Adverse Effects of Cannabis on Adolescent Brain Development: A Longitudinal Study.

Cannabis is widely perceived as a safe recreational drug and its use is increasing in youth. It is important to understand the implications of cannabis use during childhood and adolescence on brain development. This is the first longitudinal study that compared resting functional connectivity of frontally mediated networks between 43 healthy controls (HCs; 20 females; age M = 16.5 ± 2.7) and 22 treatment-seeking adolescents with cannabis use disorder (CUD; 8 females; age M = 17.6 ± 2.4). Increases in resting functional connectivity between caudal anterior cingulate cortex (ACC) and superior frontal gyrus across time were found in HC, but not in CUD. CUD showed a decrease in functional connectivity between caudal ACC and dorsolateral and orbitofrontal cortices across time. Lower functional connectivity between caudal ACC cortex and orbitofrontal cortex at baseline predicted higher amounts of cannabis use during the following 18 months. Finally, high amounts of cannabis use during the 18-month interval predicted lower intelligence quotient and slower cognitive function measured at follow-up. These data provide compelling longitudinal evidence suggesting that repeated exposure to cannabis during adolescence may have detrimental effects on brain resting functional connectivity, intelligence, and cognitive function.

Selective neurocognitive impairments in adolescents with major depressive disorder.

This study investigated whether major depression in adolescence is characterized by neurocognitive deficits in attention, affective decision making, and cognitive control of emotion processing. Neuropsychological tests including the Wechsler Abbreviated Scale of Intelligence, the Continuous Performance Test-Identical Pairs, the Attention Network Test, the Iowa Gambling Task, the Emotional Go-NoGo Task, and the Face Go-NoGo Task were administered to adolescents with Major Depressive Disorder (MDD) (n = 31) and psychiatric diagnosis free controls (n = 30). Findings indicated that compared with controls, depressed adolescents exhibited impaired sustained attention; a gender by group interaction on affective decision making such that depressed males tended to make less advantageous choices on the IGT; and an inverse pattern of correlations between depressive symptom counts and reaction time to affective stimuli, characterizing greater affective reactivity in depressed adolescents. Findings demonstrate that adolescents with MDD display selective neurocognitive impairments on tasks capturing 'cool' and 'hot' executive functioning.

Diffusion abnormalities in adolescents and young adults with a history of heavy cannabis use.

BACKGROUND: There is growing evidence that adolescence is a key period for neuronal maturation. Despite the high prevalence of marijuana use among adolescents and young adults in the United States and internationally, very little is known about its impact on the developing brain. Based on neuroimaging literature on normal brain developmental during adolescence, we hypothesized that individuals with heavy cannabis use (HCU) would have brain structure abnormalities in similar brain regions that undergo development during late adolescence, particularly the fronto-temporal connection. METHOD: Fourteen young adult males in residential treatment for cannabis dependence and 14 age-matched healthy male control subjects were recruited. Patients had a history of HCU throughout adolescence; 5 had concurrent alcohol abuse. Subjects underwent structural and diffusion tensor magnetic resonance imaging. White matter integrity was compared between subject groups using voxelwise and fiber tractography analysis. RESULTS: Voxelwise and tractography analyses revealed that adolescents with HCU had reduced fractional anisotropy, increased radial diffusivity, and increased trace in the homologous areas known to be involved in ongoing development during late adolescence, particularly in the fronto-temporal connection via arcuate fasciculus. CONCLUSIONS: Our results support the hypothesis that heavy cannabis use during adolescence may affect the trajectory of normal brain maturation. Due to concurrent alcohol consumption in five HCU subjects, conclusions from this study should be considered preliminary, as the DTI findings reported here may be reflective of the combination of alcohol and marijuana use. Further research in larger samples, longitudinal in nature, and controlling for alcohol consumption is needed to better understand the pathophysiology of the effect of cannabis on the developing brain.

Pediatric depression: issues and treatment recommendations.

