Georgetown College. Georgetown University.

Attention Deficit and Hyperactivity Disorder (ADHD) currently affects a considerable 5 percent of American school-age children. As a result, there has been an increased incentive in the last 10 years for research on the neurobiology of ADHD, prompted by the National Institutes of Health (NIH). Autism has also recently seen a surge in diagnoses and been conspicuous in news and research. Autism is a perplexing condition that yields mild to severe attention dysfunctions in certain abilities (particularly those affecting social functioning), alongside sometimes incredible skill and capacity for focused attention in other situations. Both conditions affect children from an early age; ADHD diagnosis is most reliable after age 7 years while Autism is typically diagnosed much earlier on. Both conditions manifest themselves in varying degrees of attention dysfunction, distractibility, and impulsivity.

Dr. Chandan Vaidya, Georgetown Assistant Professor of Psychology, and her students in the Developmental Cognitive Neuroscience Lab (DCNL) have targeted a key process of self-regulation in the brain that is affected by both of these conditions called executive control, which mediates one’s ability to focus in spite of potential distractions. Executive control is a crucial functioning aspect of our brains that enables us to consciously learn, focus, and study, as well as to behave in ways that are appropriate to our context or setting.

Dr. Vaidya describes problems with executive control in ADHD and Autism as a symptom of neurobiological dysfunction, much in the way that a fever is a symptom sickness in the body. Children with ADHD manifest problems with executive control in their high levels of distractibility and impulsive behaviors. Children with Autism can also behave impulsively, and exhibit characteristics of being both hyperfocused and distractible, with social settings often exacerbating these problems for them.

Dr. Vaidya and her students approach their study of these dysfunctions by directly looking at the brain activity of children who are affected, using a state-of-the-art functional Magnetic Resonance Imaging (fMRI) machine. The fMRI allows them to perform noninvasive brain imaging (without exposure to radiation) on children engaging in certain tasks that target impulsivity, distractibility, and executive control.

For their studies, Dr. Vaidya and her students measure brain activity in a control group of children who are not affected by ADHD or Autism, but who have the same IQ and similar backgrounds/lifestyles to the children affected by ADHD and Autism. The children lie still in the fMRI, with their head enclosed by a helmet-like headset that allows for projection of a computer screen on which cognitive tasks are presented that the children respond to by pushing buttons with their hands, much like in a behavioral laboratory setting.

A task that tracks impulsivity is one where the child is told to press a button (the same button) for each letter of the alphabet that appears, except for the letter “x,” which occurs rarely (e.g., 12% of the time). This sort of task is called a “go/no go” task and taps into a child’s ability to inhibit a response rather than acting impulsively. Other tasks that more specifically target the child’s ability to be distracted will display the word “left” or “right” together with the icon of an arrow that does not always point in the direction indicated by the word. The child is asked only to pay attention to the verbal prompt, and control of distractibility is measured by the child’s ability to respond accurately to the verbal prompt even when the icon is contradictory. An additional task that is used for autistic children to track their responsiveness to social information modifies the above example with the use of a generic face with the eyes looking either to the right or to the left. Eyes are a powerful mode of communicating social information, and therefore, are distracting when gaze direction contradicts the word. Findings have confirmed that autistic children are less distracted by information conveyed by eye gaze.

In children with ADHD, the fMRI is also used in learning how or why a particular drug therapy works. Since the fMRI enables Dr. Vaidya and her students to see which regions of the brain are active, monitoring the same child with and without the effective drug therapy allows them to see which regions of the brain mediate the positive changes. The medication could be stimulating the very regions that were documented as underactive, but it could just as well be stimulating and introducing other regions of the brain to mediate the activity. They are able to perform these studies with children with ADHD who are being successfully treated with Ritalin because Ritalin peaks in two hours, so they can compare test results at the peak of its effectiveness to results when the Ritalin is no longer in the child’s system. Dr. Vaidya and her students have found that Ritalin improves the activity in the prefrontal cortex and basal ganglia regions of the frontal cortex of the brain, which are regions that are underactive in children with ADHD.

Such research will also be effective in potentially eliminating much of the trial and error frequently involved in finding the right treatment for children, since a relationship can be established between the level of activity or inactivity in certain parts of the child’s brain and the type and dosage of drug needed. More complicated, and thus trickier to treat, Autism does not currently lend itself to drug therapy that could be evaluated in the way that Dr. Vaidya and her students look at the actions of Ritalin in children with ADHD.

Dr. Vaidya is very excited about bringing genotype information into the study of ADHD. “Looking at polymorphisms of genes that code for neurotransmitter functions such as dopamine, which is affected in ADHD, will help us to predict earlier who might be at risk for ADHD,” she says. Using genotype information and brain imaging together promises to enable potent and efficient advances in diagnostics and treatment of ADHD and related illnesses.

The neurobiology of ADHD and Autism is complex and will take time to fully understand. When confronted with the question of whether these illnesses are a product of modern times or strictly psychiatric conditions, says Dr. Vaidya, the answer is always both—dynamically both, because criteria for diagnosis includes how maladaptive the child’s behavior is. As such, gaining a grasp of the neurobiological end of the equation is an important step in understanding and treating ADHD and Autism.

Dr. Vaidya has undergraduate students involved every step of the way at the DCNL, from screening children and parents to performing behavioral tests to analyzing data. Undergraduates are generally assigned to a project led by a graduate or post-doctoral student who serves as their mentor. Interest has recently surged and this semester she has five undergraduates working in her lab, as opposed to a usual two to three students in past semesters. Her students are all very motivated and high achieving, with many of them being awarded summer GUROP fellowships.

While Dr. Vaidya and her students have predominantly focused on the attentional dysfunction (pertaining to executive control) aspects of Autism in the DCN lab, graduate student Kelly Barnes has been looking at implicit learning in Autistic children in a related project, in collaboration with Dr. Darlene Howard, whose Cognitive Aging Lab does extensive work with implicit learning. Learn more about Dr. Howard’s work with implicit learning.

Since trials and equipment are expensive (the fMRI costs $500 per hour of use!), outside funding is important. Dr. Vaidya’s lab currently receives funding from NIH and Autism Speaks for their research. The lab also receives support in the form of pre-doctoral training grants for students.

In addition to her work in the lab, Dr. Vaidya teaches Cognitive Neuroscience for undergraduates, a graduate seminar in Cognitive Neuroscience, and a Research Methods and Stats class.

Dr. Vaidya is well-loved and appreciated by her students. “I could not have had a better mentor as an undergraduate. Dr. Vaidya embodies professionalism and integrity,” says Lauren Kaplan. Michael Billington adds: “She is a very intelligent and compassionate woman who cares deeply both for her research and for her graduate and undergraduate students. She always has time to talk when I have questions about what we’re doing and even when I just want to see what she thinks about something new I’ve read or learned in another class. She’s a very good teacher and scientist, and I’m very happy to be working for her.”

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