Chapters 11 12 Adolescence Psyc 311 Developmental Dr

Chapters 11 & 12 Adolescence Psyc 311 Developmental Dr. Wright

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Definition of Puberty • Pubertas – Latin word for “adult” • Narrow definition: The process by which an individual becomes capable of reproduction. – The activation of the HPG/HPA axis • Broad definition: The physical, psychological, and cultural changes that occur as the growing child transitions into adulthood.

Time Periods of Adolescence • Early adolescence – 10 to 13 years old – Continues to be pushed earlier • Middle adolescence – 14 to 17 years old • Late adolescence (early adulthood) – 18 to 22 years old – Continues to be pushed later?

physical changes… Ø Primary sex characteristics • The body organs and reproductive structures and functions that differ between women and men. • Gonads (testes and ovaries) Ø Secondary sex characteristics • Characteristics of the body that are caused by hormones, develop during puberty, and last through adult life. • Changes in genitals/breasts/voice • Pubic/body/facial hair

Tanner Stages • Sexual maturation in girls – – Growth of breasts/pubic hair Body growth Menarche Underarm hair/oil & sweat glands • Age of onset: 7 – 13 years

Tanner Stages • Sexual maturation in boys – – Growth of testes/pubic hair Body growth Growth of penis/change of voice Facial and underarm hair/oil & sweat glands • Age of onset: 9. 5 – 13. 5 years

Ø Rapid acceleration of physical growth • Adolescent growth spurt • 3. 5 (girls) to 4. 0 (boys) inches/year • ½ adult weight gained during adolescence Ø Changes in body composition • 3: 1 muscle to body fat ratio for boys • 5: 4 for girls • Emergence of sex differences in physical performance Ø Changes in circulatory and respiratory systems • Increase in size/capacity of heart and lungs

Two Roles of Hormones Ø Organizational role (life-long): – Modification of the organism early in life • primarily influencing its anatomy – Organization/structure of CNS • “Feminine” vs. “masculan-ized” brain Ø Activational role (specific to puberty): – Structural “remodeling” of brain – Increase in salience of sexual stimuli, sexual motivation – Development of secondary sex characteristics

Hormone Regulatory System • Endocrine system • HPA axis – Hypothalamus Pituitary gland Adrenals – Corticosteroids – Regulates body’s response to stress • HPG axis – Hypothalamus Pituitary gland Gonads (Testes/Ovaries) – Sex Hormones (Androgens/Estrogens) – Regulates sexual maturation

The biological changes of puberty can affect the adolescent’s behavior in at least three ways

impacts of puberty • Self-esteem – Body image • Moods – Fluctuation of moods – Due to hormones or environment? – “Storm and stress”: myth or fact? • Sleep patterns – Delayed phase preference – 9 hours: 1 am to 10 am • Family relations – Transformation of parent-child bond • Peer relations – Transformation of friendships, romantic relationships

Timing - individual Factors • Genetic factors – Timing and tempo • Environmental factors – – – Nutrition Body weight Health care Exposure to hormones/chemicals Family conflict Stepfathers

Timing - group Factors • Comparisons across socioeconomic groups – Impact of poverty – Dietary intake, health care, exposure to disease • Comparisons across countries • Comparisons across time periods – Secular trend

Early Maturation • Boys – Early maturation positives • Popularity, higher self-esteem – Early maturation negatives • Deviant, risk behaviors; more rigidity later • Girls – Early maturation positives • Popularity (cultural dependence) – Early maturation negatives • Lower self-esteem, eating disorders, emotions, deviant behaviors

Late Maturation • Boys – Late maturation positives • Higher levels of creativity, inventiveness – Late maturation negatives • Low self-esteem, low social competence • Girls – Late maturation positives • Thinner build – Late maturation negatives • Social withdrawal

Among the most important brain changes to take place at adolescence are those in the prefrontal cortex and limbic system.

The second wave…. Ø Longitudinal f. MRI studies reveal: • Period of rapid synaptogenesis and pruning – – Comparable to 1 st 3 yrs of life Growth: starts with onset of puberty Pruning: 1% of gray matter/yr Increased myelination (back to front) • Opportunity for massive cognitive growth and learning – Shift into Piaget’s formal operations

heightened arousal • Increased hormone activity – estrogen & testosterone • Sexual stimulation • Social status conflict • Increased neurotransmitter activity – Limbic system • heightened emotional sensitivity/reactivity • norepinephrine – Punishment/reward system • increased risk, stimulation-seeking behaviors • dopamine – Fluctuations in mood • Serotonin

(Pre) frontal lobe development • Final development of executive function – Planning/problem-solving – Impulse control – Seat of “sober 2 nd thought” • Processing of emotions – Understanding/responding to emotions • Full Maturation – sometime between adolescence and early adulthood • Coincides with child-onset schizophrenia – Failure in executive functioning

Timing of brain maturation • Limbic system matures early in puberty • Prefrontal cortex matures several years later • Heightened need for reward/stimulation – leads to increased stimulation-seeking behaviors • Underdeveloped “sober” assessment of risks • Increased cognitive/social demands – Creates cognitive overload – Difficulty with impulse control • Time gap may explain why adolescence is a period of heightened experimentation with risky behaviors – Increased violence • kids under 18 account for 25 of violent crime in US – Drug & alcohol experimentation – Unsafe sexual activities

Adolescents whose prefrontal cortical development is less mature than normal are more likely to have conduct problems. Populations most at risk?

Social implications • What should the social attitudes be about adolescent exposure to and involvement in high-stimulation/highrisk activities? • Sexual Activity • Drugs & Alcohol • Violence

Teen pregnancy • 750, 000 teens between 15 -19 years old become pregnant every year. – 2/3 rds between 18 -19 years old. • African American teens have highest rate – 134/1, 000 vs. 48/1, 1000 Caucasian teenagers • 57% end in birth (11% of all births in US) – 14% end in miscarriage – 29% end in abortion • 82% of those pregnancies were unintended

risk factors Ø Physical • Sexual maturation – 4 -5 years before psychological/emotional maturation – Becoming longer as puberty starts earlier • Brain development – Heightened activation of limbic system – Increased attraction to risky behaviors – Pre-frontal development incomplete

• SES factors – 50% of pregnancies occur in most impoverished populations • • Less opportunity for education Less access to birth control Reduced internal locus of control Exposure to other risk factors – drugs, alcohol, abuse, lack of parental monitoring • Desire for family/stability

consequences • Should we be concerned about this? • For teenage parents – mother in particular • • For baby For families For community Methods of prevention?

Why is teenage pregnancy higher in the US?

Impact of substance abuse • Alcohol/drug abuse – Greater potential impairment in learning – More widespread brain damage – Repeated exposure may effect path and quality of development – Due to reduction in plasticity, this damage cannot be corrected later! • So, does this mean all experimentation with drugs/alcohol bad?

• Should we be worried about exposure to graphic violence through media? – Why or why not?