Major depressive disorder in adolescents is associated with severe consequences including suicide. Early intervention is crucial for preventing such outcomes. Parents may be reluctant to pursue antidepressant therapy for their children because of concerns about 1) a potential risk of increased suicidal ideation and 2) the effect of these medications on brain development. This article discusses the current data about potential risks associated with antidepressant use in children and adolescents versus the risk of untreated illness on their development. It also reviews recent research that suggests combination treatment involving antidepressant medications such as fluoxetine and cognitive behavioral therapy may be particularly helpful to patients who show poor response to only one of these treatments.

Cerebral glucose metabolism and D2/D3 receptor availability in young adults with cannabis dependence measured with positron emission tomography.

INTRODUCTION: Cannabis users have been reported to have decreased regional cerebral glucose metabolism after short periods of abstinence. The purpose of this study was to measure striatal dopamine receptor (D2/D3) availability and cerebral glucose metabolism with positron emission tomography (PET) in young adults who had a prolonged exposure to cannabis and who had been abstinent for a period of at least 12 weeks. MATERIALS AND METHODS: Six 18-21-year-old male subjects with cannabis dependence in early full remission and six age- and sex-matched healthy subjects underwent PET scans for D2/D3 receptor availability measured with [C11]-raclopride and glucose metabolism measured with [18F]-FDG. All subjects were sober for at least 12 weeks before PET scan procedures. PET data were analyzed with statistical parametric mapping software (SPM99; uncorrected p < 0.001, corrected p < 0.05 at the cluster level). Toxicology screening was performed prior to the PET scan to confirm the lack of drugs of abuse. OBSERVATION AND RESULTS: Striatal D2/D3 receptor availability did not differ significantly between groups. Compared to controls, subjects with cannabis dependence had lower normalized glucose metabolism in the right orbitofrontal cortex, putamen bilaterally, and precuneus. There were no significant correlations between striatal D2/D3 receptor availability and normalized glucose metabolism in any region of the frontal cortex or striatum. CONCLUSION: These findings may reflect both cannabis exposure and adaptive changes that occur after a prolonged period of abstinence. Subsequent studies should address whether metabolic and dopamine receptor effects are associated with either active use or longer-term withdrawal in these relatively young subjects.

Editorial: research progress in early-onset schizophrenia.

A substantial proportion of patients with schizophrenia experience the onset of their illness by age 18. Data from phenomenological, cognitive, neuroimaging, and genetic studies suggest a similar profile of clinical and neurobiological abnormalities between early- and adult-onset patients. However, children and adolescents with schizophrenia have been found to have more severe premorbid neurodevelopmental abnormalities, worse long-term outcome, more cytogenetic anomalies, and potentially greater loading of family histories for schizophrenia and associated spectrum disorders than their adult counterparts. Together, these data support a hypothesis that early-onset schizophrenia may reflect a more severe form of the disorder associated with a greater genetic predisposition. It is anticipated that future imaging and genetic studies of this cohort will provide further insight into the neurodevelopmental origins of schizophrenia and the complexity by which genetic and environmental factors interact to modulate susceptibility and/or disease phenotype. The articles on this theme provide updated findings from brain magnetic resonance imaging, neurocognition, and clinical trials in this unique cohort.

Efficacy and tolerability of second-generation antipsychotics in children and adolescents with schizophrenia.

Early-onset schizophrenia-spectrum (EOSS) disorders (onset of psychotic symptoms before 18 years of age) represent a severe variant associated with significant chronic functional impairment and poor response to antipsychotic treatment. All drugs with proven antipsychotic effects block dopamine D(2) receptors to some degree. The ongoing development of the dopamine and other neurotransmitter receptor systems during childhood and adolescence may affect clinical response and susceptibility to side effects in youth. A literature search was conducted of clinical trials of antipsychotics in children and adolescents with EOSS disorders between 1980 and 2007 from the Medline database, reference lists, and conference proceedings. Trials were limited to double-blind studies of duration of 4 or more weeks that included 15 or more patients. Ten clinical trials were identified. Antipsychotic medications were consistently found to reduce the severity of psychotic symptoms in children and adolescents when compared with placebo. The superiority of clozapine has been now demonstrated relative to haloperidol, standard-dose olanzapine, and "high-dose" olanzapine for EOSS disorders. However, limited comparative data are available regarding whether there are differences among the remaining second-generation antipsychotics (SGAs) in clinical effectiveness. The available data from short-term studies suggest that youth might be more sensitive than adults to developing antipsychotic-related adverse side effects (eg, extrapyramidal side effects, sedation, prolactin elevation, weight gain). In addition, preliminary data suggest that SGA use can lead to the development of diabetes in some youth, a disease which itself carries with it significant morbidity and mortality. Such a substantial risk points to the urgent need to develop therapeutic strategies to prevent and/or mitigate weight gain and diabetes early in the course of treatment in this population.

