ADHD is a clinical label for attention and impulse patterns: restlessness, distractibility, and difficulty sustaining focus, most often diagnosed in childhood. ADHD maps to an energy-supply problem specific to the frontal lobes rather than a fixed trait or a chemical imbalance of unknown origin: the newest, highest-energy-requiring part of the brain runs short of fuel, and stimulant drugs, sugar, and thyroid hormone all work by supplying more of it. Stimulant drugs raise catecholamines and blood sugar. Sleep, sugar stability, thyroid, and light strongly affect attention capacity.

ADHD
Synonyms Attention-deficit/hyperactivity disorder, hyperkinetic syndrome
Classification Psychiatric
Metabolic driver Frontal-lobe energy deficit
Standard treatment Stimulants (methylphenidate, amphetamines)
Ray's verdict "Not enough energy is being supplied to permit this tissue to function properly"

Why stimulants work

[edit]

Low blood sugar is itself a driver of restless, hyperactive behavior. Amphetamines and caffeine both raise blood sugar by mimicking the sympathetic "alarm" response, which is part of why they calm hyperactive behavior instead of worsening it.[1] The "paradoxical" calming effect of stimulants on hyperactive children isn't paradoxical once the frontal lobes are understood as the most energy-hungry, and therefore most easily under-fueled, part of the brain:

Since the 1960s, a stimulant, Ritalin (methylphenidate) has often been prescribed for hyperactive kids, because it made them able to quietly pay attention. This effect was called "paradoxical," but for scientific physiology there was nothing paradoxical about it. The frontal lobes of the brain, the most highly evolved part, give us the ability to plan and to understand complex things that require prolonged attention. Without this higher part of the brain, which has a very high energy requirement, people and animals become hyperactive and unable to concentrate. Ritalin (or coffee) makes anyone, even the brightest students, more attentive and focused. Caffeine and Ritalin temporarily raise the energy level of the brain.

— Ray Peat[2]

The frontal lobes are also the part of the brain that lets an animal or person disregard irrelevant stimuli rather than reacting to everything at once; A.R. Luria's dogs with frontal-lobe damage lose exactly this capacity, being unable to inhibit orienting reflexes to distracting stimuli: the animal model for an under-fueled frontal lobe.[3] Coffee, unlike other stimulants, also activates the thyroid gland, which is the more sustainable route to the same energy supply.[1]

Amphetamines mimic the action of the "alarm" part of the nervous system (sympathetic) and so raise the level of blood sugar; this is probably the mechanism (or part of it) which suppresses appetite. Low blood sugar is associated with hyperactivity, and this is probably why the same drug is effective for the hundreds of thousands of crazy kids who get it so they will sit still in school; coffee works as well in hyperactivity, and might also help dieters.

— Ray Peat[4]

Three theories of what causes hyperactivity, low blood sugar, weak radiation from fluorescent lights and TV, and food additives, converge on the same energy-deprivation picture, since anything that stresses nerve tissue raises its energy requirement past what's being supplied.[3] The popular food-dye/additive theory (the Feingold diet) is a weak account: additives usually travel with low-quality, high-sugar food, so the sugar itself is the more plausible driver of low blood sugar and hyperactivity, not the dye.[3]

Three studies bear on this framing:

  • In a rat model of ADHD (neonatal 6-OHDA lesioning), caffeine improved the attention deficit; the authors hypothesized caffeine could help manage attention deficit during the prepubertal period of ADHD. This is animal-model evidence, not a human trial.[5]
  • In adolescent spontaneously hypertensive rats (SHR), chronic caffeine normalized elevated frontocortical and striatal dopamine transporter density and dopamine uptake and improved attentional set-shifting and Y-maze performance; matched WKY controls showed no caffeine effect on those measures.[6]
  • In 342 healthy 4-year-olds, higher TSH within the normal range was associated with lower cognitive function, and high TSH with low free T4 was associated with ADHD symptoms.[7]
  • In a controlled trial of 50 children with ADHD, vitamin D supplementation improved cognitive function, inattention, opposition, hyperactivity, and impulsivity domains versus controls.[8]

Chronic-use risks

[edit]

Any drug that boosts the adrenaline system creates stress that harms the whole body, not just the brain function it's aimed at, because the brain is an interlocking system: pushing one function forces a global readjustment as the rest of the brain adjusts under stress. Chronic amphetamine addicts show terrible brain damage and probable brain shrinkage as a result.[9]

As far back as the late 1960s, researchers were noting a connection between amphetamines and lymphoma.[9][10]

It happens that as far back as the late 1960s, people were noticing a connection between amphetamines and lymphoma. I was aware of that because I had a close friend who loved his Benzedrine and died in his 40s from lymphoma. Lately, more people are recognizing that lymphoma is the result of toxic stress.

