The Adolescent Brain Is Different

Sixteen-year-old John and 2 friends go to a club where they get into a verbal argument with 3 members of a rival gang. After receiving a particularly gross insult, John pulls out a handgun and fires 3 shots at one of the gang members. He misses, but one of his shots hits a 15-year-old girl in the head and kills her. John is tried in adult criminal court and is convicted of murder.

Judges and attorneys who deal with such cases have many questions that involve mental health issues. How morally responsible is the adolescent defendant? How likely is he to offend again? How amenable is he to rehabilitation? How will handling this case in a particular way affect other juveniles? Punishment is often seen as having 4 potential purposes: retribution, incapacitation, rehabilitation, and deterrence. Mental health experts potentially have something to say that is relevant to each of these purposes-both at the level of the individual defendant and at the level of developing social policy for handling offending adolescents (Table 1).

Legal background

This past June, the US Supreme Court decided the case Miller v Alabama, in which the Court held 5 to 4 that youths younger than 18 years could not be given mandatory life without parole.¹This decision does leave open the possibility of a life sentence without parole for a youth, but only after a judge or jury determines that such a sentence is suitable in that particular case.

The Miller v Alabama decision is the latest in a line of cases going back 25 years in which the Supreme Court has increasingly limited the situations in which minors may receive the most extreme punishments, based largely on a theory of reduced culpability. In Thompson v Oklahoma, the Supreme Court held that it was unconstitutional to impose the death penalty on defendants who were younger than 16 years when they committed their offenses.2 The basic logic was laid out by Justice Stevens, who wrote for the majority in 1988:

. . . the Court has already endorsed the proposition that less culpability should attach to a crime committed by a juvenile than to a comparable crime committed by an adult. The basis for this conclusion is too obvious to require extended explanation. Inexperience, less education, and less intelligence make the teenager less able to evaluate the consequences of his or her conduct while at the same time he or she is much more apt to be motivated by mere emotion or peer pressure than is an adult. The reasons why juveniles are not trusted with the privileges and responsibilities of an adult also explain why their irresponsible conduct is not as morally reprehensible as that of an adult.^2(p835)

Table 1

Mental health issues in punishing adolescents

In the years since that decision, a good deal of research has put meat on the bones of Justice Stevens' characterization of adolescent behavior and on the neurobiology that underlies it. In the 2005 case Roper v Simmons, the Supreme Court found that the execution of minors was cruel and unusual punishment and thus unconstitutional, basing a reduced culpability analysis on 3 aspects of adolescence: immaturity with impulsivity, vulnerability to adverse environmental factors, and the fact that an adolescent's character is not well formed.^3(pp569-570) In 2010, using much of the reasoning of Roper v Simmons, the Court found it unconstitutional to sentence adolescents to life without parole for crimes less than murder.⁴ In cases involving less serious charges, psychiatric assessments may be used in arguing that a case should be tried in juvenile court-an outcome that usually results in less severe penalties.

Criminal responsibility of adolescents

Because children are typically considered insufficiently responsible, their cases are not heard in adult court, while adults are legally presumed fully responsible. Adolescents lie somewhere in the middle of this continuum.

A successful insanity defense negates criminal responsibility. Adolescents rarely use an insanity defense, in part because the incidence of psychosis is considerably lower in adolescents than in adults, and in part because youths who are so obviously mentally ill as to qualify for an insanity defense are often not waived to adult court. While it is fairly clear that adolescents overall are less blameworthy than adults, it is often unclear in a particular case how much less blameworthy a particular adolescent is. Psychiatrists may be called on to consult in such cases to assist in determining the adolescent's culpability.

Developmental considerationsof adolescent aggression and impulsivity

One metaphor sometimes used in discussing adolescent aggression is that compared with adults, adolescents have their foot on the gas and have inadequate brakes. The literature reveals a number of key findings about adolescent development that are important to keep in mind when evaluating juvenile offenders for the courts.

For most youths, the onset of serious violence is an adolescent phenomenon, with a peak age of onset at around 16.⁵ If a person has not acted violently before age 21, the likelihood he or she will ever do so is quite low.

Serious violent offending (defined as aggravated assault, robbery, gang fights, or rape) is surprisingly common in adolescence: the Surgeon General's report on youth violence noted that 30% to 40% of boys and 16% to 32% of girls had committed a serious violent offense by age 17.⁶

For most youths, offending is limited to adolescence. About 80% of adolescent violent offenders stop offending when they reach adulthood, and fewer than half of those who do continue have an adult career of violence that lasts longer than 2 years.⁶

There is little evidence to suggest that one can accurately predict who will go on to offend as an adult and who will not. Some data suggest that delinquents who continue their criminal behavior into adulthood have different developmental patterns: those who persist in criminal activity tend to have a worsening of impulsiveness and ability to suppress their aggression, rather than the improvement that typically comes with maturation.⁷

Serious violence is typically the end of a developmental progression of offenses that begins with low-level offenses (vandalism and shoplifting), progresses to nonconfron-tational offenses (theft), and then to violent offenses (aggravated assault and rape).⁵ Delinquents do not begin their antisocial activities by shooting someone.