Limbic structures and networks in children and adolescents with schizophrenia.

Studies of adults with schizophrenia provide converging evidence for abnormalities in the limbic system. Limbic structures that show consistent patient/control differences in both postmortem and neuroimaging studies include the anterior cingulate and hippocampus, although differences in the amygdala, parahippocampal gyrus, and fornix have also been observed. Studies of white matter in children and adolescents with schizophrenia tend to show findings that are more focal than those seen in adults. Interestingly, these focal abnormalities in early-onset schizophrenia tend to be more localized to limbic regions. While it is unclear if these early limbic abnormalities are primary in the etiology of schizophrenia, there is evidence that supports a developmental progression with early limbic abnormalities evolving over time to match the neuroimaging profiles seen in adults with schizophrenia. Alternatively, the aberrations in limbic structures may be secondary to a more widespread or global pathological processes occurring with the brain that disrupt neural transmission. The goal of this article is to provide a review of the limbic system and limbic network abnormalities reported in children and adolescents with schizophrenia. These findings are compared with the adult literature and placed within a developmental context. These observations from neuroimaging studies enrich our current understanding of the neurodevelopmental model of schizophrenia and raise further questions about primary vs secondary processes. Additional research within a developmental framework is necessary to determine the putative etiologic roles for limbic and other brain abnormalities in early-onset schizophrenia.

Neurocognitive deficits in adolescents with schizophrenia: longitudinal stability and predictive utility for short-term functional outcome.

OBJECTIVE: Previous cross-sectional studies in adolescents with early-onset schizophrenia (EOS; onset of psychotic symptoms by 18 years of age) have reported patterns of generalized neurocognitive deficits as compared to healthy comparison subjects (HCSs). Here, the authors examined the longitudinal stability of neuropsychological deficits in adolescents with EOS relative to HCS and the associations of these deficits with short-term functional outcome in patients. METHOD: Fifty-two subjects (26 EOS, 26 HCS) were evaluated using a comprehensive neuropsychological test battery a median of 13 months after baseline examination. The stability of scores and the relationship between baseline test performance and functional outcome in patients was explored. RESULTS: Adolescents with EOS were impaired across neurocognitive domains at baseline and follow-up compared to HCSs; these deficits remained relatively stable over time. Follow-up social/communication, personal living, and community living skills were significantly related to attention/vigilance, working memory and verbal memory at baseline; individual cognitive domains were more strongly related to functional outcome than a global measure of intelligence. CONCLUSIONS: Neuropsychological impairment in patients with EOS appears to remain relatively stable over time regardless of changes in clinical state. In addition, this report offers preliminary support for a longitudinal relationship between neurocognitive performance in specific domains and functional outcome.

Schizophrenia and cannabis use.

Genetic predisposition and environmental risk factors are thought to play a role in the pathophysiology of schizophrenia. Exposure to cannabis is one environmental factor that's being studied for its possible link to development of schizophrenia in adolescents. This article presents evidence that supports the hypothesis that repeated cannabis use could interfere with the development of frontal white matter in some adolescents and may exacerbate anatomic pathology in those with schizophrenia. This putative mechanism may explain the deficits in working memory and worsening in the severity of clinical symptoms in adolescents with schizophrenia who use cannabis.

Decision-making impairments in adolescents with early-onset schizophrenia.

