Physical and Hormonal ChangesPhysical and Hormonal Changes

Cultural & Psychological Cultural & Psychological Responses to PubertyResponses to Puberty

Neural ChangesNeural Changes

Biological FoundationsBiological Foundations in Adolescent Developmentin Adolescent Development

Puberty – onset of Puberty – onset of sexual maturationsexual maturation

Three neuroendocrine Three neuroendocrine changes:changes:• GonadalGonadal• Adrenal androgensAdrenal androgens• GrowthGrowth

Physical changesPhysical changes

Gonadal and adrenal androgen axesGonadal and adrenal androgen axes

Gonadal (HPG) axisGonadal (HPG) axis

Gonadotropin releasing hormone

(LH, FSH are gonadotropins)

(testes or ovaries)

(sex hormones – testosterone & estradiol increase dramatically -- gonadarche)

(see next slide)

Sex Characteristics (examples)Sex Characteristics (examples)

Primary Sex Primary Sex CharacteristicsCharacteristics

Secondary Sex Secondary Sex

CharacteristicsCharacteristics Production of Production of sperm sperm (spermarche) or (spermarche) or development of eggsdevelopment of eggs

Development of Development of sex sex organsorgans

Pubic and axillary hair growthPubic and axillary hair growth SkinSkin becomes rougher & oily becomes rougher & oily VoiceVoice deepens deepens Slight enlargement of breasts known as Slight enlargement of breasts known as breast buds (breast buds (also, in ¼ of boysalso, in ¼ of boys))

Adrenal androgen (HPA) axisAdrenal androgen (HPA) axis

(ACTH = adrenocorticotropic hormone)

(e.g., testosterone)

(leading to secondary changes)

Growth spurts and height changes

Notice the differential timing in when growth spurts begin

Notice when the difference in final height is achieved

Body composition changesBody composition changesNotice prior to puberty boys and girls are very similar in muscle mass

During puberty body fat increases more for

girls than for boys

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?

The Order of Pubertal Events The Order of Pubertal Events (see Table 2.2)(see Table 2.2)

GIRLS

BOYS

Downy pubic hair

Appearance of breast buds

Growth spurt

Growth of sexual and

reproductive organs

Menarche

Secretion of increased

skin oil and sweat

Development of underarm

hair

Appearance of pubic hair

Deepening of the voice

Development of facial hair

Growth of testes

Growth spurt

Increased growth of

penis

Secretion of increased

skin oil and sweat

Pubertal CaveatPubertal Caveat

Virtually all the studies considered in Virtually all the studies considered in the order of pubertal development the order of pubertal development have been conducted with White have been conducted with White adolescents in the Westadolescents in the West

Variations may exist in other groups Variations may exist in other groups (see p. 45; e.g., (see p. 45; e.g., Kikuyu culture in Kenya, Chinese Kikuyu culture in Kenya, Chinese girls, African-American girls and boys)girls, African-American girls and boys)

Earlier PubertyEarlier Puberty

The downward trend in the age of menarche has

occurred in every Western country for which records

exist. Why?

Tanner Stage 2 (breast and pubic hair dev’t) by age 10 in the majority of girls (68% in Euro-American girls; 95% in African-American girls)

Responses to Puberty Responses to Puberty

Homework assignmentHomework assignment

Next section:Next section:• Cultural & Psychological responses to Cultural & Psychological responses to

pubertypuberty

Cultural Responses to Puberty: Cultural Responses to Puberty: Rituals in Traditional CulturesRituals in Traditional Cultures

68%68% of cultures had of cultures had puberty rituals puberty rituals for boys for boys (e.g., vision quest ) (e.g., vision quest ) (“Roots” (“Roots” video)video)

Typically rituals require the Typically rituals require the young man to display young man to display courage, strength and courage, strength and endurance (often violent)endurance (often violent)

• 79%79% of cultures had of cultures had puberty rituals puberty rituals for girlsfor girls

• __________ (?) is the __________ (?) is the pubertal event that is most pubertal event that is most often marked by ritualoften marked by ritual

