Adolescent Brain Development and Medical Decision-making

Cassandra C., a 17-year-old from Windsor Locks, Connecticut, diagnosed with Hodgkin’s lymphoma, was estimated to have an 85% chance of survival with standard treatment involving chemotherapy. After repeatedly failing to show up for medical appointments, Cassandra and her mother refused to consent to treatment with chemotherapy. The state’s child protection agency was involved, and Cassandra was ordered to present for treatment. However, after her second chemotherapy treatment, Cassandra ran away from home briefly to avoid being forced to undergo further chemotherapy. After returning home, she was placed in the hospital to ensure that she would receive treatment. Both she and her mother persisted in their refusal to consent, claiming that chemotherapy was poison. Cassandra and her mother preferred to explore alternative, less toxic therapies and argued that the quality of her life was more important than how long she lived. Approximately 6 months shy of her 18th birthday, an age at which she would attain the legal right to refuse life-sustaining therapy, Cassandra and her mother, with the aid of a lawyer, claimed that she was a mature minor and that her right to make the decision to refuse treatment should be respected. The Connecticut Supreme Court disagreed, supporting the ruling of a lower court and finding that she was not mature on the basis of any standard and ordering her to submit to treatment.¹ 

Parents are generally granted the authority to make medical decisions on behalf of minor children, including adolescents, and they are granted significant discretion as long as their choices do not place the child at significant risk of serious harm compared with other alternatives. In situations in which a parent’s refusal does place a child at significant risk of serious harm, in which action is necessary and likely to prevent the harm and efforts to convince the parent to pursue the recommended route have failed, a health care provider may either notify the state child protection agency or seek a court order to compel treatment of the child over parental objections.²  When the patient is an adolescent, however, the decision-making process may become complicated. If the adolescent is felt to be sufficiently mature, providers and legal authorities may be inclined to respect the adolescent’s wishes, even in situations in which the health or life of the adolescent is at significant risk and a parental refusal would generally be challenged as medical neglect.

There are 3 situations in which a minor possesses the legal authority to make decisions regarding his or her health care.³  First, state laws designate certain minors as emancipated and grant these emancipated minors the right to make decisions, including health care decisions. Emancipated minors may also refuse medical care. Although emancipated minor statutes vary from state to state, most states recognize minors as emancipated if they are married, economically self-supporting and not living at home, or on active-duty status in the armed services. Second, most states designate condition-specific exceptions to consent laws whereby adolescents, usually of a certain age, are granted the authority to provide informed consent. These condition-specific areas typically include the diagnosis and treatment of sexually transmitted diseases, pregnancy-related care, and the treatment of substance abuse. It is important to note that these condition-specific exceptions exist primarily for public health reasons and not because legislatures believe that minors possess full capacity to make decisions related to those health conditions. Finally, most states have some mechanism whereby adolescents can be granted “mature minor” status. There is significant variation among states regarding mature minor determinations: some states allow medical professionals to make a mature minor determination; others require a judicial determination, and states differ regarding the minimum age at which such a finding can be made.

Cassandra C. was not emancipated and had not been designated a mature minor. The legal authority to make decisions about her medical care fell to her mother, who refused to grant permission for medical treatment of her cancer. If Cassandra were significantly younger, say <12 or 13, the standard approach would be to seek state intervention to authorize treatment on the grounds that her parent’s refusal to grant permission for treatment placed her at significant risk of serious harm compared with the harms of the medical interventions being recommended. However, Cassandra was within one year of attaining the age of majority, and whether her decision should be respected and she treated as a mature minor remains an important question.

When adults refuse potentially lifesaving therapies, they are generally assumed to possess the capacity to make that decision. The ethical basis for this stance rests in the principle of respect for autonomy. Unless an adult is found to lack capacity, their decision is respected, even if it results in death. Adolescents, on the other hand, are assumed to lack capacity unless they can demonstrate otherwise. If an adolescent can successfully exhibit adult-like decision-making capacity, however, the ethical principle of autonomy would seem to require that his or her decision be respected. As a general rule, establishing capacity to make a health care decision requires some combination of the following⁴ :

• the ability to evidence and communicate a choice;

• an understanding of the information and facts relevant to the choice;

• an appreciation of the situation and the consequences of the decision; and

• the ability to assess the information in a rational way.

Health care providers and legal authorities have used these criteria to establish whether a given adolescent should be treated like an adult regarding decision-making authority. These determinations are influenced by empirical studies that suggest that by the age of 14, the ability of adolescents to make rational and reasonable health care decisions approximates that of adults.^5–10  Perhaps the most widely cited of these studies was performed by Weithorn and Campbell,¹¹  who used hypothetical treatment dilemmas and a scoring system designed to rate subject responses in terms of each of 4 tests of competency (evidence of choice, reasonable outcome of choice, understanding, and a choice derived from rational reasoning) at each of 4 age levels (9, 14, 18, and 21 years). Employing a rigorous methodology, these investigators demonstrated that although 9-year-olds appeared less competent than adults, 14-year-olds did not differ significantly from 18- and 21-year-olds in terms of their ability to express reasonable preferences regarding medical treatment. These authors (like many of those who cite their work) concluded that the findings did not support the denial of the right to self-determination in treatment situations on the basis of presumed incapacity and that most adolescents >13 years of age possessed the capacity to make such decisions.

