What this means

COMT (catechol-O-methyltransferase) breaks down dopamine in the prefrontal cortex. The Val158Met variant (rs4680) changes a single amino acid that affects how thermally stable the enzyme is — the Val version clears dopamine about 3–4x faster than the Met version. The popular framing is "warrior versus worrier": Met/Met carriers tend to do slightly better on working-memory tasks at rest, but Val/Val carriers tend to hold up better under acute stress. As with most cognitive-genetics findings the effect sizes are modest and replications have been uneven.

The COMT enzyme clears dopamine out of the front of your brain — the part most involved in planning, focus, and managing stress. A common DNA change comes in two versions: one clears dopamine three to four times faster than the other. The popular framing is "warrior versus worrier": the slow version often comes with slightly better working-memory at rest but more sensitivity to stress; the fast version often holds up better when things get acutely stressful. The effect on any one person is small though, and the findings haven't always replicated cleanly.

Caveats

• Effect sizes on cognition and stress are small and have not always replicated.
• The "warrior/worrier" framing is a useful metaphor, not a personality test.
• Many other genes shape dopamine signalling — this is one variable in a system.
• Sleep, mood, and context affect prefrontal function far more than any single SNP.

References

• Egan et al. — Effect of COMT Val108/158Met genotype on frontal lobe function and risk for schizophrenia (PNAS, 2001)
• Mier et al. — Neural substrates of pleiotropic action of genetic variation in COMT: a meta-analysis (Molecular Psychiatry, 2010)