reasoning, focus, and planning.

3. The Default Mode Network (DMN) — supports reflection, creativity, and self-integration.

In chronic stress, the SN dominates. Energy and glucose are rerouted toward vigilance and away from higher cognitive functions — producing symptoms that look familiar to anyone living with anxiety, depression, or burnout:

• Racing thoughts, restlessness, insomnia

• Cognitive fatigue, brain fog, forgetfulness

• Emotional numbness or overreactivity

• Difficulty recovering after stress

This isn’ta weakness. It’s the brain’s adaptive austerity plan — an act of survival under energy shortage.

⚙️ The Molecular Machinery Behind “Energy Triage”

At the cellular level, this triage is governed by bioenergetic sensors that monitor and redistribute energy in real time:

Molecular System	Role in Triage	Clinical Consequence
AMPK (AMP-activated protein kinase)	Detects falling ATP levels and suppresses energy-costly activities like growth or repair	Fatigue, poor recovery, muscle loss
SIRT1/NAD⁺ System	Tunes mitochondrial renewal and circadian rhythm	Low resilience, sleep disturbance
Mitochondrial Distress Signals (GDF15, FGF21)	Warn the body of energy crisis, triggering appetite and activity suppression	Appetite loss, malaise, “crash” after overexertion
Glucocorticoids & Catecholamines	Shift metabolism toward fast energy (glucose), suppress long-term repair	Anxiety, hypervigilance, cognitive rigidity

Under prolonged stress, mitochondria — the cell’s energy producers — shift from oxidative phosphorylation (efficient, steady ATP generation) to glycolysis (fast but wasteful).

This “short-term gain, long-term loss” metabolism mirrors the person who lives on borrowed energy — surviving on coffee and adrenaline while skipping rest and recovery.

🧬 From Brain Networks to Body Systems: The ERM Connection

The Allostatic Triage Model describes what happens inside the brain, but its logic extends across the entire body — a perspective captured by the Exposure-Related Malnutrition (ERM) framework.

ERM views chronic stress, inflammation, and environmental exposures as forces that drain the body’s energy reserves faster than they can be replenished. The result is a demand-driven energy debt that manifests in every system:

System	Energy Trade-Off	Consequence
Brain	Vigilance prioritized over reflection	Anxiety, brain fog, poor concentration
Immune	Inflammation prioritized over tolerance	Chronic low-grade inflammation
Muscle	Mobilization prioritized over repair	Weakness, sarcopenia
Gut–Liver Axis	Detoxification prioritized over digestion	Dysbiosis, nutrient loss

From the ERM perspective, mental illness is not separate from metabolic stress — it’s one of its most visible expressions. The same energy shortage that makes muscles weak and immunity erratic also leaves the brain stuck in a defensive loop, unable to relax, reflect, or renew.

🔄 The Common Thread: Incomplete Recovery

Both models — ATP and ERM — converge on a single insight:

Health is not just the ability to respond to stress, but the capacity to recover from it.

When recovery is incomplete, the body and brain remain in a “half-adapted” state — surviving, not thriving. Mitochondria stay in emergency mode, and neurons stop investing in long-term plasticity.

Over time, this becomes the biology of burnout, depression, and cognitive decline.

🌱 Restoring the Energy Cycle

Clinically, this perspective shifts the question from “What chemical is missing?” to “What energy is missing, and why can’t recovery complete?”

Key therapeutic goals include:

• Restoring circadian rhythm — because mitochondria recharge in synchrony with light and sleep.

• Repleting metabolic cofactors (NAD⁺, magnesium, B vitamins, amino acids) that support mitochondrial recovery.

• Balancing neuroinflammation through diet, antioxidants, and stress management.

• Promoting hormesis — short, controlled stress (exercise, cold, fasting) followed by full recovery.

These are not just lifestyle tips; they are bioenergetic interventions to re-establish the adaptive rhythm:

Respond → Adapt → Resolve → Renew.

🧩 In Essence

The Allostatic Triage Model reveals that when energy becomes scarce, the brain performs triage — diverting power from reflection and repair toward survival.

The ERM framework expands this to the whole body, showing how chronic energetic debt erodes the resilience system-wide.

Together, they tell a simple but profound story:

We don’t burn out because we’re weak. We burn out because we’ve spent too long in survival mode without enough energy to heal.

References

Kelley, A. E., et al. (2025). The Allostatic Triage Model of Psychopathology. Neuroscience & Biobehavioral Reviews, 179, 106419.