In his new book, "What Causes ADHD? Understanding What Goes Wrong and Why," Michigan State University psychologist Joel Nigg brings together the most recent neuropsychological research in an attempt to answer this challenging question.
"Essentially there are multiple causes," said Nigg. "Some we already know of, others have been suggested and disproved, still others deserve more study."
Nigg, an associate professor of psychology, said that while his book was written mainly for professionals and is a bit technical in places, parents longing for more ADHD information may find it useful, too.
"It's the kind of book that if you want to look something up, it has a specific section on those topics that we know about, such as television watching, diet and so on," he said.
In the United States, as many as 7 million children have been diagnosed with ADHD. The disorder is defined as a problem with inattentiveness, overactivity, impulsivity or a combination of those. For these problems to be diagnosed as ADHD, they must be out of the normal range for the child's age and development, and cause impairment in the child's life.
In addition to helping parents, the book could also be of assistance to health care professionals, many of whom are on the front lines of dealing with ADHD and may struggle to keep up with rapidly developing literature.
"If you're a professional, how do you answer questions from parents, many of whom know very little about scientific findings related to ADHD?" Nigg asked. "Hopefully this book can bring a broad range of data within easy reach of professionals who find it difficult to keep up with such huge literatures."
Nigg is a clinical psychologist who has worked with hundreds of children with ADHD and related conditions. He has trained numerous graduate students in the evaluation and assessment of ADHD in children, adolescents and adults. He also is an active scientist engaged in research on the condition.
His research has focused on neuropsychological markers of ADHD, genetics of ADHD, family processes, and, most recently, the potential ADHD-causing effects of environmental pollutants, including lead, cadmium and persistent organic pollutants such as PCBs.
"What Causes ADHD?" is his first book.
"There are so many things written about ADHD that are simplistic and brief, often because they are for a different purpose," he said. "I wanted to explain it with more detail and get everything in one place."