Effects of ethanol and nicotine on human CNS development

Publisher Summary This chapter discusses the effects of nicotine and ethanol during central nervous system (CNS) development. It is worth mentioning that both substances might interfere with fertility. Disorders related to maternal ethanol drinking are categorized as fetal alcohol spectrum disorders. The most common neurophysiologic alterations related to FAS/FASD include difficulties with arithmetic and number processing, verbal and non-verbal learning, speech and language delay, attention deficits and altered executive functions. Maternal smoking is related with a wide range of alterations, such as low weight at birth, high rates of sudden infant death syndrome and neuropsychological disturbances, mainly somatosensory deficits, difficulties in learning, high rates of attention deficit hyperactivity disorder, aggressive and antisocial behavior and anxiety. Once absorbed, ethanol is distributed in all tissues in proportion to their water content; the highest concentrations of ethanol are found in the blood and brain, followed by muscles and fat tissue. Smoked nicotine is absorbed mainly in the lungs, but also in the mouth; it is then quickly distributed throughout the organism, mainly in the liver, brain, kidneys and spleen. There is a great amount of evidence of the toxicity of ethanol during brain development; in fact, maternal ethanol consumption during pregnancy is considered one of the main causes of impaired cognitive functions and mental retardation. It is accepted that nicotine might play a neuroprotective role in adults, while its presence in developmental periods is linked to neurotoxicity, interfering in brain development in a dose-dependent manner. Adolescents, who consume ethanol present alterations in learning and memory, which are related with reduced blood oxygen levels in brain areas. Adolescents seem less sensitive to the adverse effects of tobacco than adults.