L11 - Adolescent Development

Question 1

What are the three stages of adolescence?

Answer 1

Early (10-15)
- Rapid growth and development of secondary sexual characteristics
- Concrete thinking
- Developing body image
- Frequent mood changes
- Struggles with being dependent
- Intense friendships
- Exploration of sexuality
Middle (14 - 17)
- Brain growth – prefrontal cortex
- Moves towards abstract thinking
- Creates body image
- Risky behaviours; argues with authority
- Powerful influence of peer group
- Form stable relationships
Late (16-19
- Physically mature
- Abstract thinker, plans for the future
- Usually comfortable with body image
- Family dynamics shift toward equal adult-adult relationship
- Less influence of peers – individual friendships and relationships most important
- Mutual and balanced sexual relations)

Question 2

How has adolescence changed in definition?

Answer 2

• Adolescence in 1920
  
  • Puberty onset - age 14.6 for girls
  • School leaving age - 14 (UK)
  • Employment age (full-time) - 14
  • Teenage pregnancy - approx 2.5% (still lower compared to now due to contraceptive)
• Adolescence now
  
  • Puberty onset - age 10.5 for girls (maturity gap - mismatch between biological and social)
  • School leaving age - 17 in Australia
  • Employment age - 17
  • Teenage pregnancy - 2.8%

Question 3

What is the basic overview of development in adolescence for boy and girls?

Answer 3

Biological things occur earlier, if the environment is better

Question 4

How is puberty onset and obesity related?

Answer 4

• Obese girls, defined as at least 10 kilograms (22 pounds) overweight, had an 80% chance of developing breasts before their ninth birthday and starting menstruation before age 12 – the western average for menstruation is about 12.7 years.
• Joyce Lee of the University of Michigan, US, followed 354 girls who were either normal weight, at risk of being overweight, or overweight from age 3 to age 12.
  
  • Lee found a strong association between elevated body weights at all ages and the early onset of puberty as determined by breast development and the onset of menstruation.
  • While previous studies have noted a relationship between obesity in girls and early puberty, it remained unclear which condition caused the other.
  • By tracking the girls from such an early age, Lee says, “our study shows that it is increased body fatness that causes the early onset of puberty and not the other way around”.

Question 5

How do you measure pubertal maturation?

Answer 5

• Only way you can do this in practice is ask the child themselves
• Hormonal changes
  
  • Most dramatic increase in testosterone occurs in puberty
  • Levels of hormones increasing

Question 6

What cognitive changes occur in adolescence?

Answer 6

1. Executive functions
   
   • Deductive reasoning
   • Information processing
   • Individuals become more capable of abstract, multidimensional, planned and hypothetical thinking as they develop from late childhood into adolescence
   • Changes in brain structure depend on chronological age (so executive functions)

Question 7

What are the developments in the prefrontal cortex?

Answer 7

• Dorsolateral prefrontal cortex → Working memory, Planning
• Ventromedial prefrontal cortex → Calibration of risk and reward
• • 6-9 year olds - Drew equally from good and bad decks
• 10-12 year olds and 13-15 year olds - Improved over time. By the final block they were drawing from the good decks, about 55% and 60% of the time, respectively
• 18-25 year olds → Drawing from the good deck nearly 75% of the time by the last block
• So ability to control impulses improves

Question 8

What is increased efficiency? (cognitive changes)

Answer 8

• Myelination and localised synaptic pruning in PFC
  
  • Both of which increase the efficiency of information processing
• Getting increased amount of white matter on pathway (e.g. for risk behaviour)
• Brain and social cognition
  
  • (a) Age-related changes in white-matter density along the putative fronto-temporal (top arrow) and the occipito-temporal (bottom arrow) pathways [48]; 36 children and adolescents, aged 10–19 years, were scanned at least twice (average interval of 3.5 yrs). Note that the changes in the fronto-temporal pathway replicate the original cross- sectional data [16] whereas those in the occipito-temporal pathway suggest maturation of a system involved in processing of biological motion.
  • (b) Activation of regions along the left superior temporal sulcus during the perception of biological motion by adult subjects [55].
  • (c) Developmental changes in the latency, recorded with electroencephalography, of the cortical response to the presentation of black-and-white photographs of faces (9–14 subjects per age group)
  • Negative correlation between age and left pSTS ⁄ TPJ–arMPFC connectivity during social (embarrassment/guilt) relative to basic emotions (disgust/fear).
    
