Week 3 - RF Lecture Developmental - Brain Development during Adolescence

What is Adolescence?

• the transition between childhood + adulthood

• begins with puberty, typically ages of 10-14

• traditionally, was considered to end around 18-21

• Sawyer et al (2018) = proposed extending it to 24

• involves physical, psychological + social changes

HPG Axis (hypothalamic-pituitary-gondadal)

• regulates hormonal changes that initiate puberty + reproductive maturation

Three Main Components:

• hypothalamus = signals the pituitary gland

• pituitary gland = releases hormones that stimulate the gonads

• gonads (ovaries/testes) = produce sex hormones involved in puberty

Physical + Psychological Changes/Development

• physical = increases in height, weight, muscle mass, organ development

• psychological = identity development, new relationships, greater responsibility

Brain Development = Synaptogenesis

• the formation of new synaptic connections between neurons

Brain Development = Synaptic Pruning

• the elimination of less frequently used synaptic connections, while frequently used connections are strengthened

= early in development, the brain produces many connections - not all are needed

= during pruning, connections that are used regularly are maintained or strengthened. Less- used connections are removed

= helps refine brain networks during development

Myelination

Myelin = a protective, insulating sheath surrounding axons

• myelination continues during adolescence

• increases the speed of electrical signal conduction along axons

= axon is like an electrical wire - myelin is the insulation, allowing electrical signals to travel more quickly and efficiently

• brain becomes more myelinated = communication between brain regions becomes faster

Grey Matter

• contains neural cell bodies and many synapses

• generally decreases in certain regions during adolescence

• changes are linked to synaptic reorganisation and pruning

= grey matter reaches a peak around the onset of puberty in some regions, then decreases - linked to synaptogenesis followed by pruning

White Matter

• contains mainly myelinated axons

• generally increases during adolescence

• increase are linked to myelination = axons becoming more myelinated

• changes are particularly significant in the frontal and parietal regions

Giedd et al. (1999) - MRI Research

• research focus = how brain structure changes during childhood + adolescence

• method = longitudinal MRI

• Key findings:

• white matter increased with development

• grey matter showed a non-linear developmental pattern, including a peak around puberty in certain regions

• important structural changes occurred in frontal + parietal regions

= helped demonstrate that substantial brain maturation continues beyond early childhood

Gogtay et al. (2004) - Brain Maturation

Research Method = longitudinal study, 13 ppts aged 5-20, anatomical brain scans approx every 2 years

Key Findings:

• different brain regions mature at different rates

• regions involved in spatial perception mature relatively early

• frontal regions associated with planning + critical thinking continue developing into the early 20s

• temporal regions associated with learning + memory are among the later regions to mature

= brain doesn’t develop everywhere at the same time

= helps explain why adolescent cognitive abilities develop gradually

Cognitive & Social Development - Cognitive Control

= the ability to regulate thoughts + behaviour to achieve goals

Three Main Components:

• inhibitory control = resisting impulses

• working memory = holding + manipulating information temporarily

• performance monitoring = detecting errors + evaluating behaviour

Risk-Taking in Adolescents

• developing cognitive control and heightened sensitivity to immediate and social rewards

The Social Brain

= a network of brain regions involved in understanding social information

Theory of Mind (mentalising)

= the ability to understand + interpret our own and other’s mental states and intentions

• eg - your friend is quieter than usual, so you think maybe they are sad, angry…= thinking about their possible mental state

Blakemore (2008)

• research comparing adolescents + adults during theory-of-mind tasks

= adolescents showed greater activation in the dorsomedial prefrontal cortex than adults (dMPFC)

Brunett et al. (2009)

Examined emotional aspects of theory of mind, including fear and anger:

• adolescents showed greater dMPFC activation than adults when processing social versus basic emotions

• adults showed greater anterior temporal cortex activation than adolescents in the same comparison

• = shows that both are capable of understanding social situations, but they can recruit brain regions differently

Van den Bos et al. (2010) - Trust and Reciprocity

Research Focus = how trust and reciprocity develop with age

• trust = willingness to rely on another person

• reciprocity = responding to another person’s actions (eg, returning cooperation)

Key findings:

• trust + reciprocity generally increased with age when the ppt faced less risk

• also increased when the other player would benefit more = only among 22 year olds

Puberty + Mental Health - Angold & Costello (2006)

• before puberty = depression rates are relatively low and similar in girls and boys

• after puberty = adolescent girls are approx twice as likely to experience depression

Puberty + Mental Health - Galvao et al. (2014)

• earlier puberty compared with peers is associated with increased depressive symptoms + anxiety, particularly among girls

Puberty + Mental Health - Miranda-Mendizabal et al. (2019)

• adolescent boys are more likely than girls to develop substance abuse use disorders and to die by suicide

Social Media + Adolescent Mental health

• adolescents are particularly sensitive to peer feedback

• some studies suggest associations between social media use, depressive symptoms + suicide-related outcomes

• HOWEVER - research findings are mixed

• many studies are correlational

• correlational studies cannot prove social media causes depression = cannot establish causality, direction of effect or rule out third variables

Achterberg et al. (2022) - Social Media + Brain Development

• RF = longitudinal associations between social media, mental well-being + structural brain development

Findings:

• greater social media use was associated with small differences in brain regions involved in social cognition + self-control

• lower mental well-being was associated with slightly smaller surface areas in regions involved in emotion + social understanding

• there was no clear, consistent association between social media use + mental health

= challenges the oversimplified claim that social media is necessarily harmful to adolescent mental health

Protective Factors for Adolescent Mental Health

• physical activity = Belcher et al - exercise may promote resilience + emotional regulation

• sleep = Galvan - poor sleep is associated with poorer memory, processing speed + executive function

• diet = O’Neil et al - better quality diets are associated with better mental health

• social support = Van Harmelen et al - Family + friendships can buffer the relationship between childhood adversity + later depression