Neurodevelopment and Drugs

Neurodevelopment is a continuous, complex, and strictly regulated biological process that begins early after conception during embryonic life and continues into young adulthood. However, fetal brain development during gestation is a window of high vulnerability. Diverse coordinated biological processes occur during this critical period including neurulation, neurogenesis, microglial entry, synaptogenesis and pruning, programmed cell death, and myelination. Disturbances to these processes can produce short- or long-term detrimental effects on brain development. These include chronic forms of congenital malformations or long-term postnatal neurodevelopmental disorders. Congenital malformations include neural tube defects (NTDs) in which the development of the brain or the spinal cord structure is impaired. These malformations can be fatal. Moreover, impairment in biological processes can lead to a wide range of long-term functional disorders called neurodevelopmental disorders. These are a group of disorders characterized by impairments in developmental domains including cognition, communication, behavior, or motor skills. Genetic factors or environmental exposures during gestation have been linked with neurodevelopmental deficits. In this chapter, cellular and molecular pathways of neurogenesis are described in addition to characterizations of NTDs and postnatal neurodevelopmental disorders. Finally, an update on neurodevelopmental outcomes of prenatal exposure to drugs of abuse, prescribed medications, or environmental factors is provided.