Your Stress Never Stops. Your Genes May Be Why.

COMT (catechol-O-methyltransferase) is the enzyme responsible for breaking down dopamine, norepinephrine, and epinephrine. It’s your nervous system’s off switch. When COMT is working normally, it degrades these stress hormones efficiently so they don’t accumulate and keep your nervous system in a heightened state.

The Val158Met variant creates a slow-acting version of COMT. People carrying this variant, particularly those homozygous for the slow allele, have roughly 40% less enzyme activity. That means stress hormones linger in your bloodstream longer, keeping your nervous system activated even after the stressor is gone. You clear dopamine slowly as well, which further impairs your ability to shift from stress mode to rest mode.

Day to day, this feels like: your nervous system won’t downshift. A stressful meeting stays with you for hours. You feel wired and agitated even in the evening. Caffeine triggers anxiety because your dopamine stays elevated. You’re sensitive to stimulation. Your thoughts race. Relaxation feels difficult or impossible to achieve.

SLC6A4 encodes the serotonin transporter, the protein responsible for recycling serotonin back into neurons after it has done its job signaling. Think of it as the reuptake pump: once serotonin is released and binds to a receptor, the transporter pulls it back inside so it can be reused or metabolized. Without efficient recycling, serotonin availability drops and resilience to stress collapses.

The short allele of the 5-HTTLPR polymorphism reduces transporter expression and efficiency. People carrying at least one short allele have impaired serotonin recycling, leaving them with less available serotonin and heightened reactivity to emotional threats. This isn’t because they’re making less serotonin; it’s because they’re not retaining what they make. The result is a nervous system that perceives risk more readily.

Day to day, this shows up as: heightened anxiety in response to minor social cues; persistent worry that doesn’t match the actual threat level; difficulty recovering emotionally after stressful events; a sense that you’re more fragile than others around you; rumination that you can’t easily interrupt.

TPH2 (tryptophan hydroxylase 2) catalyzes the first committed step in serotonin synthesis within the brain. It converts tryptophan into 5-hydroxytryptophan (5-HTP), which is then converted to serotonin. Without this enzyme, you can’t make serotonin in the brain tissue that uses it, regardless of how much dietary tryptophan or supplement precursors you consume.

Variants in TPH2 reduce enzyme activity, directly lowering the rate-limiting step in brain serotonin production. People with TPH2 variants produce less serotonin in the brain where mood and stress regulation live, even if peripheral serotonin levels appear normal on bloodwork. This is why standard serotonin biomarkers often miss the problem: serotonin synthesized in the gut doesn’t cross the blood-brain barrier effectively.

You experience this as: persistent low mood that isn’t situational depression but a baseline flatness; reduced ability to feel pleasure or reward from normally enjoyable activities; poor stress resilience even when objectively your life is stable; a sense of emotional numbness; anxiety that coexists with emotional flatness.

MTHFR encodes methylenetetrahydrofolate reductase, the enzyme that activates folate into the form your cells actually use for methylation reactions. Methylation is the chemical process that synthesizes dopamine, serotonin, norepinephrine, and the neurotransmitter acetylcholine. Without active folate, you can’t make these molecules efficiently, regardless of how much you eat or supplement.

The C677T variant reduces MTHFR enzyme activity by 35-50%, depending on whether you’re heterozygous or homozygous. This creates a functional folate deficiency at the cellular level, leaving you unable to synthesize adequate dopamine, serotonin, and norepinephrine even with a diet full of folate. You’re not folate deficient on bloodwork; you’re functionally unable to use the folate you have.

This manifests as: profound brain fog and cognitive sluggishness; difficulty concentrating or sustaining attention; mood instability and emotional flatness; anxiety that feels physiologically based rather than situational; fatigue despite adequate sleep; slow processing speed and difficulty finding words.

GAD1 encodes glutamate decarboxylase 1, the enzyme that converts glutamate (an excitatory neurotransmitter) into GABA (the primary inhibitory neurotransmitter). GABA is your nervous system’s brake pedal. It suppresses excessive neuronal firing and creates the felt sense of calm. Without adequate GABA production, your nervous system becomes hyperexcitable.

Variants in GAD1 reduce enzyme activity, lowering GABA production throughout the brain. This means your nervous system has less inhibitory tone, making it easier to tip into anxiety, hypervigilance, and racing thoughts. You’re producing an excess of excitatory signaling that nothing is suppressing.

You feel this as: baseline anxiety that isn’t triggered by anything specific; racing thoughts you can’t turn off; physical restlessness and agitation; difficulty achieving a sense of calm even in safe environments; hypersensitivity to sensory input (sound, light, touch); a feeling that your nervous system is always partially activated.

MAOA (monoamine oxidase A) breaks down dopamine, serotonin, and norepinephrine after they’ve been released and acted on their receptors. It’s a cleanup enzyme. When MAOA is working normally, it degrades these neurotransmitters at a steady rate, maintaining stable levels. When MAOA activity is low, these neurotransmitters accumulate and fluctuate unpredictably.

The MAOA-L variant (low activity allele) occurs in roughly 30-40% of males (females typically have two X chromosomes, so the genetics is more complex). People with MAOA-L have reduced monoamine degradation, leading to higher, more variable neurotransmitter levels and heightened emotional reactivity to minor stressors. The same trigger creates a larger neurochemical response and a longer recovery time.

This creates: intense emotional reactions to small provocations; mood swings and emotional lability; difficulty recovering from emotional activation; aggressive or impulsive responses under stress; hypervigilance to threat cues; a sense of being emotionally volatile.