• Cultural views are mixed Cultural views are mixed as to the reaction to as to the reaction to menstruation menstruation (see “Historical (see “Historical Focus” box in chapter)Focus” box in chapter)

NOTE: Globalization has been credited with the decline in frequency of these rituals

Personal responses to pubertyPersonal responses to puberty

Behavior and emotionsBehavior and emotions• Problem behavior (e.g., aggression, conduct Problem behavior (e.g., aggression, conduct

disorder symptoms, etc.) has been attributed to disorder symptoms, etc.) has been attributed to hormonal changes (but also to physical maturation hormonal changes (but also to physical maturation and brain changes)and brain changes)

• Testosterone (T) can lower boys’ frustration Testosterone (T) can lower boys’ frustration tolerance tolerance readiness to engage in aggression readiness to engage in aggression

• Rapid hormonal changes are associated with Rapid hormonal changes are associated with depression, but “hormonal storm” view is far too depression, but “hormonal storm” view is far too simplistic. In fact…simplistic. In fact…

• Hormonal levels account for only a tiny percentage Hormonal levels account for only a tiny percentage of the variance in adolescents’ negative affect – of the variance in adolescents’ negative affect – social influences account for considerably moresocial influences account for considerably more

Pubertal timing and adjustmentPubertal 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

• According to Arnett, the effects of early According to Arnett, the effects of early maturation are especially maturation are especially negativenegative for for girls, who are girls, who are at risk at risk for a variety of for a variety of problems:problems:

Depressed mood, Negative body image, Depressed mood, Negative body image, Eating disordersEating disorders

Delinquency, Substance use, School Delinquency, Substance use, School problems, Conflicts with parentsproblems, Conflicts with parents

Caveat: Early-maturing girls with no history Caveat: Early-maturing girls with no history of behavior problems experienced fewer of behavior problems experienced fewer problems than did girls with a history of problems than did girls with a history of behavior problems who matured on timebehavior problems who matured on time

• Late maturing girls have few of the Late maturing girls have few of the problems that early-maturing girls haveproblems that early-maturing girls have

Maturation - GirlsMaturation - Girls

• The effects of early maturation are more The effects of early maturation are more mixed for boysmixed for boys

• Early maturing boys have:Early maturing boys have: More favorable body imageMore favorable body image Higher popularityHigher popularity Earlier involvement in substance use, Earlier involvement in substance use,

delinquency, and sexdelinquency, and sex

Early Maturation - BoysEarly Maturation - Boys

Late Maturation – Boys Late Maturation – Boys

• Late maturing boys show evidence of Late maturing boys show evidence of problemsproblems

• Compared with boys who mature “on Compared with boys who mature “on time” late maturing boys have higher time” late maturing boys have higher rates of:rates of:

Alcohol useAlcohol use DelinquencyDelinquency Lower grades in schoolLower grades in school

New research in cognitive and affective neuroscience New research in cognitive and affective neuroscience (Intro to “The Teenage Brain” PBS-DVD & Sci American podcast on the teen brain)(Intro to “The Teenage Brain” PBS-DVD & Sci American podcast on the teen brain)

• Brain actively reorganizes itself – cells and connections are Brain actively reorganizes itself – cells and connections are pruned (for efficiency)pruned (for efficiency)

• Prefrontal cortex (planning and decision making) undergoes a Prefrontal cortex (planning and decision making) undergoes a growth spurt in early A and continues to develop throughout Agrowth spurt in early A and continues to develop throughout A

• Cortical-limbic pathways (thought-emotion connections) are Cortical-limbic pathways (thought-emotion connections) are slowly developing during adolescence (e.g., research on teens’ slowly developing during adolescence (e.g., research on teens’ difficulty in reading emotions in people’s faces)difficulty in reading emotions in people’s faces)

Implications?Implications?• Research example Research example -- -- incarceratedincarcerated adolescents displayed more adolescents displayed more

impulsivity and poorer critical thinking than age-matched students impulsivity and poorer critical thinking than age-matched students (Chretien & Persinger, 2000).(Chretien & Persinger, 2000).

• Driving and multitaskingDriving and multitasking Much more research neededMuch more research needed

Neural changesNeural changes