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ADHD May Be Caused By A Glitch In The Internal Timing Of The Brain

Professor David Gilden

Professor David Gilden

Susan, even at age 33, cannot sit still. She never could. Pegged by her teachers as the resident “problem child,” she spent most of her afternoons in detention for disrupting class and forgetting her homework assignments. As an adult, she still struggles to meet her work deadlines, and she has to fight the insatiable urge to dart out of meetings.

“Just the thought of sitting through a meeting or going to the movies makes me feel anxious,” says Susan, who asked to be identified by her first name only, in fear of being stigmatized by Attention Deficit Hyperactivity Disorder (ADHD). “My mind is bouncing around like a ping-pong ball and I can’t focus on one thing for longer than a few minutes.”

Susan is among the estimated 5 percent of American adults who, according to the National Institute of Mental Health, are living with ADHD, a neurobiological condition marked by impulsive behavior and a lack of focus.

University of Texas at Austin psychologist David Gilden’s research findings suggest the underlying problem doctors have diagnosing ADHD may be in recognizing that it is not an issue of attention, but rather a problem of timing. According to his research, people with ADHD have a much quicker sense of the here and now, such as the moment it takes to thread together two sentences in a classroom lecture. This timing glitch often causes them to fall out of sync with the rest of the world.

Once diagnosed, the symptoms of ADHD are often managed with stimulant medication, but according to Gilden, to effectively treat the disorder clinicians need to have a clear understanding of the underlying deficit.

“The first thing in any treatment is understanding what it is that’s being treated,” Gilden says. “At this time, that’s missing. People have been focusing on ADHD as if it’s an attention disorder, but I don’t think that’s what it is.”

Using drums, Legos, puzzles and Play-Doh, Gilden and his team of researchers are searching for the root cause of ADHD. By allowing their study participants to tinker with the toys in an unconstrained environment, the researchers are able to track timing differences in their natural behaviors.

“ADHD is not about inattention,” Gilden says. “It’s a disorder in the way people thread moment-to-moment experiences together. Children with ADHD are often disruptive because their world is moving at a much faster pace and there’s always going to be a mismatch between their world and ours.”

As part of his research, Gilden measured how people with and without the disorder tap along to the beat of a metronome. The respondents then continue tapping at the same pace for three minutes after the metronome stops. Although both groups were able to tap to the beat at 60 beats per minute, the participants with ADHD lost the rhythm when the tempo slowed down to 40 beats per minute.

“The slower the tempo, the more likely people with ADHD will be less internally consistent with themselves,” Gilden says. “It’s not that they’re inattentive, it’s just that their world is moving along at a slightly faster clip.”

To measure the timing disruptions, Gilden and his team videotaped the hand movements of more than 60 undergraduate students as they worked on various projects like piecing together a puzzle, building Lego structures or molding Play-Doh.

After conducting a frame-by-frame analysis of the action sequences of each hand movement (such as touching a puzzle piece and fitting two pieces together) the researchers found significant differences in timing between ADHD and non-ADHD participants.

Although both groups used similar action sequences and constructed their Lego and Play-Doh projects in the same order, the participants with ADHD took about one-third of a second longer carrying out a task like fitting two Lego pieces together.

“One-third of a second seems like a short amount of time, but in psychophysics, this is a huge timing difference because it only takes the average person one-tenth of a second to initiate an action,” Gilden says. “This is a very puzzling discovery because although their minds are moving at a faster rate, they’re actions are more spacious.”

Sifting Through the Noise
While all the participants moved freely during the study, Gilden, who holds a doctorate in astronomy, found a hidden structure in the patterns of their actions. He found each moment-to-moment fluctuation in hand movements resembles 1/f noise (pronounced one over F), which is not an audible noise, but a mysterious wave-like pattern that appears in natural and unnatural surroundings. Investigated by scientists for more than a century, the noise has yet to be explained.

Gilden is the first to show that 1/f exists in human consciousness. In a 1995 study published in Science, he found that all humans produce the noise. However, his recent studies have shown that the noise is much harder to detect in people with ADHD, as their movements are more erratic.

