Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder characterized by symptoms like impulsiveness in behavior, hyperactivity, and inattentiveness. ADHD hinders the process by which a person’s brain processes information.
Mostly, ADHD is diagnosed in childhood and often lasts into adulthood. The exact cause of ADHD is still unknown but researchers believe that factors like genetics, nutrition, central nervous system problems during development, and several other factors may have a role to play in the development of this disorder.
What Causes Attention Deficit Hyperactivity Disorder (ADHD)?
Till now there is no exact known cause of attention deficit hyperactivity disorder (ADHD) but scientists are studying the causes and risk factors so that they can find better ways to manage the symptoms and reduce the chances of a person developing ADHD.
Researchers suggest that genetics and environmental factors have an essential role to play in the development of ADHD. Besides, there are some other factors that may be responsible which include the following:
- Brain injury
- Consuming tobacco and alcohol during pregnancy
- Premature births
- Exposure to environmental contaminants during pregnancy
- Low birth weight
Role of Genetics in Attention Deficit Hyperactivity Disorder (ADHD)
Researches strongly suggest that genetics is involved in the development of ADHD. It is suggested that ADHD runs in families who have some genetic history of this disorder, however, the exact gene responsible for this disorder is yet to be discovered. There has been found twofold to eightfold increased risk of ADHD in people with some family history of ADHD compared to relatives of unaffected controls.
Monozygotic twins have much higher rates of ADHD compared to dizygotic twin pairs. Several chromosomal abnormalities like an abnormality in the number of chromosomes especially sex chromosomes have been linked to the development of attention deficit hyperactivity disorder.
Besides, some abnormalities in the structure of chromosomes and some single-gene disorders have also been found to be associated with the development of ADHD. Some disorders may be associated with the ADHD. These include Fragile X syndrome, tuberous sclerosis, Smith Magenis, and Velocardiofacial syndromes.
Brain Injury and ADHD
According to experts, any kind of injury to the brain may cause ADHD symptoms, probably due to damage to the frontal lobe of the brain which is responsible for controlling the feelings and emotions. Brain injuries may be caused due to any physical injury either before or after the birth or due to exposure to toxins.
Consuming Tobacco and Alcohol During Pregnancy
Prenatal exposure to alcohol and smoking has been associated with the behaviors of children with ADHD. Studies suggest that children who have undergone prenatal exposure to alcohol and drugs are more likely to develop ADHD.
Premature Births and Low Birth Weight
Studies suggest that some children are at a higher risk of developing ADHD especially the ones who are born with low birth weight or born prematurely. Also, children born to mothers who had a difficult pregnancy are also at a higher risk of getting ADHD.
Exposure to Environmental Contaminants During Pregnancy
Exposure to environmental toxins like lead may cause behavioral problems in children both before and after birth.
What Does NOT Cause Attention Deficit Hyperactivity Disorder (ADHD)?
There are many myths and misconceptions about ADHD. Following are some of the myths which have no role to play in the development of ADHD according to the researchers:
- Playing video games
- Excess consumption of sugar
- Watching television
- Poor parenting
Risk Factors for Attention Deficit Hyperactivity Disorder (ADHD)
Risk factors increase the chances of developing a disease or a disorder. ADHD can develop without risk factors as well but the more risk factors a person has, the greater is his or her chances of developing the disorder. Following are some of the common risk factors of ADHD:
Boys are more frequently diagnosed with ADHD compared to girls.
The symptoms of ADHD often appear in childhood.
Environmental Toxins and Premature Births
Children who are born prematurely are at a high risk of developing ADHD. Also, children exposed to some environmental toxins like lead (found in pipes and paint in old buildings) have greater chances of developing ADHD.
Children born to parents having alcohol use disorder or conversion disorder are at a greater risk of developing ADHD.
Many ADHD symptoms may be hereditary. Some studies have suggested that genes are responsible for causing ADHD in children. ADHD has been found to be highly genetic.
According to a study by Morrison and Stewart (1971), it was found that 20% of ADHD children had an ADHD parent compared to only 2% of normal controls. The study also revealed that parents of ADHD children had a higher prevalence of alcoholism, hysteria, and sociopathy compared to parents of normal controls.
Traumatic Brain Injury
In some children, brain injury can be linked to ADHD, however the number is very small.
According to some International studies, following socioeconomic factors may play a role in the development of ADHD:
- History of paternal antisocial behavior
- Maternal depression
- Uneducated mother
- Early childhood trauma
- Maternal complications during pregnancy
- Paternal criminality
- Maternal mental disorders
- Marital conflicts like separation and divorce
- Early life deprivation which may be involved in disrupted cortical development that ultimately reduces cortical thickness and atypical functioning in regions involved in the regulation of attention
- Maternal chemical intolerance