Bioethicists have been persuaded by these early empirical explorations of developmental ability.^12–16  For example, Weir and Peters¹⁶  argued as follows:

The conclusion that at least some adolescents are capable of making adult-like decisions is based on an underlying model of decision-making capacity that is focused on assessment of the adolescent’s rational faculties: primarily assessments of understanding and reasoning. Using those criteria, many adolescents older than the age of 14 years appear capable of making rational decisions that approximate those of adults and seem capable of fulfilling the requirements of informed consent. Those familiar with adolescent behavior and decision-making in real-life situations, however, have pointed out that this formulation does not seem complete. Although adolescents, even older adolescents, have the ability to make adult-level decisions, they frequently do not exercise that ability optimally, leading to decisions that differ from those that a typical adult would make. The emphasis on intellectual and rational capacity appears to ignore other elements of decision-making that remain deficient in the adolescent compared with the adult.¹⁷  For example, adolescents are more affected by the influence of peers, less future oriented, more impulsive, and differ in their assessment of risks and rewards compared with adults.¹⁸  Psychosocial factors appear to interact in important ways with the cognitive elements of decision-making.¹⁹  This would suggest that a model of capacity assessment that rests solely on the adolescent’s ability to understand and reason is incomplete. More recent neuroanatomical and neuropsychiatric evidence suggests that this traditional understanding of adolescent decision-making capacity is inadequate.

Decision-making appears to rely on dual systems within the brain: a socioemotional system composed largely of limbic and paralimbic structures and a cognitive-control system composed of prefrontal and parietal cortical structures.^20,21  The socioemotional system tends to involve rapid, automatic processing that is often reactive, intuitive, and unconscious, picking up patterns before an individual may be consciously aware of them and motivating behavior change through feelings and autonomic responses. The cognitive-control system, on the other hand, tends to be consciously controlled, volitional, deliberate, reasoned, analytic, and reflective and requires more time and a conscious effort.^22,23  Both systems are essential for good decision-making to occur.

The development and integration of these 2 systems have not fully matured in the adolescent brain. Final brain maturation begins during adolescence and tends to occur from back to front,²⁴  with the prefrontal cortex (that part of the brain associated with high-level reasoning, executive function, weighing of consequences, planning, organization, emotional regulation, and rational decision-making) being among the last to mature. This process of maturation occurs ∼1 year earlier in girls than boys but extends well into the 20s for both sexs.²⁵  During this period of rapid change, the adolescent brain is different from the mature adult brain, differences that help explain why adolescent decision-making often differs from that of mature adults.

The socioemotional and cognitive-control systems mature along different trajectories, with the socioemotional system maturing around the time of puberty and the cognitive-control system maturing in the mid to late 20s. Integration between the 2 systems (which may be important for the cognitive-control system to exert control over the socioemotional system) also matures in the 20s. Thus, not only has the part of the brain associated with executive control and reasoning not fully matured during adolescence, but an imbalance of sorts develops, with the maturation of the socioemotional areas of the brain occurring earlier than the cognitive-control system. In other words, those areas of the brain responsible for emotion, arousal, orientation to rewards, and sensation-seeking are fully engaged at a time when the regulatory functions of the prefrontal cortex are not yet fully matured. Although their brains may be capable of adult-like decision-making, adolescents may have difficulty engaging the cooler, more rational parts of their brains under certain conditions. The relatively automatic responses of the limbic system may overpower the response inhibition function of the prefrontal cortex, or, put another way, the adolescent’s accelerator (socioemotional system) may overpower the adolescent’s brakes (cognitive-control system).^26,27 

This relative imbalance between the socioemotional and cognitive areas of the brain (combined with still-developing integration between the 2) manifests in several well-described behavioral implications during adolescence: the ability to regulate and understand emotions remains underdeveloped, susceptibility to peer influence is greater, the ability to delay rewards is limited, and adolescents and young adults are more likely than adults to engage in a variety of risky behaviors (binge drinking, cigarette smoking, casual sex, violent or criminal behavior, and dangerous driving behaviors).²⁸  The increased risk-taking behavior seen among adolescents does not appear to be the result of deficits in logic or reasoning. Adolescents are similar to adults in terms of their ability to perceive risk, evaluate risk, and estimate their vulnerability to it.²⁹  However, they may weigh risks and benefits differently under certain conditions and react more impulsively, perhaps ignoring that little voice warning them of danger.^29,30  In addition, adolescents may consider some forms of risk in certain contexts to represent a positive thing (offering an immediate reward in terms of excitement or a way to maintain or enhance social status), whereas an adult might perceive the same risk as a negative thing (focusing more on the potential future losses). Adolescents appear to focus more on the immediate benefits (a socioemotional brain system function) than the future costs of risky behaviors (a cognitive-control brain system function), a finding that is exacerbated in the presence of peers.³¹ 

Another way of thinking about the adolescent brain is that adolescents, to varying degrees, experience what might be called prefrontal cortex deficit disorder, a developmental condition marked by those characteristics commonly associated with adolescence: impulsiveness; inflexibility; aggressiveness; recklessness; emotional volatility; risk-taking with less sensitivity to risks than to possible short-term rewards, excitement, and arousal; reactivity to stress; vulnerability to peer pressure; tendency to underestimate long-term consequences; and tendency to overlook alternatives.

