Dopamine Genes & Biomarkers — Suboptimal Factors & Actions Gene / Biomarker Suboptimal / Limiting Factor Free Actions Non-free Actions GENES BIOMARKERS DRD2Low receptor density (Taq1A)Exercise, cold exposureD2 agonist therapy DRD4Reduced sensitivity (7R allele)Novelty, varied routinesStimulant medication COMTFast breakdown (Val158Met)Stress reduction, sleepCOMT inhibitors (Rx) DAT1Rapid reuptake (10R allele)HIIT, intermittent fastingNDRI therapy MAOAAltered catabolism (low activity)Sunlight, aerobic exerciseMAO inhibitor (supervised) Urinary dopamineLow excretion (<120 µg/day)Tyrosine-rich foodsL-DOPA precursors Plasma dopamineLow baseline (<20 pg/mL)Daily aerobic exerciseBupropion (Rx) HVA (urine)Low metabolite (<2 mg/day)Cold shower, fastingMucuna pruriens ProlactinElevated (>20 ng/mL = low DA)Stress managementCabergoline (Rx) Plasma tyrosineLow precursor (<50 µmol/L)Meat, eggs, legumesL-Tyrosine supplement PhenylalanineLow precursor (<40 µmol/L)Protein-rich dietDLPA supplement