Association between the Intron 8 VNTR Polymorphism of the DAT1 Gene and Crack Cocaine Addiction.

BACKGROUND: This study aims to compare allele and genotype frequencies of a 30-bp variable number of tandem repeats (VNTR) polymorphism of the DAT1 gene, located at intron 8, between adult crack cocaine users and nonaddicted individuals. Due to its involvement in drug addiction, this gene is a good candidate for molecular studies. METHODS: A cross-sectional sample of 239 current adult crack abusers or dependents from in- and outpatient clinics and 211 control individuals was collected in Brazil. They were evaluated using ASRS, ASI-6, WAIS-III, and MINI assessments. DNA samples extracted from whole blood were genotyped for the intron 8 VNTR in DAT1. RESULTS: Logistic regression analysis was performed and controlled for gender, age, ethnicity, educational level, and comorbidities of clinical interest (generalized anxiety disorder, suicide risk, major depressive episode, and attention deficit/hyperactivity disorder). This analysis showed that the 6R6R genotype was associated with crack cocaine addiction (OR = 1.844; CI = 1.101-3.089; p = 0.020). CONCLUSIONS: Our results are consistent with the role of DAT1 in the neurobiology of drug addiction. Nevertheless, the study of other genes, environmental factors, and their interactions is also important to gain a broader understanding of this condition.

Crack cocaine users show differences in genotype frequencies of the 3' UTR variable number of tandem repeats of the dopamine transporter gene (DAT1/SLC6A3).

BACKGROUND: Due to the mechanism of action of the dopamine transporter (DAT) in drug addiction, the DAT1 gene is a potential candidate for molecular studies. This paper aims to compare the prevalence of allele and genotype frequencies created by the 3' UTR variable number of tandem repeats (VNTR) of this gene between crack cocaine users and controls. METHODS: A cross-sectional sample of 237 current adult crack cocaine abusers or dependents (DSM-IV TR criteria) from in- and outpatient clinics in southern Brazil and 205 community controls were compared. The subjects were evaluated using the Adult ADHD Self-Report Scale, the Mini-International Neuropsychiatric Interview - short version, and the Wechsler Intelligence Scale. DNA samples were genotyped for the DAT1 3' VNTR. RESULTS: Logistic regression analysis was performed to compare the frequency of the 10.10 genotype (the putative risk genotype) to those of other genotypes. A significant difference (p = 0.04, OR = 1.758, CI = 1.026-3.012) indicating an increased frequency of the 10.10 genotype in the cases (59.9%) compared to the controls (49.3%) was verified using clinical and demographic covariates. CONCLUSIONS: This is one of the first genetic association studies on crack cocaine users in the literature. The results suggest an influence of the DAT1 gene, namely the 3' VNTR 10.10 genotype. However, more analyses will confirm and clarify its contribution as a possible risk factor for crack cocaine dependence.

Prenatal cocaine exposure and its influence on pediatric epigenetic clocks and epigenetic scores in humans.

The investigation of the effects of prenatal cocaine exposure (PCE) on offspring has been inconsistent, with few studies investigating biological outcomes in humans. We profiled genome-wide DNA methylation (DNAm) of umbilical cord blood (UCB) from newborns with (n = 35) and without (n = 47) PCE. We used DNAm data to (1) assess pediatric epigenetic clocks at birth and (2) to estimate epigenetic scores (ES) for lifetime disorders. We generated gestational epigenetic age estimates (DNAmGA) based on Knight and Bohlin epigenetic clocks. We also investigated the association between DNAmGA and UCB serum brain-derived neurotrophic factor (BDNF) levels. Considering the large-scale DNAm data availability and existing evidence regarding PCE as a risk for health problems later in life, we generated ES for tobacco smoking, psychosis, autism, diabetes, and obesity. A gene ontology (GO) analysis on the CpGs included in the ES with group differences was performed. PCE was associated with lower DNAmGA in newborns, and this effect remained significant when controlling for potential confounders, such as blood cell type composition predicted by DNAm and obstetric data. DNAmGA was negatively correlated with BDNF levels in the serum of UCB. Higher tobacco smoking, psychosis, and diabetes ES were found in the PCE group. The GO analysis revealed GABAergic synapses as a potential pathway altered by PCE. Our findings of decelerated DNAmGA and ES for adverse phenotypes associated with PCE, suggest that the effects of gestational cocaine exposure on the epigenetic landscape of human newborns are detectable at birth.

Cognitive impairment in school-aged children with early trauma.