Although the adolescent brain, as early as age 14, is good at decision-making tasks, it may become less so in emotionally charged situations or when experiencing pressure (including peer pressure). Adolescents are sensitive to environmental cues, affective elements, rewards and punishments, and the presence of peers, and have a more difficult time resisting these pressures than a more fully mature individual. Adults are often more able than adolescents to resist these social and emotional influences and focus on long-term goals rather than short-term rewards.²³  Finally, unlike adults, adolescents do not appear to enhance cognitive performance when the stakes of a decision are high.³² 

This pattern of brain development makes sense from an evolutionary perspective.³³  The delayed maturation of the cognitive-control system allows adolescents a longer period of time to learn and experience before finalizing connections within the brain. Adolescence is a time when a person begins to move from the safety of home to a complex outside world. This requires adaptability and a willingness to take risk. The sensation-seeking and risk-taking that results from a relatively immature cognitive-control system leads to enhanced learning and strengthens social connections. Having individuals with an adolescent brain in the kind of small communities and tribes that composed the world hundreds of years ago would also be useful. Adults in their 30s and 40s, with brains that become much more risk averse and less inclined to explore, are far less likely than adolescents to venture beyond the boundaries of camp to search for resources, hunt for food, assess for dangers and enemies, and go to war to defend the tribe.

The point of the previous discussion is not that one brain system is better or more important than the other but that both are essential to good decision-making. Decision-making that occurs in the presence of damage to one or the other system is commonly flawed in significant ways.^34,35  Despite the fact that teenagers are capable of rational and intelligent decision-making, it is unwise to conclude that they always make decisions using the same cognitive processes that adults do. Adolescents, even those at the age of majority, have a relatively underdeveloped prefrontal cortex, particularly in those regions concerned with functions essential to good decision-making. The result is a situation in which the prefrontal cortex is often not fully engaged, allowing the more fully matured, but more reactive, socioemotional system of the brain to dominate, particularly under conditions of high stress or emotion, peer presence or pressure, and perceived short-term benefit. The ability to think about the future, plan ahead, and anticipate future consequences increases gradually throughout adolescence but does not peak until well into the 20s.

What are the implications of these findings for decision-making in the clinical environment? These findings do not suggest that adolescents lack the capacity to make all decisions or that they should not be involved with discussions about their preferences in the health care setting. These findings should, however, raise serious concerns when an adolescent makes a decision that appears to pose a significant threat to his or her future well-being.

It remains important to respect adolescents and recognize their developing capacity. Adolescents should be involved in discussions about their health care and should be offered the opportunity to participate in discussions and voice their feelings, opinions, concerns, and fears. Their developing capacity should be honored, and they should be provided with reasonable opportunities to make choices and have those choices respected. In many cases, a successful therapeutic plan requires the adolescent patient to cooperate, and involving their participation and respecting their views are important components of a therapeutic alliance. Any use of force requires strong justification.

But the desire to respect adolescent decisions must be coupled with the recognition that decision-making, even of mature adolescents, may occasionally be flawed. Health care providers should recognize that under certain conditions (stress, high emotion) or in certain situations (in which the presence or pressure of peers, family members, or spiritual community members may play a role), adolescent decision-making is often less than optimal (and may be more a reflection of what others want than what they want).^36–38  In those cases, adolescents may require limits on the kinds of decisions they are allowed to make. As a general rule, minors should not be permitted to refuse lifesaving interventions that offer a reasonable probability of success. Cassandra C., a 17-year-old with an otherwise good prognosis, wished to forgo chemotherapy for her cancer, a decision that would almost certainly result in her death. We wouldn’t allow a parent to make that decision on behalf of a 7-year-old or a 17-year-old, and we shouldn’t allow a 17-year-old to make that decision for herself. The bottom line is that if a parental decision to refuse a medical intervention on the adolescent’s behalf would be challenged (because it places the adolescent at significant risk of serious harm compared with rejected alternatives), we should be reluctant to allow the adolescent to make it.³⁹ 

One might ask why these implications do not apply to those adolescents who are over the age of majority. Cassandra C. was months shy of her 18th birthday, and there were those who argued that her proximity to the age of majority should have led to her being treated like a mature minor. The current age of majority (18–21 years of age depending on the state) is not clearly supported by empirical data, at least for some decisions. It may well be that the age of majority should be reconsidered; however, such a discussion is beyond the scope of this article. For purposes of this article, however, the data establish fairly clearly that most adolescents younger than the legal age of majority have not yet attained a level of brain maturation that justifies treating them like adults with respect to significant, potentially life-altering health care decisions.