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Emerging Issues in Adolescence: Implications for Low and Middle Income Countries Robert Wm. Blum MD, MPH, PhD William H. Gates Sr Professor Bloomberg School of Public Health Director, JHU Urban Health Institute prepared for International Association of Adolescent Helath Istanbul, Turkey 13 June 2013
Epigenetics Epigenetics is the missing link between environment and the development of diseases. Genetics explain only a small fraction of human disease at any age.
Epigenetics Genes and environment interact through epigenetic processes to influence behavior
How Epigenetics Works Epigenetics controls genetic influence through methylation (-CH3 group) to one of the proteins in DNA sequence effectively silencing the gene
Epigenetic Control of Gene Expression histone methylation and acetylation DNA methylation small RNAs
Obesity Diabetes Cancer Folate and B12 have transgenerational effect on decreased expression of the gene that controls skin color and weight Waterland and Jirtle. Mol Cell Biol 2003; 23:5293
Nutrition, Epigenetics and the Social Determinants of Disease • Nutrition can alter gene expression without altering gene structure – the case of obese yellow mice • The association of the Dutch famine on schizophrenia among adult off-spring of women food deprived during their first trimester
Adolescence is a time for great risk and opportunity. It is the stage of life of the greatest risk for… • Depression, anxiety, conduct disorders (early/mid adolescence) • Schizophrenia (late adolescence) • Alcohol and drug use (mid/late adolescence)
Some Developmental Phenomena occur Cross-species • Earlier maturation of females • Greater risk taking of males • Change in sleeping patterns • Increased alcohol consumption
Features of Adolescent Brain Development • Pruning and elimination of synapses (grey matter) • Speed of information flow is increased by myelination (white matter) • The relative proportion of white matter increases over grey • Development occurs posterior to anterior • Changes lead to a more streamlined and energy efficient brain
Executive Control Develops in Pre-frontal cortex • Selective attention • Planning/decision making • Response inhibition • Response speed-accuracy adjustment
Prefrontal Cortex regulates emotions… the currency of human relations • Regions that control social behaviors and emotions are closely related • Adolescents experience more stress than adults or children • Exacerbated by phase delay in sleep onset • More external stressors • Higher baseline levels
Prefrontal Cortex integrates cognitive with emotional information • Inhibition of emotional response critical for cognitive and social functioning • Initially bottom-up (affective) and subsequently top-down (cognitive) functioning
Contexts Matter in the lives of Young People. They influence…Brain DevelopmentGenetic regulationDecision Making