Table 2

Factors to consider in assessing adolescent culpability

Finally, adolescent crime is different from adult crime. Adolescents typically offend in groups, while adults typically offend alone. Also, adolescent crime tends to be more impulsive than adult crime.⁸Adolescent culpability is a complex concept. A number of factors should be assessed in evaluating the criminal responsibility of an adolescent offender (Table 2).⁹

Adolescent immaturity

The area that has received the most attention is adolescent immaturity and impulsivity. Cauffman and Steinberg¹⁰ found that lower levels of psychosocial maturity correlated with more decisions to commit antisocial acts. Moreover, psychosocial maturity was a more significant predictor than age. Considerable research has further refined our views of components of adolescent judgment; such factors as risk-taking, reward-seeking, impulsivity, and self-regulation have been used to argue for mitigation of adolescent culpability.^11,12

Over the past decade, there has also been considerable research on adolescent brain development. The findings are consistent with a biological explanation for the behavioral findings in adolescence and point to an evolving understanding of why adolescents overvalue immediate rewards and lack the impulse control of mature adults.^13-15 These findings show that the limbic system, responsible for emotions, matures before the prefrontal cortex, which is responsible for executive functioning. Furthermore, the tracts between the prefrontal cortex and the limbic system continue to be myelinated through adolescence.

These findings are consistent with the hypothesis that the decrease in impulsivity seen with aging into early adulthood is due to delayed maturation of the prefrontal cortex (the brakes) and its ability to control impulses emanating from the limbic system (the gas). Such findings provide a biological substrate to the argument that adolescents are less mature than adults.

In a particular case, the strongest evidence for impulsivity usually comes from the details of the crime itself. If the crime can be shown to have occurred in the heat of the moment, as in the example given above, impulsivity is clear. If the crime is planned and predatory, the impulsivity argument may not apply. In some cases, historical data from collateral sources (such as reports of persons who know the defendant, previous mental health assessments and treatment, and prior criminal activities) may provide corroborative information regarding the defendant’s impulsivity in other situations.

Environmental circumstances

An adolescent typically has no choice in such matters as what neighborhood to live in; what school to attend; whom to live with; or whether to continue to live in abusive, neglectful, or dangerous circumstances. Also, he is not responsible for the economic circumstances of his family. The Supreme Court has recognized this as a basis for decreased culpability: "[Adolescents'] own vulnerability and comparative lack of control over their immediate surroundings mean juveniles have a greater claim than adults to be forgiven for failing to escape negative influences in their whole environment."³There is strong statistical support linking adolescent crime rates to conditions of socioeconomic deprivation.¹⁶

Ascertaining the socioeconomic background of a juvenile offender can often be done from collateral sources. Assessing the effect of adverse circumstances on an individual defendant is more complex, but there is nevertheless considerable social science data on the effects of factors such as abuse, neglect, and family disruption that the expert may draw on to help justify his conclusions.

Peer group effects

If you want to know how much trouble an adolescent is getting into, ask how much trouble his friends are getting into. Most adolescent offending occurs in groups, and adolescents are especially vulnerable to peer pressure. Gang membership is one of the leading risk factors for predatory violence. Peer group effects are amplified in street subcultures, where it is necessary to appear tough to avoid being seen as weak and therefore vulnerable to attack. Such environments decrease responsibility when the violence, while considered wrong by society, is considered right in the subculture where a youth lives.

The details of the crime, particularly if the crime involved multiple perpetrators, provide evidence as to whether peer group effects were significant. In some cases, there may be characteristics in the defendant’s history that suggest susceptibility to peer pressure as well, such as when an intellectually disabled youth has a history of being easily talked into unwise actions by delinquent peers.

Unfinished character development

We expect that a 15-year-old adolescent imprisoned for life will not be the same person at age 45; the same is not true for someone convicted as an adult whose personality is likely to remain relatively stable. The fact that personality frequently changes from adolescence to adulthood has repeatedly been cited by the Supreme Court as one of the rea-sons why adolescents have lessened responsibility.^1,3,4

Antisocial personality, by DSM convention, cannot be diagnosed until age 18. Psychopathy (a non-DSM diagnosis, but one used in forensic psychiatry to get at the more inter-nal aspects of antisocial personality, such as exploitativeness and severe deficits in empathy and guilt) is an especially worrisome personality type when seen in adolescents. Nevertheless, psychopathy diagnosed in adolescence is not highly predictive of adult psychopathy: the reported correlation of r = 0.31, while significant, is not strong enough to account for enough of the variance to be very useful in sentencing an individual delinquent.¹⁷In addition to the clinical interview, a variety of personality tests can be used to buttress conclusions about the defendant's present personality characteristics.

Mental illness

It is well established that among delinquent youths, the rate of mental disorders across the entire range of diagnoses is high.^18,19 Excluding conduct disorders, more than 60% of incarcerated juveniles report at least one disorder, about triple the rate in the general population, and more than 40% report more than one disorder. In most cases, delinquent behavior is not thought to be "caused" by mental illness, but a mental disorder likely magnifies the effects of other factors relevant to reducing culpability through such pathways as further impairing judgment and slowing consolidation of a healthy identity. When an evaluation reveals a mental illness, the youth's amenability to treatment has implications for rehabilitation.

Attitudes toward adolescence

Attitudes toward juvenile offending range from "do the crime, do the time," with its implication for full adult punishment, to "they’re just kids"-a response that elicits more parental feelings of helping offenders not repeat their problematic behavior. Reacting to adolescents as though they are adults brings with it the ready set of attitudes that we apply to adult offenders. If we see adolescents as different from adults, but also as different from children, then we will use, or have to find, a different set of attitudes.

Attorneys often ask experts to testify "about the adolescent brain" in sentencing hearings. Why does such testimony have power? The data showing that adolescents are more impulsive come from studies of behavior, not imaging studies. But the neuroimaging data indicate that the adolescent brain is different, which carries with it an implication that the reactive attitudes that we have toward adults should not apply.

Conclusion

Assessments of partial culpability of adolescents are difficult in individual cases; however, the courts are moving away from mandatory sentencing to individual determinations, even for the most heinous crimes. These individual determinations can frequently be assisted by psychiatrists, because they have an ever-increasing database of behavioral and neurobiological understanding on which to base their opinions.

References:

References

1.

Miller v Alabama,

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2.

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3.

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