— Ray Peat[11]

Thyroid hormone

[edit]

Hypothyroidism and low thyroid hormone activity cause ADHD. T3 improves ADHD symptoms specifically in children whose tissues resist thyroid hormone. Thyroid hormone and its cofactor magnesium supply the energy for the deprivation problems that include hyperactivity: "no one would hesitate to use thyroid hormone (and its energy-associated co-factor, magnesium) for insomnia, hyperactivity, and the whole range of energy-related problems."[12]

Children who are given amphetamines to keep them quiet in school don't grow as fast as they should, and remain permanently stunted even after stopping the treatment. This kind of drug can be addicting, resulting in decreased alertness when the drug is stopped. Hormonal compensation is likely to be involved, so it would seem reasonable to check at least the thyroid function in children who have been subjected to amphetamine treatment; it might help them catch up in mental and physical growth.

— Ray Peat[13]

Higher TSH within the normal range generally indicates lower thyroid hormone output or a problem with thyroid hormone metabolism.[7]

Resistance to thyroid hormone (RTH) is a condition in which tissues respond less than normal to T3 even though blood thyroid hormone levels may be high or normal, usually from mutations in the thyroid hormone receptor beta (TRβ / THRB) gene. Because the receptor doesn't respond properly, affected cells "see" less thyroid hormone action than they should, the same functional shortfall seen in ordinary hypothyroidism, or in impaired thyroid hormone conversion and tissue uptake that blood tests can miss. In a National Institutes of Health study of 104 patients with RTH from 42 kindreds, compared with 114 unaffected relatives, RTH patients had markedly higher rates of goiter (65%), ADHD (60%), IQ under 85 (38%), speech impediment (35%), and short stature (18%).[14]

A placebo-controlled crossover trial gave T3 (liothyronine) to children with ADHD, comparing 8 who also had RTH against 9 with normal thyroid function. T3 had no effect on hyperactivity ratings in 7 of the 9 ADHD-only children. In contrast, 5 of the 8 ADHD+RTH children improved, and T3 was associated with fewer impulsive "commission errors" on a continuous performance test in 4 of 7 ADHD+RTH children.[15]

In children with resistance to thyroid hormone and ADHD, particularly those that exhibit hyperactivity, T3 in supraphysiological doses may be beneficial in reducing hyperactivity and impulsivity. In the majority of children with ADHD who do not have RTH, T3 treatment has no effect or may be detrimental.

— Weiss, Stein & Refetoff[16]

TRβ-deficient mice show ADHD-like high exploratory activity with reduced habituation, low dopamine metabolic rates in caudate putamen and nucleus accumbens, and overall low serotonin metabolic rates; TRα-disrupted mice lack this monoamine pattern.[17]

Brain glucose metabolism

[edit]

Adults with childhood-onset hyperactivity show reduced glucose metabolism, both global and regional, with the largest reductions in the premotor cortex and superior prefrontal cortex, the same regions responsible for attention and motor control.[18] thyroid hormone regulates brain glucose metabolism, in part by controlling GLUT1/GLUT4 glucose transporter expression and by combining with insulin signaling through the PI3K/Akt-mTOR pathway to move glucose transporters to the cell membrane.[19]

A follow-up PET study of teenagers with ADHD from the same NIMH lab found no significant difference in whole-brain glucose use; only a few regions were lower, including a left frontal area whose lower metabolism tracked worse symptoms.[20]

Brain hypometabolism is common across thyroid disorders generally. Severe short-duration hypothyroidism produces a significant, global decrease in brain glucose metabolism; milder hypothyroidism reduces regional glucose metabolism specifically in the hippocampus, bilateral amygdala, and anterior, subgenual, and posterior cingulate cortex, and this reverses with thyroid hormone replacement.[19] A cross-sectional PET study of thyroid cancer patients four weeks after stopping levothyroxine, a deliberately induced transient hypothyroidism, found more depression and anxiety symptoms than patients kept on hormone replacement, alongside abnormal regional cerebral glucose metabolism on brain imaging.[21]

CO2 and carbonic anhydrase

[edit]

Raising brain CO2 may itself improve ADHD symptoms. In spontaneously hypertensive rats (the best-validated animal model of ADHD), the carbonic anhydrase inhibitors acetazolamide and methazolamide, which slow CO2's conversion to bicarbonate and so let CO2 build up slightly in tissue, significantly reduced hyperactivity (open-field locomotor test) and impulsivity (electro-foot-shock aversive water-drinking test) specifically in the ADHD-model rats, with no effect in normal control rats, and without impairing spatial learning on the Morris water maze at low doses.[22]

GABA

[edit]

MRS spectroscopy found reduced GABA concentration in the sensorimotor and other cortical regions of children with ADHD compared to controls.[23] This GABA finding is a separate line of evidence from the energy-supply account, not a replacement for it. See GABA.

