Attention deficit hyperactivity disorder (ADHD) is now one of the most common childhood disorders and can continue into adulthood. Symptoms include difficulty staying focused and paying attention, difficulty controlling behavior, and over-activity.
According to the National Institutes of Health (NIH) the disorder can vary, causing some with it to be impulsive while others are mostly inattentive. Doctors are not sure what causes ADHD, although many studies suggest that genes play a large role.
A new study by neuroscientists at the Mayo Clinic in Florida and at Aarhus University in Denmark believe a contributing factor is a miswiring of neurons in the brain's reward system.
In their research they found a receptor system that ensures the brain neurons are wired correctly. They also found that cutting that system causes damage that results in typical ADHD symptoms.
“A number of studies have reported that ADHD patients commonly exhibit miswiring in this brain area, accompanied by altered dopaminergic function,” said Dr. Anders Nykjaer, the study's lead investigator. “We may now have an explanation as to why ADHD risk genes have been linked to regulation of neuronal growth.”
Nykjaer and his team say they are working on a therapy that prevents damage to this key brain circuit. It could be a big step since NIH says currently available treatments focus on symptoms and improving functioning. Treatments include medication, various types of psychotherapy, education or training, or a combination of treatments.
Other studies over the years have suggested other causes. Some researchers have found a link between smoking and alcohol use during pregnancy.
Others have linked the disorder to brain injuries. Some have even linked the severity of ADHD symptoms to refined sugar, though NIH notes more research discounts that theory than supports it.
When it comes to treating ADHD with drugs, some doctors are very concerned when the patient is a very young child. The Centers for Disease Control and Prevention (CDC) estimates 10,000 U.S. toddlers receive medication for ADHD symptoms.
"It does not surprise me that some children are being given medicine as the easy way out but that doesn't mean it's the right way to do it," said Dr. Max Wiznitzer, a pediatric neurologist at University Hospitals in Cleveland, Ohio.
But Wiznitzer doesn't rule out drug therapy either. He says the drugs Ritalin and Adderall have proven effective, but in patients who are at least 3 years-old.
"It's almost unheard of to give ADHD medication to a 2-year-old," Wiznitzer said.
The American Academy of Pediatrics has issued no guidelines for ADHD in children under the age of 4 but Wiznitzer says the Preschool ADHM Treatment Study, funded by the U.S. government, looked at ADHD in children as young as 4.
He says, while medication for toddlers shouldn't be ruled out, it should only be a last resort. And that means making certain that the symptoms are really stemming from the disorder and not something else.
“We've made sure they (the patients) do have ADHD features, that their behavior is occurring in multiple settings, that it's not due to poor parenting, it's not due to poor teaching, it's not some other medical condition," Wiznitzer said.