The ADHD rats couldn’t control themselves. They kept pressing the button as if in an automatic frenzy, invariably checking to see if it had worked. After a while, the ordinary rats had realized their reward for pressing the button would only be forthcoming after a short delay. So they stopped. But the ADHD rats could not stop. And as Dr Vivienne Russell will tell you, people with ADHD are just like those rats.
The ADHD rats couldn’t control themselves. They kept pressing the button as if in an automatic frenzy, invariably checking to see if it had worked. After a while, the ordinary rats had realized their reward for pressing the button would only be forthcoming after a short delay. So they stopped. But the ADHD rats could not stop. And as Dr Vivienne Russell will tell you, people with ADHD are just like those rats.
“It’s as though they’re not learning from their mistakes,” she says, and her audience is disturbed.
That’s because many of them either have ADHD (Attention Deficit Hyperactivity Disorder) or know someone who has it, and Dr Vivienne Russell from Department of Human Biology at UCT was speaking at Think!Fest about the latest research on the brains of the frenzied rats. The experiment in question was recently repeated with children in Norway who could not stop either.
“I’ve seen a child with white knuckles hanging on to the cupboard saying I CAN’T WAIT,” recalls Russell of the disorder, and the audience murmurs appreciatively.
It not a coincidence that the lack of control sounds like addiction; ADHD is affected by the activity of the same neurotransmitter – dopamine – that abuse of drugs like cocaine, ecstasy, caffeine etc modify in the brain.
For people with ADHD there is evidence that “the dopamine system has been changed… but we do not know exactly what [the alteration]is.”
What we do know is that ADHD brains do not develop efficient neural networks and do not mature like ordinary brains do. For the 5-10% of people of people all over the world who develop this disorder that translates into inattention, hyperactivity and impulsivity, which means, basically, “They are risk takers.”
“We’re cannon fodder,” grins a member of the audience, responding to Russell’s assertion that society benefits from these risk-taking strategies.
There’s also evidence that people with ADHD “can certainly adapt and be very creative,” says Russell;
“[It’s] a strong characteristic of those [with the disorder].”
But implementing that creativity in a sustained productive manner is not so easy, since new research indicates that those with ADHD “just don’t have the same drive.” This, the rats could not have taught us.
“Ten years ago we depended completely on animal studies to understand the human brain,” mentions Russell, “but we can now also measure parts of the brain in living human beings with having to take out a piece of the brain.”
MRI (Magnetic Resonance Imaging) allows us to see into our living tissues from the outside, and they showed recently that the ventral striatum was smaller, particularly on the right side, in those with ADHD. The ventral striatum includes the nucleus accumbens, which maintains levels of motivation when a person starts a task and continues to maintain motivation until the task is completed, meaning that people with ADHD often suffer from an “inability to allocate sufficient effort.”
Meaning that they would probably stopped reading after the word “frenzied rats.”
Yet technically, it’s proving a massive effort for science to discriminate between people who have ADHD, and those who are just plain naughty.
“We’re not close at all to having a definitive test,” says Russell. “The diagnosis is inconsistent to say the least.”
That may be problematic, since research Russell has been hesitant to publish indicated that although ADHD rats that had been treated from a young age with Ritalin showed a decreased preference for cocaine, ordinary ones who went through the same process demonstrated an increased preference for cocaine in adulthood.
And Ritalin, despite being widely prescribed for the treatment of ADHD, is not the wonder-drug everyone was hoping for: “The disappointment in the field is that methylphenidate [Ritalin] is not a cure,” says Russell. For a disorder that has been debated to be one of epidemic proportions, researchers like Russell may still be having their buttons pushed for years to come by ADHD’s legions of rats, people and plain naughty kids.