Intracellular calcium-handling regulators SERCA2, ryanodine receptors (RyRs), IP3 receptors (IP3Rs), and parvalbumin (PVALB) are implicated in ADHD as in autism and schizophrenia.[24] See Calcium.

Amlodipine, an L-type calcium channel blocker, reduced hyperactivity in spontaneously hypertensive rats and reduced hyperactivity and impulsivity in a knockout zebrafish model of ADHD. In the same 2025 paper, drug-target Mendelian randomization tied ADHD to variants in the L-type channel subunits amlodipine binds (CACNA1C, CACNB1, CACNA2D3). In UK Biobank participants, amlodipine prescription was associated with fewer reports of mood swings and risk-taking after accounting for ADHD polygenic risk score. Eight of the 12 authors declared company employment. The evidence is animal, genetic and observational; no ADHD trial of amlodipine is reported.[25]

GABA is synthesized from glutamate by glutamic acid decarboxylase (GAD65 and GAD67), and thyroid hormone regulates GAD expression in the brain. In hypothyroid rat pups, hippocampal GAD65 protein fell to less than half of control levels and recovered fully with thyroxine replacement after birth.[26] Low thyroid function lowering GAD activity, and so GABA output, is a plausible mechanistic link between the low thyroid state and the low GABA state both independently documented in ADHD, though no clinical trial has yet tested T3 as a treatment through this specific pathway.

In spontaneously hypertensive rats (SHR), a high dose of taurine cut horizontal locomotion versus SHR controls, while a low dose raised it; both low and high doses lowered serum IL-1β and CRP in SHR, and high-dose taurine reduced hippocampal functional-connectivity and mALFF signals on resting-state fMRI in WKY and SHR.[27] A follow-up found high-dose taurine raised spontaneous alternation and lowered striatal dopamine transporter level and dopamine uptake in SHR (low dose did the opposite on uptake), with higher striatal BDNF on both doses.[28] Discussion of that work frames the behavioral change through GABA, dopamine, and glutamate pathways (including extrasynaptic GABA-A and nucleus accumbens dopamine); this is animal-model evidence, not a human ADHD trial.

Prenatal origins

[edit]

Prenatal and perinatal injury is a major driver of the rise in childhood hyperactivity since the mid-20th century, not just a postnatal diet-and-lifestyle problem: "since the mid-1950s, there has been a terrible increase in the incidence of hyperactivity in children, as discussed by Tom Brewer, largely because of prenatal injury," with the rising dietary use of unsaturated vegetable oils compounding it by interfering with thyroid secretion, transport, and tissue response.[12] A study he cited found a clear association between minor physical defects and hyperactivity, implicating "gestational stress," hormone imbalance and malnutrition during pregnancy, as a shared cause of both; the resulting damage can affect either the child's brain directly or its hormone regulation, low thyroid and high estrogen specifically, with damaged girls tending toward passivity and damaged boys toward hyperactivity.[3]

In a large Israeli birth cohort, children of mothers who had ever had hypothyroidism were about a quarter more likely to have autism spectrum disorder; the fetal thyroid gland isn't yet functional during early pregnancy, making maternal thyroid hormone supply the only source for early brain development.[29] ASD and ADHD share substantial genetic and environmental risk overlap; maternal hypothyroidism fits the same prenatal-injury pattern.

In a Welsh population cohort (observational), prenatal antidepressant exposure (mostly SSRIs) went with roughly double the rate of later ADHD diagnosis. Untreated maternal depression also raised the rate. Among mothers with depression, the extra risk from taking antidepressants was not significant. The cohort lacked depression-severity data.[30]

Dopamine reward pathway

[edit]

Nonmedicated adults with ADHD showed lower dopamine transporter and D2/D3 receptor binding than controls in nucleus accumbens, midbrain, and left caudate on PET. Attention ratings tracked D2/D3 binding in those regions.[31] Trait motivation (MPQ Achievement) scored lower in ADHD adults and correlated with midbrain and accumbens D2/D3 and with accumbens DAT within the ADHD group, not in controls.[32]

Altitude and dopamine

[edit]

Statewide ADHD prevalence in the US decreases with increasing average altitude, roughly 0.001 percentage points lower per foot of elevation across two independent national datasets. One proposed mechanism is that hypobaric hypoxia at altitude raises dopamine output as a compensatory response, and higher dopamine is protective against ADHD.[33] A competing analysis of the same pattern argues altitude is a proxy for sunlight exposure and circadian-system effects on dopamine rather than hypoxia itself, since both altitude and sunlight independently track with ADHD prevalence in US state-level data.[34] Both explanations converge on dopamine as the operative variable; which environmental lever moves it is unresolved.

