Lecture 4 - Cognitve Devleopment In Adolescence Flashcards
What is adolescence?
Defined as the developmental stage that begins with the onset of puberty and ends when individuals reach adulthood
Distinct increase in brain plasticity, pubertal maturation
Puberty
Period of transition to mature fucntion
A series of distinct but interlined hormonal cascade
3 phases of development - feta;, neonatal and adult
Key terms:
Thelarche - onset ofg breast development, oestrogen effect
Pubarche - onset of sexual hair growth - androgen effect
Menarche - onset of menses
Spermarche - appearance of spermatozoa in seminal fluid
Gonadarche - onset of pubertal function of the gonads
Adrenarche - onset of the adrenal androgen production, contributing to pubarche
When does it begin?
- a response to a number of signals that lead to significant increases in GnRH secretion and marked elevations of testosterone and oestrogen
Two distinct but overlapping processes:
- adrenarche: awakening of the adrenal glands 0 occurs 6-8 years old - a rise in 3 adrenal steroid hormones
- gonadarche: follows adrenarche 1-2 years later - takes 4-5 years
Growth axis: growth hormone (GH) increases at puberty when stimulate by rising sex steroids
The features of puberty develops in similar sequence
But huge variability in the age at which they develop (onset) and speed of development (tempo)
Girls: Thelarche the 1st sing - menarche occurs later (1.5-3 years later)
Boys: testicular enlargement 1st sign - heigh spurt midpuberty
Pubertal development (tanner, 1962,1978)
Pubic hair scale
- stage 1: no hair
- stage 2: downy hair
- stage 3: scant terminal hair
- stage 4: terminal hair that fills the entire triangle overlying the pubic region
- stage 5: termina hair that extends beyond the ingunial crease onto the thigh
Female breast development:
- stage 1: no glandular breast tissue palpable
- stage 2: breast bud palpable under the Areola
- stage 3: breast tissue palpable outside areola, no Areola development
- stage 4: areola elevated above the contour 0f the breast, forming a double scoop appearance
- stage 5: Areola mound recedes into single breast contour with Areola hyperpigmentation, papillary development and nipple protrusion
Male external genitalia scale:
- stage 1: testicular volume <4ml or long axis <2.5cm
- stage 2: 4-8/l(or 2.5-3.3cm long)
- stage 3: 9-12 ml (or 3-4.4cm long)
- stage 4: 15-20ml (or 4.1-4.5 cm long)
Stage 5: >20 ml (or >4.5cm long)
Puberty globally
Timing of pubertal milestones varies across populations and demographics
Boys:
- US boys show early signs of gondarche at 10
- Latino and African American boys maturing ~ ^ months before European American boys
Girls:
- early signs of gondarche at 9-10
- 18% of European American and 40% of African American shwoing Thelarche at 8 years
- this has reduced by 4 yeas in thr past 150 years in early industrialised countires such as the UK
- changes occurring more quickly in newly industrialised countries e.g. China = 4.5 months decrease in past 25 years
But the age of puberty ending has not shifted - longer time in pubertal transition
Neural maturation during adolescence
Brain structure and function undergo substantial chnage
- reductions in gray matter -> synaptic pruning and myelination
Non-linear and region specific:
- hippocampus (HPC) and amygdala (AMG) reaching a mature state earlier than cortical regions
Those regions that show protracted development (association cortex) - remain in a more plastic state
What does this mean?
- more sensitive to environmental input
Adolescent structural brain chnages
Giedd et al(1999): increased in GM volume of the frontal and parietal lobes - peak 10 yo in girls, 12yo in boys -> followed by decreases in these lobes
Gogtay et al (2004): Longitudinal data - loss of G density starting at puberty in the sensorimotor areas, and then spreading over the frontal cortex (rostrally) and the parietal and then temporal cortex (caudally)
- DLPFC loses gray matter last
Synaptic pruning?
Potential alternative: losing gray matter, gaining myelinated white matter?
Prefrontal cortex & adolescence
Executive human brain functions in prefrontal cortex:
- focusing attention
- organising thoughts and problem solving
- forming strategies and planning
- inhibiting inappropriate behaviour and initiating appropriate behaviour
- simultaneously considering multiple streams of information when faced with complex and challenging information
- for seeing and weighing possible consequences of bhevaiour
- shifting/adjusting behaviour when situations change
- modulation of intense emotions
- impulse control and delaying gratification
- ability to balance short-term rewards with long-term goals
- considering future and making predictions
Cogntive development through adolescent years is linked to greater efficiency of cogntive control capacities
One of the last brain regions to fully mature at 25
But - suboptimal choices in behvaiour (e.g. risk taking) is a non-linear chnage in behvaiour that is distinct from childhood to adulthood
If cogntive control and an immature PFC were the basis of behaviour children should look even worsen than adolescents
What behaviours do we associate with adolescent?
