Mood Disorders

Relating the biochemical changes accompanying physical development at puberty with a child’s emotions, communication difficulties, and behavior is obviously a challenge. The contribution by Vigil and colleagues (“Endocrine Modulation of the Adolescent Brain”) in this issue of the journal reviews some of the countless studies and clinical observations used to bridge this gap. The authors have lined up a selection of suspect proteins and steroids that may modify the adolescent brain, affect moods, and alter behavior. It is obvious that the pharmacology of mood chemistry is alive and well. However, it is unlikely that there will ever be a scientific tool to estimate the degrees of neural plasticity necessary to process information appropriately and negotiate this challenging period of life. As Peter Medawar once stated, “it may be more difficult than we can think.” Yet we cannot help asking, as the authors of this excellent review have done, “What genes, pathways, and their mutations impair this plasticity and set the stage for variant behavior? Are these mutations germ line or conceivably somatic in origin? Can they account for all changes in behavior? What percentage of the phenotype is accounted for by genetic susceptibility loci?” Perhaps it is time for developmental neuroscientists and behavioral geneticists to answer these questions together. The molecular genetics are challenging, since these behavior traits are most likely to be a multilocus model with several levels of interaction.