Green outdoor play

[edit]

A national survey of 421 children with ADHD found those who regularly played in green outdoor settings had milder symptoms than children who played in built outdoor or indoor settings, across all income groups and both sexes; for children with the hyperactive subtype specifically, the benefit only showed up in relatively open green settings, not enclosed ones.[35]

Histamine and allergies (hypothesis)

[edit]

Overlap between ADHD-like symptoms and allergic or "allergic tension-fatigue" presentations has been discussed for decades. Histamine signaling and possible DAO deficiency may link ADHD and allergies; this is a hypothesis awaiting empirical tests, not an established link.[36] See Histamine.

Sleep and circadian phase

[edit]

Circadian rhythm dysfunction is clinically significant and highly prevalent in a substantial ADHD subgroup, with strong associations to evening chronotype and phase-delayed biological markers.[37] Insomnia and sleep disturbances affect up to about 80% of adults with ADHD and up to about 82% of children; delayed sleep-wake timing occurs in up to about 78%; dim-light melatonin onset (DLMO) is delayed by about 45 minutes in children and about 90 minutes in adults.[37] These alterations coincide with blunted and delayed cortisol rhythms, reduced pineal volume, and attenuated peripheral clock-gene rhythms (BMAL1/PER2).[37] Melatonin and bright light therapy advanced DLMO in children and adults with ADHD; emerging data correlate phase advancement with ADHD symptom improvement, and winter trials suggest circadian preference shifts best predict symptom improvement.[37] Behavioral sleep programs improve ADHD symptoms, sleep quality, and functioning in children.[37] See Sleep, Melatonin, Circadian rhythm.

Gut microbiota

[edit]

In a mouse study, germ-free male mice were colonized with pooled stool from three men with ADHD or three healthy men. Mice given the ADHD microbiota had lower white- and gray-matter structural integrity on diffusion tensor imaging (internal capsule, hippocampus), weaker resting-state connectivity between the right motor and right visual cortex, and more anxiety in the open-field test. They were not hyperactive: locomotion, marble burying and object recognition did not differ significantly.[38]

One man in an uncontrolled bipolar II FMT case report rated his ADHD symptoms as far less intense after FMT and doubted he still met ADHD criteria. This is one patient's self-report inside a bipolar case study. See Bipolar disorder#Faecal microbiota transplantation.[39]

Practice

[edit]

Serum ferritin was lower in ADHD than in controls in a meta-analysis. Serum iron itself did not differ from controls.[40] In a Paris clinic sample, children with ADHD had about half the mean ferritin of controls. Most of the ADHD group had ferritin under 30 ng/mL. Lower ferritin tracked worse Conners parent scores and greater cognitive deficits.[41] Iron is a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis.

Children with ADHD have measurably lower serum vitamin D than healthy controls, and within the ADHD group lower vitamin D tracked with more severe symptoms; vitamin D is a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, offering one plausible mechanism for the association.[42]

Children with ADHD had lower blood zinc than controls across case-control studies; zinc trials in children gave mixed results.[43] See Zinc#ADHD. In a six-week pilot trial without a placebo group, saffron capsules (20–30 mg a day) improved ADHD rating scores in children with no significant difference from a standard stimulant drug.[44] In a similar trial, ginkgo improved scores less than the same stimulant drug.[45]

Young adults with ADHD had lower blood riboflavin and vitamin B6 than controls, and lower levels of both tracked more severe symptoms.[46] In an open study without a placebo group, magnesium plus vitamin B6 for two months reduced hyperactivity in children with ADHD, and symptoms returned within weeks of stopping.[47]

Frontal lobes short of energy lose the capacity to inhibit distraction. Sleep, sugar stability, thyroid function, and light exposure raise that supply more sustainably than a stimulant alone. A thyroid check is reasonable after amphetamine treatment: growth stunting marks a hormonal cost, and correcting thyroid status may help recover physical and mental growth. Medical diagnosis remains necessary; this is not a substitute for it. See Sleep, Sugar, Thyroid, Light, Adrenaline, Dopamine.

