ADHD ADHD Guide ADHD Guide Symptoms Causes Diagnosis Treatment Living With In Children Causes and Risk Factors of Attention-Deficit Hyperactivity Disorder (ADHD) By Keath Low Keath Low Keath Low, MA, is a therapist and clinical scientist with the Carolina Institute for Developmental Disabilities at the University of North Carolina. She specializes in treatment of ADD/ADHD. Learn about our editorial process Updated on March 09, 2022 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Steven Gans, MD Medically reviewed by Steven Gans, MD Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital. Learn about our Medical Review Board Print Table of Contents View All Table of Contents Common Causes of ADHD Genetics Illnesses and Injuries Toxins Exposure to Substances in Utero Next in ADHD Guide Testing for ADHD Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral condition that causes symptoms of inattention, hyperactivity, and impulsivity. It is usually diagnosed during childhood, but it can also affect adults. The exact cause of ADHD isn't known. But researchers suspect there may be several factors that determine whether someone might develop ADHD. Genetics, toxins, exposure to substances during prenatal development, and certain medical conditions can all play a role. This article explores the different causes of attention-deficit hyperactivity disorder. Verywell / Brianna Gilmartin Common Causes of ADHD Researchers believe that there are many different causes of ADHD. Some of the factors that can contribute or increase the risk of developing ADHD include: GeneticsExposure to environmental toxinsExposure to substances in uteroIllness and injuryPremature birth What Does Not Cause ADHD Researchers have also discovered which factors don't play a role in causing ADHD. Watching TV, diet (including too much sugar), hormone disorders, poor parenting, and playing video games do not lead to ADHD. Genetics Whether you have recently been diagnosed with ADHD or have been living with ADHD for many years, a question almost all adults ask is: "Will my children have ADHD, too?" The answer is: It depends. ADHD is primarily a hereditary disorder. It is estimated that the percentage of genetic contribution to ADHD is over 70%. Despite this strong genetic link, having ADHD doesn’t automatically mean you'll pass it on to your child. This is because it is a combination of genes and environmental factors that determine whether a child develops ADHD. Children can inherit ADHD genes without them being activated. For example, one research study found that only one-third of fathers with ADHD had children that also developed ADHD. If a child inherits ADHD from a parent, the parent's ADHD presentation or subtype (inattentive, hyperactive-impulsive or combined) will not influence the ADHD presentation of the child. To date, several gene candidates have been found in families who demonstrate ADHD. However, scientists feel that it is not one particular gene but the interaction of several of these genes and the environment that cause ADHD symptoms to manifest. ADHD is not a sex-linked condition. In other words, ADHD does not occur only in males and is thus not passed down only from a father to the children. Some people think, “It’s only fathers who can have ADHD, and if the dad doesn’t have ADHD then the child can’t possibly have it.” This is inaccurate. Although ADHD is diagnosed more frequently in males than females, it is important to understand that people of all genders can have ADHD. Illnesses and Injuries Illnesses such as meningitis or encephalitis can result in learning and attention problems. A small percentage of people experience ADHD symptoms as a result of brain damage, such as an early brain injury, trauma, or another impediment to normal brain development. One study published in JAMA Pediatrics found that children with a history of traumatic brain injuries, even if less severe, have an increased risk of developing ADHD for as long as 10 years after the injury. Toxins Being exposed to certain environmental toxins during childhood can increase the risk that a child will develop ADHD. Exposure to lead (even low levels) can result in hyperactivity and inattention. Lead can be found a variety of places, such as in the paint of homes built before 1978 or previously in gasoline. Exposure to Substances in Utero A gestational parent's health and habits during pregnancy can also play a role in the development of ADHD. Poor nutrition and infections during pregnancy can increase the risk of ADHD, for example. There's also