Shifts in behaviour
- social relationships
- risk-taking behaviours
- increased emotional reactivity
Social behaviours and the brain
Adolescence is marked by increased social relationships
Also a more complex sense of self
What is the relationhsip between social belonging and exclusion and brain development
The social brain: some of the latest maturing brain regions
Dorsomedial PFC (DmPFC), Temporoparietal junction (TPJ) - inferring mental states
Precuneus - perspective taking and mental imagery
Posterior superior temporal sulcus (PSTC) - face perception
Anterior temporal cortex (ATC) - representing and retrieving social knowledge
Protracted structural development:
- TPJ and dmPFC: decrease form childhood into early 20s
- ATC: critical thickness increases until early childhood
How are social emotions processed?
Guilt, embarrassment, shame and pride = presenting another’s mental state
Fear and disgust don’t:
Burnett et al (2009):
Ppts read sentences describing social or basic emotions
- adolescent recruited the dmPFC > adults
- adults recruited left ATC > adolescents
Adding puberty into the mix:
Goddings et al (2012)
- females 11-13
- pubertal hormones (testosterone, estradiol and dehydroepinandrosterone) related to ATC recruitment during a social emotional processing
- ATC positively correlated with hormone levels regardless of age
- dmPFC negatively correlated woth chronological age regardless of hormone levels
Dissociation between puberty and age-related changes in neural fucntion during adolescence
Mentalizing: understanding others behaviours and actions in terms of underlying mental states
Ven den BOS ET AL (2011): social exchange
Age-related increase TPJ activation when ppts were shown trust
DmPFC recruitment for self-oriented choices (defecting)
Young adolescents engaged dmPFC for reciprocal choices
Social interactions shifting from an egocentric perspective?
The impact of social isolation in adolescence
Whitaker et al (2013)
Early and later adolescent rodents: social isolated
- socially isolated ES rodents remembered drug-associated contextual stimuli quicker than LA rodents
Re-socialisation - neural changes not revered in EA isolated rats
A sensitive period of social isolation and its impact on pathology?
Adolescent bulling linked to Alcohol abuse (Topper et al 2011)
Risk-taking
An action where the outcome is uncertain, and potential consequences can be positive or negative
Reactive risk: combination of poor responses inhibition and increased reward sensitivity
Reasoned risk: strategic and planned - relied on increased cogntive control
Adolescent peak in risk-taking is often associated to and adolescent-specific reponse to their peers
Risk-taking behaviours and the brain
Braams et al (2015) longitudinal sample 8-27 years
Measured brain activity in response to rewards
15-17 years: longitudinal peak in nucleus accumbens (NAcc) in response to rewards
Pubertal developemt linked to NAcc activity in response to awards
Decreased vmPFC activation during risk-taking
- exposure to increasing possible losses
Emotional reactivity
Emotional response to an event or chnages in the environment
Adolescence is a period characterised by liable emotional states and increased in frequency and intensity of emotional reactivity
Peaks during mid-adolescence - heightened sensitivity ton social and emotional chnages
This heightened adolescent emotional reactivity includes increased fluctuations, compared to childhood and adulthood, in both positive and negative emotions
Functional development of the amygdala
Children and adolescents recruit the amygdala where processing emotion from facial expressions
Greater amygdala activity for fearful faces in adolescents and children
Children, but not adults, show greater amygdala recruitment for neutral faces than fearful faces
- the amygdala undergoes refinement over childhood and adelsecne?
Emotional reactivity and the brain
Hare et al (2008)
Exaggerated amygdala activity in reponse to fearful facial expressions relative to children and adults
The extent to which this exaggerated reponse diminishes over time was associated with anxiety
Enhanced amygdala activity in reponse to fearful faces was inversely correlated with PFC activity - a modulatory/control role for higher PFC centres on the Amydala
Psychopathology
The emergence of psychopathology peaks during adolescence
Impulse control disorders: 5-14
Substance-use disorders:13-24
Anxiety disorders:L 5-20
Mood disorders: 13-37
Sz: 13-23
Policy implicaqtions for adolescent as a developmental period
Many adult lega privileges start at 18
But the adoption of adult roles and responsibilities generally occur later
Do laws always protect and empower adolescents?
- safeguarding - minimum age of employment, military service, marriage
- laws in different counties give legal rights and privilidges before 18 years e.g. consulting a doctors without parental consent
- other laws restrict full adult rights beyond 18 years e.g. alcohol
Real world cases
New Zealand 2016
- changing its child protection system - protective duty of individuals 18+ years on leaving care as a result of continued vulnerably
- adolescents are given leaving care grants and local authorities are required to provide housing support and other serviced during a transitional period from 18-25
Japan
- promoting civic engagement-reduced voting age from 20 to 18
- should other laws be reduced for consistency? Or a developmental approach to legalisation that differentiate adolescents from harm (in which the legal age may be higher) relative to participation in empowerment (voting age)
Schooling:
- public education in high-incoming countries mandatory to 14-16 years
- global differences in the average years of education in high-low income countires
- given the increasing years of education that are required to enter thge modern economy - a definition of adolescent that ends at 19 in inconsistent with those views
The finanical burden of lengthened schooling
Countries that have extended mandatory schooling have not has a commensurate increase in the age of family financial support
Positive:
- low income counties: cash transferred to students and families
- reset the balance between the cost of education and foregone income from adolescent employment
Negatives:
- Australia - indivuals aged 16-21 years out of work: less supported government unemployment benefits than older adults
- the benefit is 2/3 of the minimum wage - adolescents can become extremely vulnerable