Methylphenidate

[edit]

Methylphenidate (Ritalin) has been prescribed since the 1960s for hyperactive children, on the premise that it has a calming, focus-improving "paradoxical" effect on people who are supposedly already overstimulated. There is nothing physiologically paradoxical about it: the frontal lobes, the brain's most highly evolved and energy-demanding region, need a high, steady energy supply to sustain planning and prolonged attention; when that supply is inadequate, people and animals become hyperactive and unable to concentrate. Methylphenidate and caffeine both temporarily raise the brain's energy level, which is why either can make anyone, not just people diagnosed with a disorder, more focused.[48]

Function/Mechanism of action

[edit]

Adequate thyroid hormone is what keeps the brain's energy level high on its own; when thyroid function is deficient, the nervous system needs external stimulants to function normally, and the body compensates by producing large amounts of adrenalin instead.[48] Conditions that impair the brain's oxygen metabolism produce the attention-deficit phenotype directly; several studies found that coffee improved focus and attention not only in people with an ADD/ADHD diagnosis but also in honors students without one, indicating the effect is about brain energy supply in general rather than a disorder-specific drug action.[49]

Medical uses/Effects

[edit]

Risks

[edit]

As far back as the late 1960s, researchers were noticing a connection between amphetamines and lymphoma; Peat remained aware of the research for decades after a close friend who used Benzedrine regularly died of lymphoma in his 40s. For a long time few researchers would acknowledge the connection, but it is increasingly understood as a consequence of the toxic, chronic stress these stimulants place on the body rather than a direct carcinogenic action.[49] Raising adrenaline/sympathetic tone doesn't just act on the brain; it stresses the whole body, since these substances aren't simple "brain-active" drugs isolated from the rest of physiology.[50] Chronic amphetamine addiction, in particular, produces serious brain damage, likely including brain shrinkage. The brain functions as an interlocking system in which any sustained disruption forces a global, stressful readjustment rather than a change confined to one function.[50]

Methylphenidate is somewhat less addictive than methamphetamine, partly because of its longer half-life and partly because the oral route (as prescribed) doesn't produce the intense rush of other routes; this deterrent is incomplete, since crushing and insufflating (or, historically, injecting) the drug bypasses it. Sweden withdrew methylphenidate from its market in 1968 after a wave of abuse via non-oral routes, before it was reapproved for pediatric ADHD treatment decades later.[50][51]

Prescribed stimulants raise cardiovascular readings. In short-term randomized trials (median 7 weeks), amphetamines, lisdexamfetamine, and methylphenidate raised blood pressure and pulse against placebo; in adults, systolic increases ranged from 1.66 to 2.3 mm Hg, with very low certainty of evidence.[52] A meta-analysis of observational studies found no statistically significant association between ADHD medication use and cardiovascular disease.[53]

In healthy adults working a hard planning puzzle, methylphenidate, dextroamphetamine and modafinil raised effort but lowered the quality of solutions, and strong performers often slid below average.[54] College students who took stimulants without a prescription gained no grade advantage over their peers.[55]

Alternatives

[edit]

Because the underlying issue is brain energy supply, addressing thyroid function directly, improving diet (including keeping high-sugar foods away from children, since these interact with the same stress/energy systems), and supporting carbon dioxide production help restore normal attention and calm nerves by restoring their energy supply, rather than only masking the symptom with a stimulant.[49] Coffee itself, in normal dietary amounts, produces a comparable focus-improving effect through the same brain-energy mechanism, with a much better-established long-term safety profile.[48]

