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As with all risk factors, these do not cause ADHD: they add an element of risk and may act in synergy with other risk factors or susceptibility genes. Their risk promoting ability may be increased or decreased by these other factors.

Genes, environmental risk factors and medical conditions associated with Attention deficit hyperactivity disorder (ADHD)

Ongoing clinical trails, worldwide, can be interrogated at ClinicalTrials.Gov a service of the US National Institutes of Health

Search MedlinePlus:
  • ADHD societies UK USA Europe
  • ADDIS ADHD information services (UK)


Netdoctor ADHD

Hyperactive children's support group (UK)

OMIM Online Mendelian Inheritance in Man, a database of human genes and genetic disorders developed by staff at Johns Hopkins University






Risk Factor (Links to Wikipedia and Pubmed)

Genes associated with ADHD KEGG pathway analysis of ADHD genes See also ADHDGene from CAS for genes and pathway enrichment

Genome wide association: See:- Genome.gov and HuGE navigator


Pre- and non-GWAS Copy number variations / deletions are highlighted in bold

Infectious agents PANDAS (Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus) Refs


  • Association with allergic rhinitis Suwan et al, 2011 and other atopic diseases (asthma, eczema ) Schmitt et al, 2013
  • A higher frequency of food allergies is observed in ADHD Almog et al, 2010
  • Early food allergy and respiratory allergy symptoms independently and synergistically contribute to higher risk of ADHD Jiang et al, 2018.
  • Thimerosal-containing vaccines (organic mercury) have been linked with a number of neurodevelopmental disorders including ADHD and autism Young et al, 2008
  • Increasing organic-Hg exposure from Thimerosal-containing vaccines heightens the risk of a "Hyperkinetic syndrome of childhood" diagnosis Geier et al, 2016.
  • Association between atopic dermatitis and ADHD in children and adults Strom et al, 2016

Prenatal factors and Birth related

  • ADHD risk has been reported to be increased in children born to women experiencing a viral rash during pregnancy (measles, varicella or rubella) Arpino et al, 2005.
  • Premature delivery symptoms, severe flu attacks and neonatal seizures have been asociated with the subsequent development of ADHD Pineda et al, 2003
  • The use of acetaminopen during pregnancy has been linked to the subsequent development of ADHD Liew et al, 2014 see also Bauer et al, 2018
  • Low maternal folate has been associated with ADHD Schlotz et al, 2010
  • High intrauterine testosterone may be associated with ADHD James, 2008
  • Prenatal alcohol exposure has been associated with ADHD Pineda et al, 2007 Toxicity of alcohol or acetaldehyde may be involved in relation to uterine exposure Abel, 1984
  • Prenatal methamphetamine exposure has been associated with ADHD LaGasse at al, 2012 and prenatal cocaine exposure has been associated with subsequent behavioural problems Levine et al, 2012
  • Association with pre-eclampsia Mann and McDermott, 2010
  • Gestational diabetes has been associated with the later development of ADHD in the offspring Nomura et al, 2011
  • Febrile seizures have been associated with ADHD Pineda et al, 2010
  • a relation between passive smoking and behavioural disorders including attention deficit/hyperactivity disorder (ADHD) has been reported Hofnuis et al, 2002
  • Prenatal tobacco use has been associated with ADHD Braun et al, 2006
  • Young maternal age and birthplace has been associated with ADHD, which predominantly affects males
  • Severe hyperbilirubinemia at birth has been associated wit\h later development of autism and to a lesser extent, ADHD Jangaard et al, 2008
  • Children exposed to anaesthesia more than twice before the age of 3 are twice as likely to have ADHD than children who have not been exposed. Sprung et al, 2012
  • Maternal thyroid peroxidase autoantibodies have been associated with ADHD related problems in the children Ghassabian et al, 2012
  • Children exposed to maternal hypothyroxinemia in early pregnancy had more ADHD symptoms Modesto et al, 2015
  • Maternal hyperthyroidism diagnosed and treated for the first time after the birth of the child increased the risk of ADHD in the child Andersen et al, 2014
  • ADHD risk in the offspring is associated with parental immune disorders (multiple sclerosis, rheumatoid arthritis, type 1 diabetes, asthma and hypothyroidism ) Instanes et al, 2015
  • Prenatal lead exposure (cord blood lead levels) has been associated with a 3.43 times higher risk for hyperactivity in both boys and girls: Prenatal p,p'-DDE (para,para dichlorodiphenyldichloroethylene ) levels increased total prolems in girls and emotional problems were associated with prenatal cadmium levels in boys Sioen et al, 2013
  • Smoking in pregnancy, maternal urinary tract infection, induction of labour, and experiencing threatened preterm labor increased the risk of ADHD, with little gender difference. Early term deliveries marginally increased the risk of ADHD.oxytocin augmentation of labor appears protective for girls Silva et al, 2013
  • Maternal stress during pregnancy, postpartum depression, and changes in the primary caretaker during first 3 years associated with ADHD Park et al, 2014
  • Higher maternal circulating levels of vitamin D (25-hydroxyvitamin D3) in pregnancy associated with lower risk of developing ADHD-like symptoms in childhood Morales et al, 2015.
  • Prenatal antidepressant use during pregnancy associated with the subsequent development of ADHD in the offspring Clements et al, 2015
  • Maternal chemical intolerance associated with ADHD and autism in the offspring Heilbrun et al, 2015
  • Birth month asociated with the incidence of ADHD (upward trend towards the later part of the year peaking in November: northern hemisphere) Boland et a, 2015
  • Maternal medium/high use of cell phones during pregnancy may be associated with an increased risk for behavioral problems, particularly hyperactivity/inattention problems, in the offspring Birks et al, 2017.
  • Maternal obesity before pregnancy is a risk factor for ADHD in children. Maternal obesity as well as underweight may also be associated with an increased risk for Autism spectrum disorders Andersen et al, 2017.


