Adolescence, Alcohol and Brain Development What is the impact on well-being and learning?

1. Adolescence, Alcohol and Brain DevelopmentWhat is the impact on well-being and learning? Jason White Professor of Addiction Studies and Head in the Discipline of Pharmacology, University of Adelaide and Director of Treatment Services for Drug and Alcohol Services, South Australia.

2. Contents • Adolescence and the brain • Short-term effects of alcohol on the adolescent • Long-term effects of adolescent alcohol consumption

3. Adolescence and the Brain

4. Characteristics of adolescent behaviour • seeking novel experiences • exploring new things • high levels of sensation-seeking • risk taking • high peer social interaction • persistence of play behaviour

5. Function of Adolescence • Time of learning about adult ways • Establishing good social skills • Exploring options, some of which will continue into adult life

6. Brain Maturation Different parts of the brain mature at different periods of development - vision related areas by age 5 - language by age 13 • Full brain development does not occur until mid 20’s Therefore, while the adolescent period of physical development is from 12-18 years, based on brain maturation it extends to about 25 years of age.

7. Brain Maturation (cont.) • In adolescents many brain areas are fully developed, but others are not. Consequences: - some aspects of behaviour are adult-like e.g. many physical and mental capabilities - but some mental functions are not at adult level

8. Adolescence and Brain Immaturity • The last brain structures to fully mature are the areas of the cortex related to so-called executive functions: - decision making - inhibition of behaviour - selective attention - problem solving and reasoning

10. Adolescence and Brain Immaturity • Differences between adult and adolescent behaviour can be largely explained by the immaturity of these parts of the brain • By age 25 these areas of the brain will have matured and the behaviour will be that of an adult (but there are still individual differences in executive functioning between adults)

11. Some Consequences of Adolescent Brain Immaturity • Greater risk taking (poor inhibition) • Failure to think before acting (e.g. diving into water of unknown depth) • Choosing a high risk over lower risk alternatives (e.g. accepting a ride from a driver who has been drinking) • Failure to correct risky behaviour (e.g. continuing argument as it escalates toward violence) • Increased expression of emotion • Emotional areas of the brain are fully developed, but the areas that control emotionality are not. • Failure to show adult levels of reasoning and judgment

12. Short Term Effects of Alcohol

13. Alcohol as a Drug • Like other drugs, alcohol produces its effects by altering the actions of neurotransmitters • Alcohol modifies the action of two major neurotransmitters: • GABA • glutamate • These neurotransmitters are found throughout the brain and hence alcohol has very widespread effects on behaviour

15. Alcohol as a Drug (cont) Indirectly, alcohol stimulates two other neurotransmitters that are important in the development of addiction:  dopamine  -endorphin

16. Alcohol Intoxication • Impairment of general abilities • - impaired vision • - slow response • - impaired thinking • - inability to concentrate • - poor coordination

17. Alcohol Intoxication • Increased risk taking • - ignore long-term consequences of behaviour • Mood changes • - positive mood when BAC rising • - depressed mood when BAC falling

18. The Alcohol Intoxicated Adolescent Combined effects of - Impairment of general abilities - senses - speed of reaction, coordination - thinking, concentration • Increased risk taking in person with poorly developed inhibitory control over behaviour • Alcohol-induced mood changes in person with poor control over mood

19. The Alcohol Intoxicated Adolescent Consequences include increased probability of - accidents - violence - suicide - risky sexual behaviour

20. Different Effects in Adults and Adolescents • For a given amount of alcohol, adolescents are more susceptible than adults to some effects, but less susceptible to others. • Importantly, they are more susceptible to effects related to learning and memory (e.g. the phenomenon of blackout). • They are less susceptible to the sedation produced by alcohol.