References

[edit]
  1. ↑ 1.0 1.1 Ray Peat, Nutrition for Women (book), "Diet Pills" section.
  2. ↑ Peat, Raymond. "Insomnia and Hyperactivity." Newsletter.
  3. ↑ 3.0 3.1 3.2 3.3 Peat, Raymond. Ray Peat, "Nutrition for Women", p. 72(Hyperactivity section)
  4. ↑ Ray Peat, "Nutrition for Women", p. 89(Diet Pills section)
  5. ↑ Caballero M, Núñez F, Ahern S, Cuffí ML, Carbonell L, Sánchez S, Fernández-Dueñas V, Ciruela F. "Caffeine improves attention deficit in neonatal 6-OHDA lesioned rats, an animal model of attention deficit hyperactivity disorder (ADHD)." Neuroscience Letters (2011). Caffeine improves attention deficit in neonatal 6-OHDA lesioned rats, an animal model of attention deficit hyperactivity disorder (ADHD)
  6. ↑ Pandolfo P, Machado NJ, Köfalvi A, Takahashi RN, Cunha RA. "Caffeine regulates frontocorticostriatal dopamine transporter density and improves attention and cognitive deficits in an animal model of attention deficit hyperactivity disorder," Eur Neuropsychopharmacol. 2013;23(4):317-328. PMID 22561003.
  7. ↑ 7.0 7.1 Alvarez-Pedrerol M, Ribas-Fitó N, Torrent M, Julvez J, Ferrer C, Sunyer J. "TSH concentration within the normal range is associated with cognitive function and ADHD symptoms in healthy preschoolers." Clinical Endocrinology (2007). TSH concentration within the normal range is associated with cognitive function and ADHD symptoms in healthy preschoolers
  8. ↑ Elshorbagy HH, Barseem NF, Abdelghani WE, Suliman HAI, Al-Shokary AH, Abdulsamea SE, Elsadek AE, Abdel Maksoud YH, Nour El Din DMAEH. "Impact of Vitamin D Supplementation on Attention-Deficit Hyperactivity Disorder in Children." Annals of Pharmacotherapy 52(7) (2018): 623-631. Impact of Vitamin D Supplementation on Attention-Deficit Hyperactivity Disorder in Children
  9. ↑ 9.0 9.1 Ray Peat, "Ray Peat in "A Questionable Remedy" (2010) about psychiatric drugs", YouTube
  10. ↑ Ray Peat, "Ask the Herb Doctor: Medical Misinformation", Ask the Herb Doctor
  11. ↑ Ask the Herb Doctor: Medical Misinformation, KMUD, 2018-10-19
  12. ↑ 12.0 12.1 Peat, Raymond. "Insomnia and Hyperactivity." Newsletter.
  13. ↑ Ray Peat, "Nutrition for Women", p. 73(Hyperactivity section)
  14. ↑ Brucker-Davis F, Skarulis MC, Grace MB, Benichou J, Hauser P, Wiggs E, Weintraub BD. "Genetic and clinical features of 42 kindreds with resistance to thyroid hormone. The National Institutes of Health Prospective Study." Annals of Internal Medicine 123(8) (1995): 572-583. Genetic and clinical features of 42 kindreds with resistance to thyroid hormone. The National Institutes of Health Prospective Study
  15. ↑ Weiss RE, Stein MA, Refetoff S. "Behavioral effects of liothyronine (L-T3) in children with attention deficit hyperactivity disorder in the presence and absence of resistance to thyroid hormone." Thyroid 7(3) (1997): 389-393. Behavioral effects of liothyronine (L-T3) in children with attention deficit hyperactivity disorder in the presence and absence of resistance to thyroid hormone
  16. ↑ Thyroid 7(3) (1997): 389-393
  17. ↑ Ookubo M, Sadamatsu M, Yoshimura A, et al. "Aberrant Monoaminergic System in Thyroid Hormone Receptor-β Deficient Mice as a Model of Attention-Deficit/Hyperactivity Disorder," Int J Neuropsychopharmacol. 2015;18(7):pyv004. PMID 25612897.
  18. ↑ Zametkin AJ, Nordahl TE, Gross M, King AC, Semple WE, Rumsey J, Hamburger S, Cohen RM. "Cerebral glucose metabolism in adults with hyperactivity of childhood onset." New England Journal of Medicine 323(20) (1990): 1361-1366. Cerebral glucose metabolism in adults with hyperactivity of childhood onset
  19. ↑ 19.0 19.1 Jahagirdar V, McNay EC. "Thyroid hormone's role in regulating brain glucose metabolism and potentially modulating hippocampal cognitive processes." Metabolic Brain Disease 27(2) (2012): 101-111. Thyroid hormone's role in regulating brain glucose metabolism and potentially modulating hippocampal cognitive processes
  20. ↑ Zametkin AJ, Liebenauer LL, Fitzgerald GA, et al. "Brain metabolism in teenagers with attention-deficit hyperactivity disorder," Arch Gen Psychiatry. 1993;50(5):333-340. doi:10.1001/archpsyc.1993.01820170011002. PMID 8489322. Case-control PET study, 10 adolescents with ADHD and 10 controls during an auditory-attention task; global metabolism not significantly different; normalized metabolism lower in 6 of 60 regions (P < .05); left anterior frontal metabolism inversely correlated with symptom severity (r = -.56 to -.67).