Dietary factors, environment, pollution and toxins
  • Increased blood concentrations of lead , manganese and zinc have been associated with ADHD Yousef et al, 2011 See also Bellinger 2011
  • Lead and polychlorinated biphenyls have been associated with ADHD Eubig et al, 2010
  • Polybrominated diphenyl ether flame retardant exposure has been associated with ADHD Sagiv et al, 2015
  • High cadmium exposure has been associated with ADHD, in those with higher lead levels Ciesielski et al, 2012
  • Manganese exposure has been asociated with ADHD Farias et al, 2010 Hong et al, 2014
  • High mercury levels have been associated with ADHD Cheuk and Wong 2006
  • Traffic pollution (elemental carbon attributed to traffic) during the child's first year of life was significantly associated with Hyperactivity T-scores at 7 years of age Newman et al, 2013
  • Lower zinc levels have been asociated with ADHD Oner et al, 2010
  • Iron deficiency has been associated with ADHD Calarge et al, 2010
    • Lower ferritin levels have also been associated Refs
  • Zinc deficiency has been associated with ADHD Dodig-Curkovic et al, 2010
  • Particulate pollution from motor vehicles has been associated with ADHD Siddique et al, 2010
  • Early-life exposure to air pollution from indoor gas appliances has been associated with ADHD Morales et al, 2009
  • Children with ADHD consumed half the amount of fish/seafood, meat and eggs when compared to the norm Nq et a, 2009
  • Fatty acid deficiency symptoms of dry hair and skin, frequent thirst and urination have been observed to be higher in children with attention deficit hyperactivity disorder Sinn, 2007
  • Food colorings, including tartrazine or carmoisine, Rowe 1988 and food additives (sodium benzoate) have been implicated in hyperactivity Connolly et al, 2010
  • The contentious colourings are: sunset yellow FCF (E110), quinoline yellow (E104), carmoisine (E122), allura red (E129), tartrazine (E102) and ponceau 4R (E124)) A Guide to E numbers
    • The effects of food additives are modified by HNMT polymorphisms, suggesting an effect related to histamine Stevenson et al, 2010
    • Those affected by food additives may also be sensitive to common nonsalicylate foods (milk, chocolate, soy, eggs, wheat, corn, legumes) as well as salicylate-containing grapes, tomatoes, and oranges Stevens et al, 2011.
  • Trichlorophenols (organochlorine compounds in pesticides) have been linked to ADHD Xu et al, 2011 Organochlorines Sagiv et al, 2012
  • Pyrethroid pesticide use linked to ADHD (stronger in boys -` `urinary levels of pyrethroid metabolite 3-phenoxybenzoic acid) Wagner-Schuman et al, 2015
  • Prenatal exposure to polycyclic aromatic hydrocarbons (air pollutants from fossil fuel burning and other combustion sources) has been associated with attention deficits Perera et al, 2012 and 2018
  • Hexachlorobenzene has been associated with ADHD Ribas-Fitó et al, 2007
  • Exposure to organophosphate pesticides has been associated with ADHD Marks et al, 2010
  • dimethylphosphate (organophosphate metabolite) urinary levels asociated with ADHD Yu et al, 2016
  • Prenatal chlorpyrifos levels have been associated with ADHD Rauh et al, 2006
  • Exposure to Phthalates has been associated with ADHD Jurewicz and Hanke, 2011
  • Iatrogenic exposure to di(2-ethylhexyl)phthalate metabolites during intensive care (circulating phthalates leaching from indwelling medical devices) associated with the important attention deficit observed in children 4 years after critical illness Verstraete et al, 2016
  • Polyfluoroalkyl chemical exposure has been linked to ADHD Hoffmann et al, 2010
  • Exposure to polybromodiphenyl ethers used as flame retardants has been linked to ADHD Gascon et al, 2011
  • Prenatal or childhood exposure to Bisphenol A has been associated with ADHD Mustieles et al, 2015
  • High serum serum concentrations of persistent organic pollutants belonging to the categories of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans have been associated with ADHD Lee et al, 2007
  • Higher reports of ADHD symptomatology in areas supplied with fluoridated water Malin and Till, 2015
  • omega-3 and omega-6 fatty acids as well as magnesium and zinc have been reported to improve symptoms Huss et al, 2010
  • Some ADHD children are sensitive to common nonsalicylate foods (milk, chocolate, soy, eggs, wheat, corn, legumes) as well as salicylate-containing grapes, tomatoes, and orange Stevens et al, 2011.
  • The ScanBrit study has reported significant improvement with gluten and casein free diets in autism spectrum disorders, including ADHD Whiteley et al, 2010
  • There is a lower prevalence of ADHD in areas with high solar intensity ( not found for the prevalence of autism spectrum disorders or major depressive disorder) Arns et al, 2013
  • A traditional-healthy dietary pattern associated with lower odds having ADHD and a snack pattern with higher odds Woo et al, 2014.
  • Energy drinks associated with attention/hyperactivity problems in youth Schwartz et al, 2015
  • Sugar sweetened beverages associated with ADHD Yu et al, 2016
  • Maternal Licorice Consumption During Pregnancy associated with an increased risk of ADHD in children: Girls and boys exposed to high maternal glycyrrhizin consumption scored lower on tests of intelligence quotient, had poorer memory , and had 3.3-fold higher odds of ADHD problems compared with children whose mothers consumed little to no glycyrrhizinRäikkönen et al, 2017
  • Increased mean platelet volume has been observed in ADHD children.Yorbik et al, 2014