Adolescence is a time of vulnerability for risk-taking behaviors. This is particularly true of adolescents with schizophrenia who present with high rates of substance use as compared to the general population. Using the Iowa Gambling Task (IGT), the authors compared decision-making processes in adolescents with early-onset schizophrenia (onset of psychosis by age 18) to that of healthy volunteers. Fifteen adolescents with schizophrenia (aged 12-21 years) and 25 demographically similar healthy volunteers were administered the IGT. Overall, adolescents with schizophrenia performed significantly worse on the IGT than healthy adolescents as measured by a significant group by block interaction. Post-hoc testing revealed that adolescents with schizophrenia performed more poorly than healthy adolescents during the last two blocks of the task. Mathematical modeling further indicated that adolescents with schizophrenia allocated significantly more attention to monetary gains than losses encountered during the task, suggesting a hypersensitivity to rewards and relative insensitivity to future consequences. This is similar to what has been reported for adults with externalizing forms of psychopathology, such as those who abuse substances. These findings have potential implications for understanding the increased vulnerability for the development of substance abuse in adolescents with schizophrenia.

Deficits in memory strategy use are related to verbal memory impairments in adolescents with schizophrenia-spectrum disorders.

OBJECTIVE: To assess the nature of learning and verbal memory deficits in adolescents with schizophrenia-spectrum disorders (SzS) (i.e., schizophrenia, schizoaffective disorder, and schizophreniform disorder). METHOD: Sixty patients with SzS (mean age=16.1 years, S.D. = 2.2) and 60 age- and gender-matched diagnosis-free healthy volunteers were assessed using the California Verbal Learning Test (CVLT). Planned analyses were conducted to assess the following aspects of memory: span of apprehension, verbal learning, short-term and long-term memory, rate of forgetting, interference, and organizational strategies. Adolescents with schizophrenia (Sz) were compared to those with schizoaffective disorder (SzA). Second, patients' test profiles were compared to those of controls. Relationships between initial learning and overall verbal learning with organizational strategy were explored. RESULTS: Neurocognitive profiles did not significantly differ between Sz and SzA participants. Patients performed significantly worse than healthy comparison subjects on measures of span of apprehension, verbal learning, short- and long-term memory, and organizational strategies after adjusting for differences in premorbid intelligence. No group differences were found in rate of forgetting or susceptibility to proactive or retroactive interference. CONCLUSIONS: Adolescents with SzS are characterized by significant verbal memory dysfunction similar to what has been observed in adults with first-episode schizophrenia. Deficits in consistency of learning over several trials, as well as a strong relationship between semantic organizational strategies and reduced learning capacity, implicate dysfunction of the dorsolateral prefrontal cortex as a contributor to verbal memory deficits in adolescents with SzS.

Early-onset schizophrenia is associated with impaired adolescent development of attentional capacity using the identical pairs continuous performance test.

The authors examined performance on the Continuous Performance Test-Identical Pairs "numbers" task in adolescents with schizophrenia (n=59) and healthy controls (n=55). Adjusting for an estimate of premorbid intelligence and socioeconomic status, patients performed worse than normal controls on all three d' conditions (2-digit, 3-digit, 4-digit). However, there was a significant group-by-age-by-condition interaction (F[4,100]=4.69, p<.01) indicating an interaction between development and disease state. At the simplest level of the task (2-digit) the difference between patients with schizophrenia and controls was evident at all ages; while for the more difficult levels of the task (3-digit, 4-digit), differences between groups gradually increased across the tested age span (10 to 20 years of age). Premorbid social isolation was associated with worse attentional performance in patients, suggesting a relationship and continuity with negative symptoms. These data suggest that attentional differences in adolescents with schizophrenia are better captured by different tasks at different ages. The discrepant findings of attentional impairments reported in the literature for adolescents with schizophrenia could reflect the underlying etiological complexity of the disorder that may have a variable impact on involved brain regions and neurocognitive functioning.

Ethical and practical considerations in the management of incidental findings in pediatric MRI studies.

