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 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

Epigenetics

Epigenetics controls genetic influence through methylation (-CH3 group) to one of the proteins in DNA sequence effectively silencing the gene

How Epigenetics Works

Epigenetic Control of Gene Expression

DNA methylation

smallRNAs

histonemethylationand acetylation

Folate and B12 have transgenerational effect on decreased expression of the gene that controls skin color and weight

ObesityDiabetesCancer

Waterland and Jirtle. Mol Cell Biol 2003; 23:5293

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

Nutrition, Epigenetics and the Social Determinants of Disease

•Depression, anxiety, conduct disorders (early/mid adolescence)

•Schizophrenia (late adolescence)

•Alcohol and drug use (mid/late adolescence)

Adolescence is a time for great risk and opportunity. It is the stage of life of the greatest

risk for…

•Earlier maturation of females

•Greater risk taking of males

•Change in sleeping patterns

•Increased alcohol consumption

Some Developmental Phenomena occur Cross-species

• 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

Features of Adolescent Brain Development

•Selective attention•Planning/decision making•Response inhibition

•Response speed-accuracy adjustment

Executive Control Develops in Pre-frontal cortex

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

•Inhibition of emotional response critical for cognitive and social functioning

•Initially bottom-up (affective) and subsequently top-down (cognitive) functioning

Prefrontal Cortex integrates cognitive with emotional information

Contexts Matter in the lives of Young People. They influence…

Brain DevelopmentGenetic regulationDecision Making