From fluctuating weather patterns, to the beating of a heart, to pitch and loudness in music and speech, our world is full of 1/f noise. To illustrate this highly complex concept, Gilden plays a piano rendition of Summer Samba. In between the fluctuating tempos and repetitive melodies, he explains how the patterns in music achieve 1/f noise.

“When you listen to this song, you’ll find that it follows a formula of repetition and surprise folded into a pattern of organization,” Gilden says. “Music is the blend between the ordered states and disordered states, and that’s exactly what 1/f achieves.”

legos in the adhd sutyd

To measure cognitive timing differences between people with and without ADHD, Gilden and his team of researchers analyze their hand movements as they build Lego structures in an unconstrained environment. (click to enlarge)

Pointing to a video of a student assembling Legos, Gilden illustrates the alternating patterns in each movement. With each action unit (such as a touch, pause or fitting of two Lego pieces) the student produces a train of durations that resemble 1/f noise.

Using Gilden’s research, James Cutting, professor of psychology at Cornell University, studies how editing techniques in filmmaking follow the pattern of human attention. In a recent study, he found the basic shot structure and scene clusters in movies have evolved over the years to resemble the pattern of 1/f noise.

By timing the scenes just right, moviemakers can capture the viewers’ attention without overly taxing their attention span, Cutting says. If the audience hears something the brain doesn’t recognize as the correct sequence – such as quick zooms and pans – they’re unable to make the connections and their minds wander.

Gilden’s research shows compelling evidence that people think, focus and refocus their minds, all at the speed of 1/f, Cutting says.

“When you’re working on a task, sometimes you’re good at it, sometimes you drag and sometimes you zone out,” Cutting says. “We experience these periods of fluctuation throughout our daily lives. And each of these fluctuations creates waves that essentially form a 1/f pattern.”

By applying this theory to ADHD research, Cutting says Gilden is on the right track to understanding the underlying deficit.

Understanding Attention
More than 5.4 million children in the United States have been diagnosed with ADHD according to the Centers for Disease Control. And as that number continues to grow, Gilden says researchers and clinicians need to find out if the disorder has anything to do with attention.

“What is attention? It’s such an abstract concept,” Gilden says. “Attention involves focusing and letting go at the same time, but other than that – I’m not sure what it is.”

This has made treating the disorder particularly difficult. After being diagnosed with ADHD, people are often prescribed psychotropic drugs that come with an array of side effects like mood swings and loss of appetite. The problem with this method, Gilden says, is that clinicians are treating a condition that they do not fully understand.

Without a clear understanding of attention, psychologists have made very little progress in identifying cognitive deficits in ADHD, Gilden says.

“You can’t find a cure until you understand the underlying problem,” he says. “If a doctor suspects you have the flu, he can prescribe a drug specifically targeted for that virus. But when psychologists diagnose people with ADHD, they need to understand what the deficit is before prescribing a full spectrum of treatment that has nothing to do with the condition.”

To seek out the underlying deficit, he examines the disorder from an entirely new perspective by applying an anthropological approach to his research.

“The problem with most ADHD research involving time-pressured experimental trials is that people with the disorder tend to be more erratic,” Gilden says. “We’re interested in the natural flow of behavior. Instead of giving them time-pressured tasks, we allow them to generate their own thoughts and actions.”

Diagnosing a Growing Epidemic
So what is behind the rise in ADHD diagnoses? That is the question plaguing millions of parents every year. Is it a biological illness, environmental toxins or a mere alibi for rambunctious children?

Despite decades of research, the underlying problem still remains unclear. However, recent mounting evidence in brain studies has shown that the deficit is caused by a stunted dopamine system, the brain’s reward pathway that associates stimuli with pleasurable expectations.


Using Play-Doh, the researchers examine how people with ADHD move to the beat of a faster cognitive tempo. Over time, Gilden aims to create diagnostic tools using drumming, Play-Doh and other methods to replace current diagnostic tests, which he believes are ineffective.

“Our research is motivated by studies that show abnormalities in specific areas in the brain,” Gilden says. “There are parts of the ADHD brain that are affected and dopamine pathways are altered. We’re studying how blunted dopamine signals create problems with timing.”

Since dopamine is also involved in memory, learning and motivation, the chemical helps people pay attention to the information they need to survive. However, those with ADHD might not be recognizing salient information due to an impaired dopamine system, Gilden says.