Exposure to traumatic events during childhood is often associated with the development of psychiatric disorders, cognitive impairment, and poor functioning in adulthood. However, few studies have examined cognitive function, including executive function, memory, and attention, in school-aged children with early trauma compared with age- and sex-matched controls. We recruited 30 medication-naive children between 5 and 12 years of age with a history of early severe trauma from a foster care home, along with 30 age- and sex-matched controls. Psychiatric diagnoses were based on Kiddie Schedule for Affective Disorders and Schizophrenia Epidemiologic Version (K-SADS-E) for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and were confirmed with a clinical interview. The neuropsychologic battery was tailored to assess broad cognitive domains such as learning/working memory, executive function, attention, verbal/premorbid intellectual functioning, and impulsivity. There was a higher prevalence of subsyndromal symptoms in children with a history of childhood trauma, although they rarely met all of the diagnostic criteria for a disorder. Moreover, lower estimated intellectual functioning scores were associated with subsyndromal symptoms in children with a history of trauma, and they performed more poorly on the Digits Span Test of the Wechsler Intelligence Scale for Children-III Edition, suggesting attention impairment. There is a high prevalence of subsyndromal symptoms in school-aged children with trauma and an attention impairment, which may contribute to a cumulative deficit early in cognitive development. These findings further support the need for early interventions that can prevent cognitive impairment when childhood trauma occurs.

Molecular imaging genetics of methylphenidate response in ADHD and substance use comorbidity.

PURPOSE: Attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUDs) are highly comorbid and may share a genetic vulnerability. Methylphenidate (MPH), a dopamine transporter (DAT) blocker, is an effective drug for most ADHD patients. Although dopamine D4 receptor (DRD4) and dopamine transporter (DAT1) genes have a role in both disorders, little is known about how these genes influence brain response to MPH in individuals with ADHD/SUDs. The goal of this study was to evaluate whether ADHD risk alleles at DRD4 and DAT1 genes could predict the change in striatal DAT occupancy after treatment with MPH in adolescents with ADHD/SUDs. METHODS: Seventeen adolescents with ADHD/SUDs underwent a SPECT scan with [Tc(99m) ]TRODAT-1 at baseline and after three weeks on MPH. Caudate and putamen DAT binding potential was calculated. Comparisons on DAT changes were made according to the subjects' genotype. RESULTS: The combination of both DRD4 7-repeat allele (7R) and homozygosity for the DAT1 10-repeat allele (10/10) was significantly associated with a reduced DAT change after MPH treatment in right and left caudate and putamen, even adjusting the results for potential confounders (P ≤ 0.02; R² from 0.50 to 0.56). CONCLUSIONS: In patients with ADHD/SUDs, combined DRD4 7R and DAT1 10/10 could index MPH reduced DAT occupancy. This might be important for clinical trials, in terms of better understanding individual variability in treatment response.

Oxytocin Receptor Exon III Methylation in the Umbilical Cord Blood of Newborns With Prenatal Exposure to Crack Cocaine.

BACKGROUND: Prenatal cocaine exposure (PCE) is associated with behavioral, cognitive, and social consequences in children that might persist into later development. However, there are still few data concerning epigenetic mechanisms associated with the effects of gestational cocaine exposure, particularly in human newborns. AIMS: We investigated the effects of PCE on DNA methylation patterns of the Oxytocin Receptor (OXTR) gene in the umbilical cord blood (UCB). The relationship between UCB DNA methylation levels and the severity of the mother's cocaine use during pregnancy was also evaluated. METHODS: In this cross-sectional study, 28 UCB samples of newborns with a history of crack cocaine exposure in utero and 30 UCB samples of non-exposed newborns (NEC) were compared for DNA methylation levels at two genomic loci located in exon III of the OXTR gene (OXTR1 and OXTR2) through pyrosequencing. Maternal psychopathology was investigated using the Mini International Neuropsychiatric Interview, and substance use characteristics and addiction severity were assessed using the Smoking and Substance Involvement Screening Test (ASSIST). RESULTS: No differences between newborns with a history of PCE and NEC were observed in OXTR1 or OXTR2 DNA methylation levels. However, regression analyses showed that maternal addiction severity for crack cocaine use predicted OXTR1 DNA methylation in newborns. CONCLUSION: These data suggest that OXTR methylation levels in the UCB of children are affected by the severity of maternal crack cocaine usage. Larger studies are likely to detect specific changes in DNA methylation relevant to the consequences of PCE.

Impulsivity, age of first alcohol use and substance use disorders among male adolescents: a population based case-control study.

AIMS: To evaluate the association between impulsivity, age of first alcohol consumption (AFD) and substance use disorders (SUD) in a non-clinical sample of adolescents. DESIGN AND SETTING: Population-based case-control study of male adolescents between 15 and 20 years of age nested in a community survey in southern Brazil. PARTICIPANTS: Cases were drug or alcohol abusers/dependents defined according to DSM-IV abuse/dependence criteria (n = 63). Individuals who had experienced alcohol use but where non-abusers served as controls (n = 355). Cases and controls completed a structured face-to-face interview. MEASUREMENTS: The Mini International Neuropsychiatric Interview (MINI) was completed during the original survey and used to identify cases and controls. