2002 NARSAD Distinguished Investigator Grantee Joseph Biederman, M.D., collaborated in a study that may help to explain the dramatic spike, estimated at up to 40 percent, in the occurrence of attention-deficit hyperactivity disorder (ADHD) in children born in recent decades. The study’s findings, reported on February 19th in The Journal of Neuroscience, suggest that the increase may be the result of having grandmothers who smoked while pregnant, irrespective of whether or not the grandmothers’ daughters—the children’s mothers—smoked.
The research reinforces other recent discoveries showing that changes to the genome can be induced by environmental factors, such as stress or drug use, or in this case nicotine, and that these changes may be permanent and transmissible across generations, even skipping generations. While the study was conducted with laboratory mice, a demographic clue seems to support possible extrapolation of its finding to human illness. Previous studies have demonstrated a correlation between smoking and ADHD, but smoking rates were declining in the U.S. at the time ADHD rates were rising. However, many young women had begun to smoke in the years around and after World War II.
The study was conducted by a team of researchers from Florida State University College of Medicine, and Massachusetts General Hospital, where Dr. Biederman is Director of Pediatric Psychopharmacology. The challenge now, the researchers explain, is to discover the mechanisms that underlie how transmission of genome changes to future generations occurs, and, ultimately, how detrimental changes can be corrected to avoid future transmission.