Researchers have long focused upon the problems of student/adolescent drug use; however, such a limited perspective may actually provide inaccurate information as to the actual nature and extent of total drug use. It may be more appropriate to emphasize a lifespan developmental perspective regarding drug abuse behaviors, insofar as drug use must be analyzed on a continuum during the lifetime of the individual, rather than as an isolated experience during a particular period of development. Analyzing drug abuse behaviors from such a developmental perspective includes six periods of development: the fetal period, infancy, childhood, adolescence, adulthood, and old age. Based upon joint considerations of developmental psychopharmacology and the biological boundaries of learning, an hypothesis of "developmental dependencies" may account for some of the interactions between drug abuse and the continually developing organism. (Author)