    • An interpretation of the age-related decrease in connectivity is that, in order to accomplish this task, adolescents require not only higher activity in arMPFC but also stronger co-activation of the mentalising system than do adults. This may be because the maturing network in adolescents is less efficient in accomplishing the task. Continuing synaptic elimination and axonal myelination and perhaps developing axonal calibre during adolescence, within regions of the brain involved in mentalising, may act to increase the efficiency of the system.
    • Less connectivity between two regions, less connectivity = more efficient we are

Question 9

What is increased connectivity between PFC and limbic system?

Answer 9

• The interplay between cognitive and emotion-related processes” – social cognition
• Important for…
  
  • Peer-peer interactions
  • Processing of verbal and non-verbal cues (processing biological motion)
  • Discrimination of facial expressions
  • Attentional enhancement of the neural response to socially salient stimuli
• E.g. happy but not sad faces elicit significant BOLD response in the amygdala in adolescent subjects (age 13-17) – as opposed to adults
• E.g. “maturation of the adolescent’s ability to extract quickly the relevant cues from the face of a peer
• Even though socially complex, our connectivity isn’t quite there at the same time - such as subtlety
• Two things are happening as age increase during adolescence:
  
  • 1) The neural systems involved in social information processing are becoming more efficient
  • 2) The influence of the affective systems on the decision-making systems is decreasing

Question 10

What is the impact of social environment?

Answer 10

• Response inhibition
• Calibration of risk and reward
• “Whereas studies of people’s responses to hypothetical dilemmas involving the perception and appraisal of risk show few reliable age differences after middle adolescence, studies of actual risk-taking (e.g. risky driving, unprotected sex, etc) indicate that adolescents are significantly more likely to make risky decisions than are adults”
• • When playing by themselves on adolescents and youths take risks but increases more when their friends are present
• So even if they have better executive functions, may not be performing in that way

Question 11

What are the socio-emotional changes in adolescence?

Answer 11

• Hormonal changes lead to arousal sensation and reward orientation
• Changes in frequency of parent-adolescent conflict more closely linked to pubertal maturation than to age
• In a large group of 11-14 year olds, there was no significant correlation between age and sensation-seeking, but a significant correlation between sensation-seeking and pubertal stage
• There is substantial evidence that adolescents engage in dangerous activities despite knowing and understanding the risks involved

Question 12

What are the effects of oestrogen and testosterone on the brain?

Answer 12

• Organisation
  
  • Occur pre & perinatally
  • In males, testosterone influences the development of neural circuits
  • The abscence of testosterone results in a female neural phenotype
• Activation
  
  • Occur at puberty
  • Gonadal steroid hormones act on dormant neural circuits to elicit adult reproductive behaviours

Question 13

What is the development of regulatory competence?

Answer 13

• During adolescence, regulatory systems are gradually brought under the control of central executive functions
• INTERFACE OF COGNITION AND EMOTION
  
  • 1. The development of an integrated and consciously controlled “executive suite” of regulatory capacities is a complex and lengthy process. Yet, adolescents confront major, emotion-laden life dilemmas from a relatively early age. E.g. sexual relationships, school assessments
  • 2. Cognitive development (e.g. executive control) generally occurs later than puberty-linked emotional changes - so hormones are responsible for cognitive changes
• POWERFUL ENGINE BUT AN UNLICENCED DRIVER
• As puberty gets earlier and the gap widens, are future generations of adolescents at greater risk of poor outcomes and psychopathology typical of externalising problems?

Question 14

Why is adolescence so hard?

Answer 14

• Layers of changes: physically, cognitively, emotionally
• Different rates of change: chronologically versus hormone-linked, cognitively versus emotionally, from peers, from the environment, from society
• While all this happens you look like a small adult – and sometimes behave like one too