In a current study, funded by the National Science Foundation, Gilden and his team are examining how the effects of dopamine dysfunction play into the production of 1/f noise. They found that when participants with ADHD are thrust into a stress-induced environment involving time-pressured tasks, their behavior resembles the kind of noise that a radio makes when not tuned to a station – what scientists call a white noise.

This finding suggests that situations like structured classroom activities, final exams and prolonged meetings are not conducive to people with ADHD. Gilden says researchers, parents and teachers need to take a step back and look for new ways to help people with the disorder adjust to the world around them.

“Our research is motivated by the idea that there is something deeply wrong with the accepted view of ADHD and how people with ADHD are understood,” Gilden says.

The harmful effects of ADHD sometimes persist into adulthood, and many adults who have it do not know it. As a result, they fail to seek treatment and continue to struggle at work or in school and in their personal relationships.

Over time Gilden hopes to create a diagnostic tool using drumming and other methods to replace other diagnostic tests, which he says are ineffective.

Professor David Gilden and his graduate research assistants

Professor David Gilden and his graduate research assistants, Maryam Ezell (left) and Laura Marusich, examine frame-by-frame hand movements in videos to measure cognitive timing differences between people with and without Attention Deficit Hyperactivity Disorder. (click to enlarge)

“ADHD has massive consequences for adult function,” Gilden says. “People with ADHD are more likely to get into car accidents, be admitted to emergency rooms, and are more likely to be divorced. Perhaps these problems could be prevented if the disorder is accurately diagnosed early on.”

Caryn Carlson, professor of psychology and assistant chair of the Psychology Department at the university, says findings from Gilden’s research could help teachers capture their students’ attention through strategically timed lectures and classroom activities.

“There is typically a mismatch between the demands of the classroom environment and the attention style of children with ADHD,” Carlson says. “This may be characterized by an inability to focus during extended desk work sessions, missing task instructions due to distractibility and making careless errors.”

Carlson cites other research findings that show the consequences of untreated ADHD, even after children are finished with school, can have a profound impact on their lives.

“When children fail to master critical early academic skills, the effects on school performance can become cumulative and result in failure, frustration and demoralization,” Carlson says.

Looking back, Susan says she wishes her teachers developed classroom activities that were more conducive to students like herself who were chronically bored and restless.

“Back then, I was all over the place,” Susan says. “I couldn’t handle the structure and the teachers didn’t know what to do with me. For the longest time, I thought something was very wrong with me, which is why I have such poor self-esteem. If I was diagnosed early on – who knows – I may have achieved my goal of becoming a history professor.”

Watch A Related News Video–ut-researchers-study-adhd-diagnosis

Original article by Jessica Sinn at University of Texas.

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5 Responses to ADHD May Be Caused By A Glitch In The Internal Timing Of The Brain

  1. avatar
    Christopher Fisher, PhD September 18, 2011 at 10:06 AM #

    This is a very interesting line of research. The concept of 1/f noise is discussed in the book Neurofeedback and State Regulation in ADHD: A Therapy Without Medication by Werner Van den Bergh, M.D., here:

    There are objective and reliable measures of ADHD, such as the TOVA test. But this is a very interesting and novel approach to the assessment of this disorder. As a neurofeedback clinician, it also raises interesting possibilities of the treatment of ADHD. We already know that neurofeedback is a highly effective treatment of ADHD. It may be that neurofeedback alters the timing of neural events rather than the amplitudes of specific frequencies. Clinicians can be objectively investigate this further with QEEGs administered pre-post treatment.

  2. avatar
    Jennifer October 18, 2011 at 10:16 AM #

    This is the theory on which Brain Balance has based it’s intervention for years now. The founders of Brain Balance contend that de-synchronization between and within the two hemispheres of the brain causes ADHD symptoms and that improving that communication will decrease symptoms. You can read about it on their website.

  3. avatar
    steve July 25, 2012 at 1:56 PM #

    Found this fascinating, Chris. The literature suggests a strong positive correlation between intelligence and ADHD. I come from a school of thought that intelligence is largely about processing speed and this would seem to fit what the authors are talking about. The TOVA becomes a good test because it is so severly out of sync with those with ADHD that they really stick out in the results.

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