OBJECTIVE: The authors examined the ethical and practical management issues resulting from the detection of incidental abnormal findings on magnetic resonance imaging (MRI) research studies in healthy pediatric volunteers. METHOD: A retrospective examination of the findings from 60 clinical reports of research MRI scans from a cohort of healthy pediatric volunteers (ages 10-21) was conducted. RESULTS: A neuroradiologist noted incidental abnormalities in 8 (13%) of 60 subjects. Of these eight children, three (5%) adolescents were found to have abnormalities (possible tumor, possible vascular malformation, and unidentified bright object in white matter, respectively) that were judged to require further diagnostic workup. In the first two cases, follow-up MRI ruled out the possibility of a tumor or vascular malformation. In the third case, a follow-up MRI 24 months later found that the white matter abnormality remained stable and was thus deemed to be of no clinical significance. CONCLUSIONS: In healthy children who are participating in research MRI protocols, it is ethically difficult to determine whether films should be read clinically. Based on this retrospective analysis, there would have been no risk(s) associated with not reading the films. In contrast, considerable anxiety was generated as a consequence of having the scans clinically read by a neuroradiologist because of the reporting of incidental abnormalities that later turned out to be false positives. Also, the detection of no abnormality on a research-quality scan could imply erroneously to some subjects that no abnormality was present, which may have been falsely reassuring.

Treatment-refractory schizophrenia in children and adolescents: an update on clozapine and other pharmacologic interventions.

Treatment-refractory early-onset schizophrenia is a rare but severe form of the disorder associated with poor premorbid function and long-term disability. The currently available evidence suggests that clozapine remains the most efficacious treatment for the amelioration of both positive and negative symptoms of the disorder and problematic aggressive behaviors. Clozapine use in children and adolescents, however, is limited by its association with hematologic adverse events and an increased frequency of seizure activity. Further studies are needed to examine the usefulness of antipsychotic combinations and of augmentation therapies to antipsychotic medications in order to treat persistent residual psychotic symptoms in children and adolescents who have schizophrenia and who have not responded to several sequential trials of antipsychotic monotherapy.

Neurocognitive profile in adolescents with early-onset schizophrenia: clinical correlates.

BACKGROUND: Neurocognitive impairments have been documented in adolescents with early-onset schizophrenia (EOS; onset by age 18) and are important treatment targets. Information concerning the severity, pattern, and clinical correlates of these deficits in EOS remains limited. METHODS: Tests assessing motor skills, attention, memory, visuospatial abilities and executive functioning were administered to 54 clinically stabilized adolescents with EOS and 52 age- and sex-matched healthy controls. Childhood-onset patients (onset by age 13) were compared to those with an adolescent onset of illness. Patients' neurocognitive profiles were compared to those of controls. Relationships between neurocognitive deficits and demographic and clinical characteristics were explored. RESULTS: Neurocognitive profiles did not differ between childhood- and adolescent-onset participants. Patients showed a generalized neurocognitive deficit of 2.0 SDs compared to controls, with relative deficit in executive functioning and relative sparing of language and visuospatial abilities. Degree of generalized neurocognitive impairment was associated with premorbid adjustment and negative symptom severity (Adjusted R(2) = .39). CONCLUSIONS: Results document both a significant generalized deficit and a relative deficit of executive functioning in adolescents with EOS. The overall pattern is similar to that observed in severely ill first-episode adult patients. The impairments across multiple neurocognitive domains suggest widespread brain dysfunction in EOS.

Attention-deficit/hyperactivity disorder: a preliminary diffusion tensor imaging study.

BACKGROUND: The purpose of this study was to explore whether there are white matter (WM) abnormalities in children with attention-deficit/hyperactivity disorder (ADHD) using diffusion tensor imaging. Based upon the literature, we predicted decreased fractional anisotropy (FA) findings in the frontal and cerebellar regions. METHODS: Eighteen patients with ADHD and 15 age- and gender-matched healthy volunteers received DTI assessments. Fractional anisotropy maps of WM were compared between groups with a voxelwise analysis after intersubject registration to Talairach space. RESULTS: Children with ADHD had decreased FA in areas that have been implicated in the pathophysiology of ADHD: right premotor, right striatal, right cerebral peduncle, left middle cerebellar peduncle, left cerebellum, and left parieto-occipital areas. CONCLUSIONS: These preliminary data support the hypothesis that alterations in brain WM integrity in frontal and cerebellar regions occur in ADHD. The pattern of decreased FA might implicate the corticopontocerebellar circuit in the pathophysiology of ADHD.