evidence that using some substances during pregnancy increases the risk that the child will develop ADHD. Smoking A 2018 study published in Pediatrics found a significant relationship between smoking during pregnancy and the likelihood of a child having ADHD. The risk of ADHD was greater in children whose mothers smoked heavily. The study couldn't conclude that smoking causes ADHD, but it did indicate that a correlation exists. Alcohol Some studies have found that parents who drink during pregnancy are more likely to have children with ADHD. A 2018 study found that consuming four or more drinks at a time, or regular low to moderate alcohol, use was associated with a significant increase in the chances that a child would later have ADHD. A 2017 study, however, found that there was no link between maternal alcohol use and a clinical ADHD diagnosis in children. This study suggested that children may develop some symptoms of ADHD if their parent used alcohol during pregnancy, but they didn't necessarily qualify for an ADHD diagnosis. 10 Risks of Smoking During Pregnancy Summary It's likely that ADHD stems from a variety of causes. Someone who has a genetic predisposition, for example, may encounter environmental factors that also contribute to the development of ADHD. Toxins, exposure to substances during prenatal development, certain types of infections, and brain injuries can increase the risk that a person will develop ADHD. A Word From Verywell Researchers continue to learn more about the potential causes and risk factors for ADHD. While the exact causes may not be known, it is important to know that there are effective treatments available that can help you or your child manage the symptoms of the condition. Talk to your healthcare provider if you think you or your child may have ADHD to learn more about what treatment options might work best for you. How Is ADHD Diagnosed? 12 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Franke B, Faraone SV, Asherson P, et al. The genetics of attention deficit/hyperactivity disorder in adults, a review. Mol Psychiatry. 2012;17(10):960-87. doi:10.1038/mp.2011.138 National Institutes of Health. The ADHD Genetic Research Study. Starck M, Grünwald J, Schlarb AA. Occurrence of ADHD in parents of ADHD children in a clinical sample. Neuropsychiatr Dis Treat. 2016;12:581-8. doi:10.2147/NDT.S100238 Hadzic E, Sinanovic O, Memisevic H. Is bacterial meningitis a risk factor for developing attention deficit hyperactivity disorder. Isr J Psychiatry Relat Sci. 2017;54(2):54-57. Chou IC, Lin CC, Kao CH. Enterovirus encephalitis increases the risk of attention deficit hyperactivity disorder: A Taiwanese population-based case-control study. Medicine (Baltimore). 2015;94(16):e707. doi:10.1097/MD.0000000000000707 Adeyemo BO, Biederman J, Zafonte R, et al. Mild traumatic brain injury and ADHD: a systematic review of the literature and meta-analysis. J Atten Disord. 2014;18(7):576-84. doi:10.1177/1087054714543371 Narad ME, Kennelly M, Zhang N, et al. Secondary attention-deficit/hyperactivity disorder in children and adolescents 5 to 10 years after traumatic brain injury. JAMA Pediatr. 2018;172(5):437. doi:10.1001/jamapediatrics.2017.5746 Donzelli G, Carducci A, Llopis-gonzalez A, et al. The association between lead and attention-deficit/hyperactivity disorder: A systematic review. Int J Environ Res Public Health. 2019;16(3) doi:10.3390/ijerph16030382 Huang L, Wang Y, Zhang L, et al. Maternal smoking and attention-deficit/hyperactivity disorder in offspring: a meta-analysis. Pediatrics. 2018;141(1):e20172465. doi:10.1542/peds.2017-2465 Pagnin D, Zamboni Grecco ML, Furtado EF. Prenatal alcohol use as a risk for attention-deficit/hyperactivity disorder. Eur Arch Psychiatry Clin Neurosci. 2019;269(6):681-687. doi:10.1007/s00406-018-0946-7 Eilertsen EM, Gjerde LC, Reichborn-Kjennerud T, et al. Maternal alcohol use during pregnancy and offspring attention-deficit hyperactivity disorder (ADHD): a prospective sibling control study. Int J Epidemiol. 2017;46(5):1633-1640. doi:10.1093/ije/dyx067 Dark C, Homman-ludiye J, Bryson-richardson RJ. The role of ADHD associated genes in neurodevelopment. Dev Biol. 2018;438(2):69-83. doi:10.1016/j.ydbio.2018.03.023 By Keath Low Keath Low, MA, is a therapist and clinical scientist with the Carolina Institute for Developmental Disabilities at the University of North Carolina. She specializes in treatment of ADD/ADHD. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit Speak to a Therapist for ADHD Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.