Psychiatric and Substance Use Disorders in Transitioning Adolescents and Young Adults

Overview

The period of transition from childhood to adulthood known as transitioning adolescents and young adults (TAY; age 16–26 years) has received increased attention. TAY are navigating the potentially perilous developmental years while leaving childhood and entering adulthood, where more adult-like challenges are faced without having mastered much-needed tools and cognitive abilities. A number of critical developmental steps occur during this transition that reflect changing neurobiology, the tasks of separation and individuation, and the influences of pre-existing and concurrent mental health and substance use issues. Parents with TAY sustain high burdens of care, particularly for those with common unmet needs. In fact, psychopathology and substance abuse are the leading cause of disability worldwide and they constitute 45% of the disease burden in TAY. A disconnect in the system of care for TAY often exists. Child psychiatrists are increasingly asked to evaluate or provide care for youth as they enter independent living settings (such as college) and adult psychiatrists are increasingly called upon to evaluate and treat adolescents and young adults for psychopathology and substance abuse. Thus, psychiatric practitioners must be prepared to address the major concerns and opportunities surrounding TAY: specifically, early recognition of the signs and symptoms, identification of risk and protective factors, and timely and effective interventions for psychopathology and substance abuse.

Salient Neurobiology of Transitioning Adolescents and Young Adults

Brain development continues throughout adolescence and young adulthood. Developmental neurobiology offers insights into limitations in decision-making, impulsivity, risk-taking, and emotional regulation that may be related to the developing brain and into behaviors manifested in TAY. Casey and colleagues and Giedd and associates highlighted that the limbic areas develop early in adolescence and govern reward-based drives. In contrast, areas of the frontal lobes that are related to processing, inhibiting, decision-making, and shifting continue to develop for several more years—often into TAY years. The incongruity between the maturation of the limbic (emotional, reward) and executive operations (frontal, inhibition) may underpin a heightened risk for excess emotionality, reward-seeking, and poor judgment. These observations may explain why TAY are particularly susceptible to the manifestation of psychopathology and substance use disorders (SUD).

Central to addiction, disruption in the normal circuitry in the reward and inhibition pathways of the brain appears operant. Disruption in signaling between the executive centers (frontal lobes, inhibition-based) and emotional/motivation centers (hippocampal formation, amygdala; reward-based) is seen with addiction, and may even pre-date some of the changes associated with addiction. For instance, disruption in frontal activity dampens inhibitions, as well as a number of executive functions (planning, organization, motivation) that are critical to the functioning of TAY. Likewise, the limbic regions (the hippocampus, amygdala, and others) that develop relatively early in TAY lives are involved in reward, emotion, and risk-taking. It may be that many of these regions related to addiction are affected by, or have a delay in maturation associated with specific psychiatric disorders (e.g., ADHD or bipolar disorder) known to predispose to later SUD. For instance, the lack of inhibition of limbic or emotional regions may result in disinhibited behavior, excess reward-seeking (substance use, unprotected sex), and other high-risk behaviors that may culminate in other addictive behaviors.

Epidemiology

Psychopathology may emerge in TAY or may be present in childhood and persist ( Figure 70-1 ). Accumulating data suggest that a combination of the two explains the high prevalence rates of psychopathology and SUD in TAY ( Box 70-1 ). For instance, one of the most studied childhood disorders, attention-deficit/hyperactivity disorder (ADHD), which begins in early childhood, affects 6%–9% of youth. Childhood ADHD persists into adolescence in 75% of cases and into adulthood in approximately one-half of cases (for review see Wilens and Spencer ). Many of the manifestations of ADHD occur in TAY and include academic, occupational, and interpersonal dysfunction —critical areas for TAY who are beginning to live independently and start working and/or attending college. Unfortunately, insufficient attention to this age range is associated with low rates of adherence to treatment, with subsequent return of ADHD symptoms, with functional impairment, and with emergence of complications/co-morbidities of the disorder (e.g., academic failure, cigarette smoking).

Anxiety and post-traumatic stress disorder (PTSD) are recognized as having their onset in childhood and young adulthood with persistence into adulthood. Using data from the National Comorbidity Survey Replication that surveyed 9,282 respondents, Kessler and co-workers found that the median age of onset for anxiety disorders was 11 years of age. A more recent survey, conducted by Vaingankar and associates reported on 6,616 respondents and noted that the mean age of onset for generalized anxiety disorder was 20 years of age. Giaconia and colleagues found that in a community sample of adolescents, 6.3% met criteria for PTSD. Furthermore, the peak period of risk for developing PTSD was 16–17 years, with almost one-third of the sample developing the disorder by age 14 years. Several studies have found that early-onset anxiety disorders are associated with a greater severity and chronicity compared to adult-onset disorders. Moreover, persistent childhood-onset anxiety in TAY appears to increase the likelihood for the development of subsequent psychiatric co-morbidity and greater familial loading.

