Adolescence

• Adolescence definition: Sawyers et al (2018):


  10-24 years old.
• Steinberg et al (2017)


  Looked at adolescent behaviours in 11 countries and found that:

  Self-regulation improves gradually between 10-20 years old and stabilises at around 22-26. Also found this effect is not just seen in weird countries making it a universal trait of adolescence.

  Sensation seeking peaked in late teens but dropped off in early 20s.
• Walker et al (2019) 


  In adolescent rodents, increased risk taking, exploration, impulsivity were seen alongside changes in social behaviour.
• Logue et al (2014)


  Adolescent mice drink more when in social groups (much more than adult mice, or even them when alone).
• Powers and Casey (2015) 


  Most mental health conditions start in adolescence including schizophrenia, mood disorders, and anxiety disorders.
• Lebel et al (2011)


  White matter increases during adolescence and grey matter decreases, and the amount of grey matter decreases region by region the older you get. Not much overall change in total brain volume.
• Mills et al (2016)


  Across 4 western countries grey matter volume decreases by 1.5% annually during adolescence. White matter volume increases by 1% annually.
• Tammes et al (2017) 


  Occipital cortex is the only region which stops developing after 13/14 years old. Frontal, parietal and temporal cortex continue to develop in thickness, surface area and volume.
• Why does the grey matter decrease and white matter increase matter? 


  We don't know - but we think its to increase efficiency because myelination and axonal growth cause an increase in white matter and requires a grey matter decrease. Synaptic pruning also requires grey matter decrease because synapses which aren't being uses are remover (ENVIRONMENTALLY BASED).

  X This is why its such a huge issue for children to put to death or serve life without parole for crimes, without these processes we cannot make informed decisions and our decisions are based on our environmental conditions.
• Huttenlocher and Dabolkar (1997)


  Synaptic re-organisation continues into adolescence in PFC.
• Goddings et al (2014) 


  Different stages of puberty causes the brain to develop differently regardless of the age of the individual- meaning comparative studies in adolescence regarding age become less generalisable.
• AAA foundation (2017) 


  Percentage death risk with passengers for those under 21 is ~300% when there are 3+ passengers in the car. Alone this is ~40%, meaning adolescents are more likely to engage in risky behaviour when with friends.
• Gardner and Steinberg (2005) 


  When participating in a speed driving game, both young and older adolescence and adults are pretty similar in the number of risks they take. But for adolescents (13-16) this increases much higher than younger adolescents and a lot more than adults.
• Williams (2000) 


  In a game of Cyberball (a social exclusion game), there was a significant drop in mood in adolescents and young adolescents. Suggesting they're sensitive to social exclusion compared to adults (who didn't drop as much).
• Blakemore and Mills (2014): The See-saw model: 


  Adolescents have to balance decisions with 'reasonable' considerations with social ones, which have a large impact. If an adolescent was considering taking drugs, they would have to balance the social factors with health/ the law and novel-seeking but novel-seeking would outweigh the low and health factors because its backed up with social recognition.
• Knoll et al (2015)


  All age groups show significantly different risk magnitude when dealing with social influence vs being alone. Magnitude decreases of age.

  Young adolescents (12-14) risk perception is influenced by teenagers.
• Andrews et al (2019)

  Adolescents reported more significantly enjoyment looking at social photographs compared to adults, they also spent more time looking at social photographs.
• Paluck et al (2015)


  In peer conflict interventions, student conflict reduced by 25%, and the effect was stronger when the students leading the campaign were more highly liked and connected with peers.
• Solmi et al (2022) 


  Most mental illnesses start or peak in adolescence e.g., OCD, eating disorders and substance abuse.

  
• NHS Digital (2017)


  Mental health conditions in crease with age from 5.5% in 204 year olds to 16.9% in 17-19 year olds.

  In childhood, mental illness is higher in boys, ages 11-16 it is equal between boys and girls, but in 17-19 year olds girls double the rate of boys in mental illness prevalence.

  In adolescence emotional disorders are the most common by far.
• Castelpietra et al (2022) 


  In European countries, the most common disorders for women to live with are anxiety and depression, eating disorders, as well as self harm (which did not result in death). For boys anxiety, depression, conduct problems, alcohol and drug use were especially high and self harm in boys was higher than in girls.

  In both boys and girls, self harm, drug use (and alcohol use in boys) were associated with years of lives lost.
• Ford et al (2007)


  Psychiatric disorders are more common in adolescents who are in care and children with high levels of deprivation. In care was the highest by far.
• Studies have shown persistence of mental disorders over 3 years.

  50% of persistence after 3 years of having disorder.
• Predictors of psychopathology persistence

  Conduct disorder: peer relationship problems, poor family functioning, and rented housing

  ADHD: Peer relationship problems, neurodevelopment disorder

  Anxiety: Peer relationship problems, lower family income and parental burden due to psychopathology.

  Depression: parental psychological destress
• Pierce et al (2021)


  In people who had consistently poor mental health, there was a large increase in mental health severity. In deteriorating class this increase increased as pandemic went on, believed this was caused by women, people with previous mental illness and ethnic minorities.
• NHS Digital (2022)


  Deterioration for adolescent mental health maintained in 2022 in both sexes.
• How does synaptic pruning depend on the environment?


  Synapses that are used are strengthened, ones that aren't are pruned back, meaning that the environment 'fine-tunes' brain tissue according to the species specific environment.
• Kuhl et al (2004)


  In 9 month old American babies (who lost sound distinction ability), the children who were taught Chinese by a real person learnt sound distinction similar to that of a native Chinese speaker. Video and sound only conditions show that no re-learning occurred. Therefore this is socially conditional.
• NSCoDV (2014) 


  Brain plasticity and the ability to change behaviour lessens over time.
• Crone and Dahl (2012)


  In adolescence brain re-jiggling occurs in brain structure, specifically in frontal and parental lobes which undergo structural and functional development.
• Knoll et al (2016) 


  The older you are, the higher you score on relational reasoning task.
• Chierchia et al (2019) 


  Adolescents only improved on a face proprioception task not in relational reasoning or numerosity discrimination.
• Affect: 


  Underlying experience of feeling, emotion or mood. Characterised along 2 dimensions: valence and arousal.
• Valence: 


  Dimension of affect that refers to subjective spectrum of positive-to-negative evaluation.
• Arousal: 


  One's overall level of alertness, attention or energy level.
• Somerville et al (2013) 


  Adolescent emotions tend to be more complex and nuanced than children and self-conscious emotions tend to peak in adolescence.
• Marshal et al (2020)


  Adolescents display increased reward pursuit.
• Klein et al (2021) 


  Adolescents display heightened threat avoidance.
• Vink et al (2014)


  Neural activity in adolescents suggests heightened sensitivity to social-emotional information.
• Davidow et al (2019) 


  Older adolescents show faster response times when learning to respond to stimuli which predicts rewards compared to children and adults.