White matter abnormalities in first-episode schizophrenia or schizoaffective disorder: a diffusion tensor imaging study.

OBJECTIVE: The goal of this study was to investigate brain white matter abnormalities by using diffusion tensor imaging in patients with schizophrenia or schizoaffective disorder close to illness onset. METHOD: Ten patients experiencing a first episode of schizophrenia or schizoaffective disorder and 13 healthy volunteers received diffusion tensor imaging and structural magnetic resonance imaging examinations. Voxel-wise analysis was used to compare fractional anisotropy maps in the white matter of the two groups following intersubject registration to Talairach space. RESULTS: Compared with healthy volunteers, patients demonstrated lower fractional anisotropy in the left internal capsule and left-hemisphere white matter of the middle frontal gyrus and posterior superior temporal gyrus. There were no areas of significantly higher fractional anisotropy in patients compared with healthy volunteers. CONCLUSIONS: These findings suggest that white matter pathology is present early in the course of schizophrenia and may be less pronounced than has been found in previous diffusion tensor imaging studies of patients with chronic illness. Further, these data are consistent with hypotheses regarding frontotemporal dysfunction and the failure of left-hemisphere lateralization in the pathophysiology of schizophrenia.

Clozapine: its impact on aggressive behavior among children and adolescents with schizophrenia.

OBJECTIVE: To evaluate the effectiveness of clozapine on aggressive behavior for treatment-refractory adolescents (age range 8.5-18) with schizophrenia (295.x) at Bronx Children's Psychiatric Center. METHOD: Clozapine treatment was administered in an open-label fashion using a flexible titration schedule. The frequency of administration of emergency oral and injectable medications and the frequency of seclusion events 3 months immediately before and from 12 to 24 weeks of clozapine treatment (when optimal clozapine levels were achieved) were compared. RESULTS: Twenty clozapine-treated children (mean +/- SD dose at week 24, 476 +/- 119 mg) were included. A statistically significant decrease in the frequency of the administration of emergency oral medications, the administration of emergency injectable medications, and seclusion events was found in adolescents during weeks 12 to 24 of clozapine treatment compared with their baseline condition before clozapine initiation. CONCLUSIONS: These preliminary data indicate the benefits of clozapine treatment in adolescents with treatment-refractory schizophrenia for aggressive behaviors. Although open data limit conclusions from this study, it is important that there was a clinically significant improvement in aggressive behaviors that enabled patients to be discharged to a less restrictive setting. Additional controlled clinical trials of clozapine are needed in treatment-refractory children and adolescents.

Hematological adverse events in clozapine-treated children and adolescents.

OBJECTIVE: To retrospectively examine rates of hematological adverse events (HAEs) in psychiatrically ill, hospitalized children treated with clozapine. METHOD: Clozapine treatment was administered in an open-label fashion using a flexible titration schedule, and data from weekly complete blood counts was obtained. The rate of neutropenia and agranulocytosis (HAEs) development was determined for 172 eligible patients (mean age at clozapine initiation, 15.03 +/- 2.13 years) with a median observation period of 8 months. RESULTS: Neutropenia (absolute neutrophil count <1,500/mm) developed in 23 (13%) patients and agranulocytosis (absolute neutrophil count <500/mm) in one (0.6%) patient. The cumulative probability of developing an initial HAE at 1 year of clozapine treatment was 16.1% (95% confidence interval 9.7%-22.5%). Eleven (48%) of 24 patients who developed an HAE were successfully rechallenged on clozapine. Eight (5%) of 172 patients from this sample eventually discontinued clozapine because of an HAE (one agranulocytosis, seven neutropenia). CONCLUSIONS: The occurrence of HAEs is a significant risk associated with the administration of clozapine. However, in this sample, few children actually discontinued therapy because of an HAE and the incidence of agranulocytosis does not appear higher than what has been reported in the adult literature.