21. Differential Effects : Blackouts - complete absence of memory with no possibility of retrieval - results from effects of high alcohol concentrations on brain centres related to memory (especially hippocampus) - uncommon in adults, but relatively common among adolescents (e.g. 10% in last 2 weeks) - consistent with greater susceptibility of adolescent memory centres to disruptive effects of alcohol

22. Differential Effects : Sedation • Less sedation means that adolescents can keep drinking longer without falling asleep. • Result is higher consumption of alcohol than adults. - Brain mechanism not known

23. Post Intoxication Effects “Hangover” can produce significant impairment in normal functioning (e.g. ability to concentrate, memory, speed of responding). It is due to a combination of - alcohol-induced sleep changes - dehydration (hormone changes) - alcohol-induced changes in neurotransmitters - alcohol withdrawal

24. Long-term Effects of Adolescent Alcohol Consumption

25. Types of evidence (1) • Correlations between adolescent binge drinking and later behaviour or brain function

26. Compared to those who don’t binge drink as adolescents, those who do perform worse on: • memory tasks • problem solving • visual and spatial skills • In addition, the pattern of brain activity while performing these tasks is different.

27. Compared to those who don’t binge drink as adolescents, those who do are more likely to: • Develop an alcohol problem • Develop another substance abuse problem • Develop a mental health problem • Be involved in criminality • Have academic difficulties • Be financially less well off

28. And…… The earlier an adolescent starts binge drinking, the worse the problems of alcohol and other substance use, mental health, criminality, etc.

29. Causation • Alcohol may cause irreversible damage to the adolescent brain resulting in a poorly functioning adult brain, susceptible to the various problems. This is consistent with evidence that damage to areas controlling executive functions predisposes to a range of mental health and related problems.

30. But,…... • Adolescents who binge drink may be different in ways that predispose to the various problems ie, those with a predispostion to drinking problems, mental health problems etc may also be more likely to binge drink as adolescents.

31. Types of evidence (2) Animal studies - easier to demonstrate causation • necessary if we want to understand changes in the brain But, - need to make sure of relevance to humans

32. Brain Development Different brain areas develop at different times during maturation - Roughly from back of brain to front - Executive functions (planning, decision- making, impulse control etc.) occurs in frontal regions

33. Normal brain development : stages of development • As an area matures it goes through three stages over a period of years: • Proliferation of pathways • Pruning of these pathways • Myelination (white matter)

35. Normal brain development : function of different stages of development • Proliferation of pathways • - makes the brain versatile and able to adapt to different environments • Pruning of these pathways • - with experience the unused pathways are eliminated, narrowing the options for behaviour • Myelination (white matter) • - makes the remaining pathways faster and more efficient • As a result brain has become adapted to environment and efficient in functioning, but is less able to change in future.

36. Effects of alcohol on developing brain • Affects two of the three stages of development: • Inhibits growth of neurons • Decreases myelination • Alcohol can also cause death of nerve cells • As a result, alcohol has greater effect on developing areas on the brain compared to those already fully developed.

37. Evidence for effects of alcohol on adolescent brain 1. The adolescent brain is more susceptible to damage than the adult brain 2. Alcohol exposure during adolescence can induce changes that persist into adulthood i.e. damage during adolescence may be permanent. 3. Some regions of the brain (those still developing) are damaged to a greater extent in adolescents than adults – includes areas related to executive functions

39. These results provide direct evidence that exposure to alcohol at intoxicating levels during adolescence can produce permanent brain changes and that developing brain regions (such as those related to executive functions) are most susceptible. Significant implications if translates to humans

40. Conclusions • The adolescent brain is undeveloped in areas related to decision-making, inhibition and other ‘executive’ functions • As a result, alcohol intoxication has particularly strong effects on adolescent behaviour leading to a range of adverse outcomes. • The evidence to data is suggestive, but not conclusive with regard to permanent brain changes produced by adolescent binge drinking.

41. Conclusions We do know that • Those who binge drink, particularly early in adolescence, have worse outcomes in a variety of aspects of adult life. • This may occur, at least in part, because alcohol interrupts the normal processes of brain maturation.