Drugs and treatments Association with other diseases and conditions Others
  • Gene expression studies in ADHD brains converge on immune related pathways , oxidative stress and mitochondrial pathways Lintas et al, 2010
  • Low levels of 3-hydroxykynurenine have been reported Oades et al, 2010
  • Inattention may be greater in the evening and hyperactivity greater in the evening in males Bae et al, 2010
  • A lower ADHD prevalence has been found in regions of high solar intensity Arns et al, 2013

Plasma/serum levels

  • Lower plasma cortisol in ADHD Ma et al, 2011
  • Low plasma levels of phenylalanine, tyrosine, tryptophan, histidine, and isoleucine Bornstein et al, 1990
  • higher omega-3 levels polyunsaturated fatty acid levels were associated with decreased inattention, hyperactivity, emotional and conduct difficulties and increased levels of prosocial behaviour Kirby et al, 2010.
  • Increased plasma levels of BDNF Shim et al, 2008
  • Low levels of intact parathyroid hormone Humble et al, 2010
  • Increased levels of malondialdehde ( a marker of oxidative stress and lipid peroxidation) Bulut et al, 2007
  • ADHD is associated with increased antennary fucosylation of biantennary glycans and decreased levels of some complex glycans with three or four antennas.Pivac et al, 2011
  • Glutathione peroxidase activities of ADHD patients were significantly lower and catalase levels higher Ceylan et al, 2010
  • Lower levels of glutathione Dvoráková et al, 2006
  • Low levels of pregnelonone, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate are associated with hyperactivity Strous et al, 2001
  • total and HDL cholesterol levels were significantly increased in patients with low monoamine oxidase activity Kiive at al, 2005
  • Overall symptom ratings have been associated with increases of the interleukins IL16 and IL13, inveresly correlated with S100B levels: Increased response time variability has been related to lower TNF-alpha, and higher Interferon gamma levels Oades et al, 2010
  • Low serum levels of docasahexaenoic, dihomogammalinolenic, and arachidonic acids have been reported Mitchell et al, 1987 along with low plasma levels of alpha-linoleic acid and oleic acid Spahis et al, 2008
  • plasma gamma-linolenic acid in ADHD children was higher than that in controls . For phospholipids isolated from red blood cell membranes, oleic acid was significantly higher, whereas nervonic acid , linoleic acid , arachidonic acid , and docosahexaenoic acid were lower in subjects with ADHD Chen et al, 2004.
  • circulating levels of miRNA 18a-5p, 22-3p, 24-3p, 106b-5p and 107 levels significantly decreased in ADHD patients Kandemir et al, 2014

An article on the developmental toxicity of industrial chemicals Labie 2007

European Food safety authority

Pesticides and disease database including childhood developmental disorders

DEVNERTOX Toxic threats to the developing nervous system: in vivo and in vitro studies on the effects of mixture of neurotoxic substances potentially contaminating food

HAZMAP A Relational Database of Hazardous Chemicals and Occupational Diseases

IVTIP In vitro testing industrial platform

Toxics Release Inventory (TRI) Program : USA environmental protection agency

Dangerous household chemicals

TOXNET - Databases on toxicology, hazardous chemicals, environmental health, and toxic releases.

Adult ADHD test

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