Although the exact cause of ADHD remains unknown, research has increased in the last decade. At present, the most likely cause of ADHD is believed to be genetic, but other causes have been implicated as well.

Support for a Genetic Link

Research repeatedly demonstrates that ADHD runs in families. Recently published data in Pediatric Annals indicate that the child of an adult with ADHD has approximately a 25% chance of having ADHD. There are also indications that the type of ADHD that persists into adulthood is more highly genetic than the type that diminishes in childhood.

Although the cause of ADHD is unknown, some researchers believe it is due to many factors. In addition to genetic causes, there are other environmental and medical factors that can cause ADHD-like symptoms. Careful examination, however, reveals important differences between these disorders and ADHD. Overall studies have concluded that heredity explains, on average, the majority of ADHD-like behavior exhibited by children, while environmental factors explain only approximately 20% of this type of behavior.

Robert D. Hunt. An update on assessment and treatment of complex attention-deficit/hyperactivity disorder. Pediatric Annals March 2001; 30:(3) 163.

Unproven Causes

In the past, uncertainty about the causes of ADHD created a fertile climate for speculation of all kinds. Many theories – notably those holding parents to blame in some way for their child’s uncontrolled behavior – have been advanced and were later determined to be unfounded.

Among the most well-known include:

  • Food/diet
  • Poor parenting
  • Excessive television watching or video-game playing
  • Hormones

These factors were initially believed to be causes of ADHD because they appear to be connected. Parents claimed that when they fed their children sugar or various other foods, they became more hyperactive; certain diets claimed to eliminate hyperactivity. Professionals who witnessed uncontrolled behavior concluded that parenting methods must be flawed. Hyperactive children seemed to watch more TV and play more video games than other children. It seemed plausible that the emotion inherent in ADHD could stem from some kind of hormonal imbalance, much like the moodiness of adolescence.

However, carefully-designed, rigorous studies failed to find that any of these observed associations were causes of ADHD, nor could any of these factors modify the symptoms of ADHD. For example, contrary to parental beliefs, sugar did not make children significantly more hyperactive. No diet, in fact, was found to reduce ADHD symptoms. Parenting techniques did not improve symptoms; parental frustration was in fact found to be an effect, not a cause, of ADHD. Excessive television watching and video game playing also was determined to be a symptom, not a cause, of ADHD. It is a form of stimulation that helps children with the disorder sustain focus and control internal feelings of agitation.

It has become increasingly clear that ADHD is a neurological disorder that requires a medical diagnosis and treatment.