Biological Aspects of Adolescence
Sam Mathews, Ph.D.
School of Psychological and Behavioral Sciences
The University of West Florida
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Puberty
Changes in physical attributes
Neurological changes
Health practices
Biological Bases
• The Endocrine System and the Puberty
Process:
– HypothalamusGonadotropin Releasing
Hormones (GRH)Pituitary Gland
– Pituitary gland GonadotropinGonads
(ovaries/testes)
– Gonadsstimulate release of sex hormones
(estrogens/androgens) that stimulate
secondary sex characteristics
Puberty Process:
• Process begins approximately 2 years
prior to initial secondary sex characteristic
changes;
• Hypothalamous secretions typically
increase during deep sleep;
• Males and females produce both
estrogens and androgens but in different
proportions;
Puberty Process: Physical
Changes
• Secondary sex characteristics
– Body/pubic hair (males and females)
– Breast enlargement (most obvious in females)
– Increase in growth rate (females and males)
– Changes in voice (most obvious in males)
– For females, increase in fat to muscle cell
ratio (increase in fat cells relative to muscle
cells)
Puberty Process: Physical
Changes
• For females: as level of estrogen increases, the
hypothalamus produces Gonadotropin Inhibiting
Hormones (GIH). This inhibits the production of
estrogen by the ovaries;
• The periodic cycle of increases and decreases
in estrogen controls the ovulation cycle.
• Estrogen is stored in fat cells so the increase in
fat cells relative to muscle cells allows the critical
level of estrogen necessary for ovulation.
Neurological Changes
• Myelinization
– Fatty tissue surrounding nerve cells in the
brain
– Increases the efficiency of transmission of
signals across the synaptic junctions in the
brain
– Made up of cholesterol and proteins
– Rapid increase of myelinization during and
after puberty through adolescence
Neurological Changes
• Elaboration of synaptic connections
– Neurons form new connections based on
experience throughout the lifespan;
– Plasticity still a major force—brain responds
to stimulation
Neurological Changes
• Frontal and pre-frontal cortex major area
of development across adolescence
– Maturation of neurological systems that allow:
• Planning
• Regulation of emotion
• Monitoring
– Prediction based on this is that across
adolescence, ability to forecast, anticipate
long-term outcomes and recognize risk is
limited
Health Practices and Puberty
Process
• Nutrition—balanced diet including
appropriate levels of carbohydrates
(myelinization)
• Sleep—reasonable opportunities for deep
sleep (supports initiation and maintenance
of puberty process)
• Limited alcohol consumption—some
evidence that alcohol interferes with
hormonal balance of pubescent females
Puberty Process: Pre and Early
Adolescents
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Direct effects hypothesis—the onset of
puberty, in itself, brings about an
unstable and stormy time in one's life
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Mediated effects hypothesis—the impact
of the onset of puberty is the result of the
interaction of cultural and psychological
factors with the biological changes
Social Changes Associated with
Puberty
As physical changes occur, others treat the
young adolescent differently (self-fulfilling
prophecy);
– societal expectations change--schooling;
position in the family--perhaps caring for
younger siblings, increased household
responsibility
– target for marketing--music, clothes, alcohol,
tobacco
Pubertal Timing and Social-CulturalEmotional Factors
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“Early maturing girls who experienced
higher levels of stressful live events
tend to report more depressive
symptoms in the junior high (gr.7, 8.
9) and early high school years (gr 1011)”
(Ge, Conger, & Elder, 2001)
Pubertal Timing and Social-CulturalEmotional Factors
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Early maturation, early onset of dating,
and emotional distress predicts initiation
of substance use (tobacco, alcohol,
marijuana) across two year period…most
likely due to interactions with older
peers…
Pubertal Timing and Social-CulturalEmotional Factors
A review of studies examining pubertal status,
parental and peer factors, the following was
observed:
“…peers and parents appear to account for much
of the total variance (77%) in early substance
use. “
Brent Walden, Matt McGue, William G. Iacono, S.
Alexandra Burt, Irene Elkins (2004)
Pubertal Timing and Social-CulturalEmotional Factors
• “Many of the studies we have reviewed
confirm current thinking that adolescence
does not inevitably spell trouble”
(Buchanan, Eccles, & Becker, 1992)
Gene—Environment Effects
• Passive Genotype Environment Effect
– Biological parent(s) provide environmental structure;
most frequently seen in infants and younger children
• Evocative Genotype Environment Effect
– Genotypic behaviors evoke positive responses from
the environment; frequently seen in extended families
and peers; must have access to others
• Active Genotype Environment Effect
– Individuals actively seek out or create environments
that match their genotypic attributes; frequently seen
in older children and adolescents; must have access
to environments
– (Sandra Scarr, 1993)
Pubertal Timing and Social-CulturalEmotional Factors
• Resiliency: ability to encounter stressful
and risky situations and emerge without
injury or harm
• Resiliency factors for adolescents (and
others) can include:
– Family
– Peers
– Teachers
– Other significant individuals
Discussion Questions:
• Describe your own experience as you matured
into puberty?
• How did your parents prepare you for puberty
and entrance into adolescence?
• As you think about the information from the text
on rites of passage into puberty, what rites of
passage did you experience as you moved from
childhood to adolescence?
• How did your experiences differ from those
described in the text?