Age of onset of obsessive-compulsive disorder (OCD) has revealed differences in the neurobiology and genetics of the disorder. For example, early age of onset is associated with higher rates of co-morbid tic disorders and a higher frequency of tic-like compulsions. The average age of onset for OCD is in the TAY years. For example, based on a national mental health survey, Vaingankar and associates found that the median age of onset for OCD was 19 years of age. Similarly, Millet and colleagues collected data from 617 patients with OCD and found that the majority had their onset between the ages of 11 to 25 years. Furthermore, they found that the number of obsessions and compulsions was significantly greater in the group with an earlier age of onset (P<0.001). Likewise, Delorme and co-workers studied 161 patients with OCD and divided them among early-onset and late-onset OCD. The majority (88%) of their sample fell into the early-onset OCD group, mean age of onset of 11 years (SD = ± 4 years), which was correlated with a higher fre­quency of Tourette's syndrome and an increased family history of OCD.

Mood disorders, such as dysthymia and major depressive disorder (MDD), are common and highly disabling in TAY. In the National Comorbidity Survey, Kessler and colleagues found that the lifetime prevalence of minor depression in 15–18 year olds was 11% and that of MDD was 14%. Zisook and colleagues reported that over half of all cases of depression had their onset during childhood or TAY years. Consistent with the work of Zisook and colleagues, others have shown an elevated risk for mood disorders that begins in the early teens and rises in a linear fashion throughout the TAY years, with rates of up to 25% by late adolescence. Longitudinally-derived data indicate that having a mood disorder or prominent mood dysregulation in childhood increases the likelihood for a mood disorder in adolescence and adulthood. It is not surprising then that the rates of depression reported during the TAY years approximates those in adult samples, suggesting that the peak onset of the disorders are during the TAY years.

Mood disorders developing in TAY predict a wide variety of negative outcomes in adulthood, including unemployment, serious social and educational impairment, and obesity. Furthermore, early-onset mood disorders are linked with other mental health problems in adults, such as anxiety disorders and SUDs. Of greater concern, depression in TAY is a major risk factor for suicide, a leading cause of death for this age range, with more than half of adolescent suicide victims, for instance, reporting depressive symptoms at the time of death.

Despite an early belief in the absence of cyclical mood disorder during childhood, the manic behavior, poor judgment, and severe mood dysregulation of bipolar disorder can also begin in youth and worsen during TAY years. Juvenile bipolar disorder affects between 1% to 4% of the pediatric population, with up to one-fifth of psychiatrically-referred children and adolescent outpatients manifesting bipolar disorder. Furthermore, pediatric-onset bipolar disorder is highly co-morbid with SUD, with internalizing and externalizing psychopathology, and is remarkably stable over time.

An emerging literature has shown that the majority of adults with bipolar disorder develop their disorder in childhood and the TAY years, and at least one-third of adults with bipolar disorder have the onset of the disorder before the age of 12 years. For example, Perlis and associates reported on 1,469 subjects from a large multicenter systematic treatment enhancement program for bipolar disorder (STEP-BD) and found that the mean age of onset of bipolar disorder was 16.7 years. Not only are early or TAY-onset cases common but also data suggest they are more complicated in their adult form. For example, adults with earlier-onset bipolar disorder have been reported to be at higher risk for other neuropsychiatric disorders, for more psychiatric and SUD co-morbidity, for less lithium responsiveness, and for more mixed presentations.

Eating disorders are recognized as among the most complex and disabling of psychiatric disorders. Research indicates that the heterogeneous group of eating disorders (including bulimia, anorexia, binge eating) often emerge during early adolescence and show a rapid increase in incidence during the transitional years. For instance, Hudson and co-workers in the National Comorbidity Survey Replication (n = 2,980) reported a steep increase in the cumulative prevalence of eating disorders during the TAY years. From a prospective analysis of 8594 women, Field and colleagues found that the prevalence of eating disorders increased substantially with age until early adulthood, with up to 22% of the sample manifesting an eating disorder at one point. Furthermore, Stice and associates examined the peak periods for onset of the various eating disorders. They found that peak periods for onset were between 17 and 18 years for bulimia nervosa and binge-eating disorder, and between 18 and 20 years for purging disorder. Given the prevalence and chronicity of eating disorders in TAY, these data support the importance of identifying and understanding the diagnosis and treatment of these disorders close to their onset.

