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Our aim is to present a working model that may serve as a valuable heuristic to predict enduring effects of drugs when administered during development. Our primary tenet is that a greater understanding of neurodevelopment can lead to improved treatment that intervenes early in the progression of a given disorder and prevents symptoms from manifesting. The immature brain undergoes significant changes during the transitions between childhood, adolescence, and adulthood. Such changes in innervation, neurotransmitter levels, and their respective signaling mechanisms have profound and observable changes on typical behavior, but also increase vulnerability to psychiatric disorders when the maturational process goes awry. Given the remarkable plasticity of the immature brain to adapt to its external milieu, preventive interventions may be possible. We intend for this review to initiate a discussion of how currently used psychotropic agents can influence brain development. Drug exposure during sensitive periods may have beneficial long-term effects, but harmful delayed consequences may be possible as well. Regardless of the outcome, this information needs to be used to improve or develop alternative approaches for the treatment of childhood disorders. With this framework in mind, we present what is known about the effects of stimulants, antidepressants, and antipsychotics on brain maturation (including animal studies that use more clinically-relevant dosing paradigms or relevant animal models). We endeavor to provocatively set the stage for altering treatment approaches for improving mental health in non-adult populations.

In this paper, we provide an overview of how the maturation of specific brain regions and stress exposure during windows of vulnerability initiate a series of events that render adolescents exceptionally susceptible to the development of depression. This stress-incubation/corticolimbic development cascade provides a means of understanding why depression emerges with such force and frequency in adolescence. The development of the prefrontal cortex, hippocampus, amygdala and ventral striatum is described from a translational perspective as they relate to stress exposure, onset, pathogenesis and gender differences in depression. Adolescent depression is a serious recurrent brain-based disorder. Understanding the genesis and neurobiological basis is important in the development of more effective intervention strategies to treat or prevent the disorder.

For almost 70 years, children have received stimulants for the treatment of attention deficit hyperactivity disorder [ADHD (initially called hyperkinetic syndrome)], with little understanding of the long-term effects of these drugs on brain development. The maturation and refinement of the brain during childhood and adolescence, including the overproduction and selective elimination of synapses, is based on genetic programming and experience. The effects of stimulant drugs during different stages of this process have unique short-term, acute effects that also influence their long-term effects. Chronic, pre-pubertal exposure alters the expected developmental trajectory of brain structure and function and results in a different topography in adulthood. The timing of exposure (childhood versus adolescence), the age of examination after drug exposure (immediately or delayed into adulthood) and sex influence the observable effects. Preclinical studies of the effects of stimulant exposure provide increased understanding about the impact of stimulant drugs on brain development and provide insight into new treatment options for ADHD and other disorders of childhood.

Abstract Background Much has been theorized about the emotional properties of the hemispheres. Our review of the dominant hypotheses put forth by Schore, Joseph, Davidson, and Harmon-Jones on hemispheric emotional valences (HEV) shows that none are supported by robust data. Instead, we propose that individual's hemispheres are organized to have differing HEVs that can be lateralized in either direction. Methods Probe auditory evoked potentials (AEP) recorded during a neutral and an upsetting memory were used to assess HEV in 28 (20 F) right-handed subjects who were either victims of childhood maltreatment (N = 12) or healthy controls. In a sub-population, we determined HEV by emotional response to lateral visual field stimulation (LVFS), in which vision is limited to one, then the other hemifield. We compare a number of morphometric and functional brain measures between individuals who have right-negative versus left-negative HEV. Results Using AEPs to determine HEV, we found 62% of controls and 67% of maltreated subjects had right negative HEV. There was a strong interaction between HEV-laterality and gender, which together accounted for 60% of individual variability in total grey matter volume (GMV). HEV-laterality was associated with differences in hippocampal volume, amygdala/hippocampal ratios, and measures of verbal, visual and global memory. HEV-laterality was associated also with different constellations of symptoms comparing maltreated subjects to controls. Emotional response to LVFS provided a convenient and complementary measure of HEV-laterality that correlated significantly with the HEVs determined by AEPs. Conclusion Our findings suggest that HEV-laterality, like handedness or gender, is an important individual difference with significant implications for brain and behavioral research, and for guiding lateralized treatments such as rTMS.