  21. ↑ Wu SQ, Feng F, Zou RJ, Fu HL, Sun JW, Jia XZ, Yin YF, Wang H. "Abnormal Brain Glucose Metabolism in Papillary Thyroid Cancer Patients 4 Weeks After Withdrawal of Levothyroxine: A Cross-Sectional Study Using 18F-FDG PET/CT." Frontiers in Endocrinology 12 (2021): 595933. PMC
  22. ↑ Yang MT, Lu DH, Chen JC, Fu WM. "Inhibition of hyperactivity and impulsivity by carbonic anhydrase inhibitors in spontaneously hypertensive rats, an animal model of ADHD," Psychopharmacology (Berl). 2015;232(20):3763-3772. doi:10.1007/s00213-015-4036-5.
  23. ↑ Edden RAE, Crocetti D, Zhu H, Gilbert DL, Mostofsky SH. "Reduced GABA concentration in attention-deficit/hyperactivity disorder," Arch Gen Psychiatry. 2012;69(7):750-753. PMID 22752239.
  24. ↑ Klocke B, Krone K, Tornes J, Moore C, Ott H, Pitychoutis PM. "Insights into the role of intracellular calcium signaling in the neurobiology of neurodevelopmental disorders," Front Neurosci. 2023;17:1093099. PMID 36875674.
  25. ↑ Þorsteinsson H, Baukmann HA, Sveinsdóttir HS, et al. "Validation of L-type calcium channel blocker amlodipine as a novel ADHD treatment through cross-species analysis, drug-target Mendelian randomization, and clinical evidence from medical records," Neuropsychopharmacology. 2025;50(7):1145-1155. doi:10.1038/s41386-025-02062-x. PMID 39953207. PMC12089589.
  26. ↑ Sawano E, Takahashi M, Negishi T, Tashiro T. "Thyroid hormone-dependent development of the GABAergic pre- and post-synaptic components in the rat hippocampus," Int J Dev Neurosci. 2013;31(8):751-761. PMID 24076339.
  27. ↑ Chen VC, Hsu TC, Chen LJ, et al. "Effects of taurine on resting-state fMRI activity in spontaneously hypertensive rats," PLoS One. 2017;12(7):e0181122. PMID 28700674.
  28. ↑ Chen VC, Chiu CC, Chen LJ, et al. "Effects of taurine on striatal dopamine transporter expression and dopamine uptake in SHR rats," Behav Brain Res. 2018;348:219-226. PMID 29694913.
  29. ↑ Rotem RS, Chodick G, Shalev V, et al. "Maternal Thyroid Disorders and Risk of Autism Spectrum Disorder in Progeny," Epidemiology. 2020. PMID 32251066. Cohort of over 437,000 singleton births; adjusted OR 1.26.
  30. ↑ McIlvride S, Rao N, Singh S, Nelson SM, Pell JP, Fleming M. "Prenatal exposure to maternal depression and antidepressants and neurodevelopmental outcomes: A population cohort study," PLoS Med. 2026;23(9):e1004658. doi:10.1371/journal.pmed.1004658. PMID 42809515. PMCID PMC13623103. Observational cohort, 132,779 children with full primary care coverage. ADHD: antidepressant exposure adjusted HR 1.89 (95% CI 1.57–2.27); untreated maternal depression adjusted HR 1.57. Predicted cumulative ADHD by age 12 per 100 children: 2.01 unexposed, 3.13 untreated depression, 3.66 treated depression, 3.73 antidepressants without recorded depression. Treated vs untreated depression difference 0.53 per 100 (95% CI −0.15 to 1.22), not significant.
  31. ↑ Volkow ND, Wang GJ, Kollins SH, et al. "Evaluating dopamine reward pathway in ADHD: clinical implications," JAMA. 2009;302(10):1084-1091. PMID 19738093. PET, 53 nonmedicated ADHD adults vs 44 controls. Binding potential, ADHD vs controls: accumbens DAT 0.63 vs 0.71 (95% CI of difference 0.03–0.13); midbrain DAT 0.09 vs 0.16; accumbens D2/D3 2.68 vs 2.85; midbrain D2/D3 0.18 vs 0.28.
  32. ↑ Volkow ND, Wang GJ, Newcorn JH, et al. "Motivation deficit in ADHD is associated with dysfunction of the dopamine reward pathway," Mol Psychiatry. 2011;16(11):1147-1154. PMID 20856250. MPQ Achievement 11±5 in ADHD vs 14±3 in controls.
  33. ↑ Huber RS, Kim TS, Kim N, Kuykendall MD, Sherwood SN, Renshaw PF, Kondo DG. "Association Between Altitude and Regional Variation of ADHD in Youth," J Atten Disord. 2018;22(14):1299-1306. PMID 25808310.
  34. ↑ Arns M, Swanson JM, Arnold LE. "ADHD Prevalence: Altitude or Sunlight? Better Understanding the Interrelations of Dopamine and the Circadian System," J Atten Disord. 2018;22(14):1409-1414. PMID 26341278.
  35. ↑ Faber Taylor A, Kuo FE. "Could Exposure to Everyday Green Spaces Help Treat ADHD? Evidence from Children's Play Settings," Appl Psychol Health Well Being. 2011;3(3):281-303. doi:10.1111/j.1758-0854.2011.01052.x.
  36. ↑ Blasco-Fontecilla H. "Is Histamine and Not Acetylcholine the Missing Link between ADHD and Allergies? Speer Allergic Tension Fatigue Syndrome Re-Visited," J Clin Med. 2023;12(16):5350. PMID 37629392. doi:10.3390/jcm12165350.