Schizophrenia is recognized as one of the most debilitating psychiatric disorders, with some studies suggesting that early-onset schizophrenia (i.e., onset before age 18 years) may represent a more severe variant of the disorder, with studies reporting lower psychosocial functioning and worse long-term outcomes.

Early-onset schizophrenia has its beginning in the TAY years. In an older Swedish family study of 270 schizophrenic probands, Sham and associates found that for both men and women there was a rapid increase in the onset of schizophrenia in the late teens and early twenties followed by a rapid decline in the late twenties. Similar results were found by Hafner and co-workers who studied 267 schizophrenic patients and found that the onset of the disorder showed an early and steep increase in adolescents until the age of 25 years, with 47% of women and 62% of men having their first symptoms of schizophrenia before the age of 25 years.

Early identification and intervention of at-risk samples may result in a reduction of the ultimate expression of the disorder. For instance, one recent study focused on use of omega-3 as a way to prevent early psychosis in at-risk populations. A randomized, double-blind, placebo-controlled trial conducted by Amminger and associates assessed 81 individuals at ultra-high risk of a psychotic disorder. Of these, 41 received 1.2 g/day of omega-3 for 12 weeks while 40 controls received placebo followed by a 40-week monitoring period. By the end of the study 2 of the 41 individuals (4.9%) in the omega-3 group and 11 of the 40 (27.5%) in the placebo group developed a psychotic disorder (P = 0.007). Omega-3 improved overall functioning compared to placebo and also reduced positive symptoms (P = 0.01), negative symptoms (P = 0.02), and general symptoms (P = 0.01).

Autism spectrum disorder (ASD) consists of a group of related complex and chronic neurodevelopment disorders: autistic disorder, Asperger disorder, and pervasive developmental disorder not otherwise specified, that are generally characterized by a variable presentation of problems with socialization, communication, and behavior. Symptoms of ASD can be identified in children as young as 18 months, with screening recommended to begin at 24 months for all children. In years past, the overall prevalence of autism was reported at 2–4 per 10,000 children ; however, more recent studies have indicated that 1%–2% of children and adolescents meet criteria for ASD. Data derived from the National Survey of Children's Health (NSCH), conducted by the Centers for Disease Control and Preventions National Center for Health Statistics, found that the prevalence of ASD among children aged 6–17 increased from 1.2% in 2007 to 2.0% in 2011–2012.

ASDs are typically considered a childhood diagnosis; however, most have significant functional impairment throughout their TAY and later adult years. Numerous studies have shown that ASDs are persistent, indicating that although the severity of autism may decline during the adult period, social functioning is worse than in younger adulthood. Furthermore, the majority of the observed increase in prevalence appears to be accounted for by adolescent boys ages 14–17.

Limited research on TAY with autism exists. Longitudinally, derived data in individuals with ASDs, followed from (mean) age 7 to 29 years having IQs > 50, indicated a range of outcomes: 12% were rated as “Very Good” outcome; 10% were rated as “Good” and 19% as “Fair outcome”. The majority was rated as having a “Poor” (46%) or “Very Poor” (12%) outcome that often required extensive family involvement and/or hospital level of care. The majority of individuals remained dependent on their families or other supports. Few had permanent jobs, lived alone, or had close friends. Stereotyped behaviors or interests frequently persisted into adulthood and their communication was generally impaired. Those with an IQ > 70 had a significantly better outcome than those with an IQ < 70.

The impairments associated with ASDs in children and adolescents may be accentuated by the high rate of co-morbidty. Simonoff and co-workers examined 112 children and adolescents with ASD (mean age of 11.5 years) and found that 70% had at least one co-morbid disorder and 41% had two or more. De Bruin and colleagues studied 92 children with ASD (age 6–12 years) and found that 81% presented with at least one co-morbid psychiatric disorder. The children with co-morbidity showed more deficits in social communication than those with only ASD.

The TAY years seem to represent a previously unrecognized but critical window for improving skills for those with ASD. Taylor and Seltzer studied 242 youths who were about to exit the school system; they found that there was an overall improvement of autism symptoms and of internalizing behavior throughout the study but that the improvement slowed after they left school. Furthermore, work by Smith and associates in a sample of 397 individuals with ASD showed changes in daily living skills, with skills improving during adolescence and the early 20s, peaking around the late 20s, and declining in the early 30s. Due to the increased rates, early onset, lifetime persistence, and high levels of associated impairment, ASDs are currently recognized as one of the major public health issues affecting TAY.