About this Research Topic
The number of people abusing methamphetamine (MA) is increasing. MA has short- and long-term effects on brain development and functioning. The risk of the developing brain being exposed to MA is high since most MA-using women are of childbearing age and MA use increases the likelihood of engaging in risky sexual behavior. Maternal MA use is associated with increased risk of preterm birth, complications associated with hypertension, placental abruption, and physical abnormalities at birth, as well as cognitive impairments, including hippocampus-dependent cognitive impairments, in childhood. These effects, as well as short- and long-term effects of MA exposure in adulthood might involve the brain’s reward circuitry, the stress axis, and changes in circadian rhythms. Pre-existing genetic risk factors are likely involved as well. Chronic MA exposure in adult rodents has acute effects on the length of the free-running period and duration of activity in rats and mice. The MA dose, time of day, and interval between MA administrations, all modulate the direction of these effects. Following MA abstinence, there are behavioral alterations and increased psychotic symptoms, including increased social anxiety and depression. For example, adolescents in treatment for MA abuse show higher levels of depressive symptoms and suicide ideation than adolescents being treated for other abused substances. MA exposure early on in life, including in utero exposure, and exposure during adolescence might be particularly problematic. In rodents, adolescent animals self-administer MA at a significantly higher rate and show enhanced sensitivity to the rewarding properties of MA than adult. However, other studies suggest the adolescent brain might be partially protected from the effects of MA on locomotor activity and on reductions in dopamine transporter (DAT) or tyrosine hydroxylase activity. Clearly more research is needed. This Frontiers Research Topic aims to serve as a host for studies describing the short- and long-term effects of MA exposure in humans and animal and cellular models and in particular the physiological and molecular mechanisms that might be involved in these effects.
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