Physical and Hormonal Changes

1
Biological Foundations in Adolescent Development

• Physical and Hormonal Changes
• Cultural Psychological Responses to Puberty
• Neural Changes

2
Physical changes

• Puberty onset of sexual maturation
• Three neuroendocrine changes
• Gonadal
• Adrenal androgens
• Growth

3
Gonadal and adrenal androgen axes
4
Gonadal (HPG) axis
Gonadotropin releasing hormone (LH, FSH are
gonadotropins) (testes or ovaries) (sex
hormones testosterone estradiol increase
dramatically -- gonadarche) (see next slide)
5
Sex Characteristics (examples)
Primary Sex Characteristics Secondary Sex Characteristics
Production of sperm (spermarche) or development of eggs Development of sex organs Pubic and axillary hair growth Skin becomes rougher oily Voice deepens Slight enlargement of breasts known as breast buds (also, in ¼ of boys)

6
Adrenal androgen (HPA) axis
(ACTH adrenocorticotropic
hormone) (e.g., testosterone) (leading to
secondary changes)
7
Growth spurts and height changes
8
Body composition changes
Given that girls naturally develop a lower
muscle-to-fat ratio than boys during puberty, why
would any culture create physical ideals that
demand thinness in females once they reach
puberty? AND what are the health implications?
9
The Order of Pubertal Events (see Table 2.2)
10
Pubertal Caveat

• Virtually all the studies considered in the order
  of pubertal development have been conducted with
  White adolescents in the West
• Variations may exist in other groups (see p. 45
  e.g., Kikuyu culture in Kenya, Chinese girls,
  African-American girls and boys)

11
Earlier Puberty
Tanner Stage 2 (breast and pubic hair devt) by
age 10 in the majority of girls (68 in
Euro-American girls 95 in African-American
girls)
The downward trend in the age of menarche has
occurred in every Western country for which
records exist. Why?
12
Responses to Puberty

• Homework assignment
• Next section
• Cultural Psychological responses to puberty

13
Cultural Responses to Puberty Rituals in
Traditional Cultures

• 79 of cultures had puberty rituals for girls
• __________ (?) is the pubertal event that is most
  often marked by ritual
• Cultural views are mixed as to the reaction to
  menstruation (see Historical Focus box in
  chapter)

• 68 of cultures had puberty rituals for boys
  (e.g., vision quest ) (Roots video)
• Typically rituals require the young man to
  display courage, strength and endurance (often
  violent)

NOTE Globalization has been credited with the
decline in frequency of these rituals
14
Personal responses to puberty

• Behavior and emotions
• Problem behavior (e.g., aggression, conduct
  disorder symptoms, etc.) has been attributed to
  hormonal changes (but also to physical maturation
  and brain changes)
• Testosterone (T) can lower boys frustration
  tolerance ? readiness to engage in aggression
• Rapid hormonal changes are associated with
  depression, but hormonal storm view is far too
  simplistic. In fact
• Hormonal levels account for only a tiny
  percentage of the variance in adolescents
  negative affect social influences account for
  considerably more

15
Pubertal timing and adjustment

• There is a lot of research (which is conflicting)
  on the effects of timing of physical development
• Theoretically, being off-time creates more
  stress and vulnerability to adjustment problems

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Maturation - Girls

• According to Arnett, the effects of early
  maturation are especially negative for girls, who
  are at risk for a variety of problems
• Depressed mood, Negative body image, Eating
  disorders
• Delinquency, Substance use, School problems,
  Conflicts with parents
• Caveat Early-maturing girls with no history of
  behavior problems experienced fewer problems than
  did girls with a history of behavior problems who
  matured on time
• Late maturing girls have few of the problems that
  early-maturing girls have

17
Early Maturation - Boys

• The effects of early maturation are more mixed
  for boys
• Early maturing boys have
• More favorable body image
• Higher popularity
• Earlier involvement in substance use,
  delinquency, and sex

18
Late Maturation Boys

• Late maturing boys show evidence of problems
• Compared with boys who mature on time late
  maturing boys have higher rates of
• Alcohol use
• Delinquency
• Lower grades in school

19
Neural changes

• New research in cognitive and affective
  neuroscience (Intro to The Teenage Brain
  PBS-DVD Sci American podcast on the teen brain)
• Brain actively reorganizes itself cells and
  connections are pruned (for efficiency)
• Prefrontal cortex (planning and decision making)
  undergoes a growth spurt in early A and continues
  to develop throughout A
• Cortical-limbic pathways (thought-emotion
  connections) are slowly developing during
  adolescence (e.g., research on teens difficulty
  in reading emotions in peoples faces)
• Implications?
• Research example -- incarcerated adolescents
  displayed more impulsivity and poorer critical
  thinking than age-matched students (Chretien
  Persinger, 2000).
• Driving and multitasking
• Much more research needed