  37. ↑ 37.0 37.1 37.2 37.3 37.4 Luu B, Fabiano N. "ADHD as a circadian rhythm disorder: evidence and implications for chronotherapy," Front Psychiatry. 2025;16:1697900. PMID 41450833.
  38. ↑ Tengeler AC, Dam SA, Wiesmann M, et al. "Gut microbiota from persons with attention-deficit/hyperactivity disorder affects the brain in mice," Microbiome. 2020;8(1):44. doi:10.1186/s40168-020-00816-x. PMID 32238191. PMC7114819.
  39. ↑ Parker G, Spoelma MJ, Rhodes N. "Faecal microbiota transplantation for bipolar disorder: A detailed case study," Bipolar Disord. 2022;24(5):559-563. doi:10.1111/bdi.13187. PMID 35165993. PMC9545285.
  40. ↑ Wang Y, Huang L, Zhang L, Qu Y, Mu D. "Iron Status in Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis," PLoS One. 2017;12(1):e0169145. PMID 28046016. 10 studies, 1,196 ADHD cases; ferritin SMD −0.40 (95% CI −0.66 to −0.14); serum iron difference not significant.
  41. ↑ Konofal E, Lecendreux M, Arnulf I, Mouren MC. "Iron deficiency in children with attention-deficit/hyperactivity disorder," Arch Pediatr Adolesc Med. 2004;158(12):1113-1115. PMID 15583094. Mean ferritin 23±13 ng/mL in ADHD vs 44±22 in controls (P < 0.001); ferritin under 30 ng/mL in 84% of the ADHD group.
  42. ↑ Li HH, Yue XJ, Wang CX, Feng JY, et al. "Serum Levels of Vitamin A and Vitamin D and Their Association With Symptoms in Children With Attention Deficit Hyperactivity Disorder," Front Psychiatry. 2020;11:599958. doi:10.3389/fpsyt.2020.599958. PMID 33329153.
  43. ↑ Wang W, Tian L, Xu H, Zhou J, Geng M. "Essential Trace Elements Zinc, Iron, Copper and Attention-Deficit/Hyperactivity Disorder in Children and Adolescents: A Systematic Review and Meta-Analysis of Case-Control Studies," Nutrients. 2026;18(11):1797. doi:10.3390/nu18111797. PMID 42280439. Meta-analysis of 46 case-control studies; zinc SMD −1.01 (95% CI −1.51 to −0.52), high heterogeneity. An earlier meta-analysis of serum zinc found no significant overall difference: Ghoreishy SM et al., Sci Rep. 2021;11:14612. doi:10.1038/s41598-021-94124-5. PMID 34272450.
  44. ↑ Baziar S, Aqamolaei A, Khadem E, et al. "Crocus sativus L. Versus Methylphenidate in Treatment of Children with Attention-Deficit/Hyperactivity Disorder: A Randomized, Double-Blind Pilot Study," J Child Adolesc Psychopharmacol. 2019;29(3):205-212. doi:10.1089/cap.2018.0146. PMID 30741567. Six-week pilot RCT, 54 children; no placebo arm.
  45. ↑ Salehi B, Imani R, Mohammadi MR, et al. "Ginkgo biloba for attention-deficit/hyperactivity disorder in children and adolescents: a double blind, randomized controlled trial," Prog Neuropsychopharmacol Biol Psychiatry. 2010;34(1):76-80. doi:10.1016/j.pnpbp.2009.09.026. PMID 19815048. Six-week RCT, 50 children.
  46. ↑ Landaas ET, Aarsland TI, Ulvik A, Halmøy A, Ueland PM, Haavik J. "Vitamin levels in adults with ADHD," BJPsych Open. 2016;2(6):377-384. doi:10.1192/bjpo.bp.116.003491. PMID 27990293. Case-control study, 133 patients and 131 controls aged 18-40.
  47. ↑ Mousain-Bosc M, Roche M, Polge A, Pradal-Prat D, Rapin J, Bali JP. "Improvement of neurobehavioral disorders in children supplemented with magnesium-vitamin B6. I. Attention deficit hyperactivity disorders," Magnes Res. 2006;19(1):46-52. PMID 16846100. Open study, 40 children with ADHD and 36 controls; no placebo arm.
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  51. ↑ Singh I. "Ritalin at 75: what does the future hold?," The Conversation, 2019.
  52. ↑ Farhat LC, et al. "Comparative cardiovascular safety of medications for attention-deficit hyperactivity disorder in children, adolescents, and adults: a systematic review and network meta-analysis", Lancet Psychiatry. 2025. PMID 40203844.
  53. ↑ Zhang L, et al. "Risk of Cardiovascular Diseases Associated With Medications Used in Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-analysis", JAMA Netw Open. 2022. PMID 36416824. 19 studies, about 3.9 million participants; stimulants RR 1.24 (95% CI 0.84–1.83).
  54. ↑ Bowman E et al. 2023. "Not so smart? Smart drugs increase the level but decrease the quality of cognitive effort", Sci Adv. 2023;9(24):eadd4165. PMID 37315143. Knapsack task vs placebo; value attained fell, decision time and steps rose.
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