The Research Story

I began studying ADHD formally more than 20 years ago. During that time, I have also always had a clinic in which I would see kids and parents, usually for diagnostic evaluation when the situation was complex or unclear. Thus, I’ve been influenced both by my scientific experience and knowledge of the literature and by my encounters with hundreds of children and families and their very real dilemmas, struggles, pain, courage, persistence, determination—and their joys and love.

My scientific work has always reflected three interests: genetics, early experiences ranging from traumatic events to family supports, diet, and pollutants; and the biological layer of ADHD. My earlier work really was about trying to identify useful signals of ADHD in neuropsychological function, that might relate to genetic or family transmission. For example, in one well cited early paper we found that if a child with ADHD had difficulties in an ability called executive function, so did his or her parents—even if they did not have ADHD.

Evaluating the endophenotype model of ADHD neuropsychological deficit: results for parents and siblings of children with ADHD combined and inattentive subtypes.

While we added some genetic and inheritance studies (and are still doing that), our work also moved into a greater interest in the environment. One key pivot point for us was in 2006 when we published the first of a series of papers showing that lead exposure, even at the very low levels now typical in the United States and believed to be safe, in fact are correlated with ADHD.ADHD  boy reading a book laughing

Low Blood Lead Levels Associated with Clinically Diagnosed Attention-Deficit/Hyperactivity Disorder and Mediated by Weak Cognitive Control

Our most recent paper in this line used a novel genetic design to isolate the lead as a causal contributor. You can read that paper here

Variation in an Iron Metabolism Gene Moderates the Association Between Blood Lead Levels and Attention-Deficit/Hyperactivity Disorder in Children

In parallel, we started investigating other environmental claims. Food and nutrition was a very interesting one. I was asked to assist with a review of the role of artificial food coloring in ADHD. We conducted a very careful, systematic and statistical analysis of every study ever done on this topic. The results surprised me—we saw an effect in controlled experiments, both on symptoms rated by parents and on laboratory tests of attention. The effect wasn’t huge—but it confirmed that something is going on with food and ADHD.

Meta-Analysis of Attention-Deficit/Hyperactivity Disorder or Attention-Deficit/Hyperactivity Disorder Symptoms, Restriction Diet, and Synthetic Food Color Additives

We used the same approach to establish that ADHD is associated with reduced blood levels of omega-3 fatty acids—a “good fat” found in fish—and that supplementing the diet with these nutrients can partially relieve ADHD symptoms.

Omega—3 fatty acid and ADHD: Blood level analysis and meta-analytic extension of supplementation trials

In the meantime, we also contributed to the emerging clarity that aDHD is associated with socio-economic disadvantage—perhaps due to stress on the family, worse nutrition, or other factors. That work is forthcoming.

As I explain in the book the genetic and environment effects on ADHD can be combined into a sensible explanation of how ADHD happens, using the story of epigenetics—or how the environment can change genes.

I gradually developed a strong interest in helping parents get a handle on the new direction the science of ADHD is taking. Thus, my book, “Getting Ahead of ADHD” is an up to date summary of what we know in all areas of ADHD and the environment, including exercise, diet, video games, pollutants, and also answers common questions about different new treatments using technology as well as behavioral and medicine treatments and new diagnostic tools.

I hope you find it helpful!

No information on this site substitutes for professional medical advice. Dr. Nigg is unable to answer all questions submitted and will never give individual medical recommendations without a full evaluation.

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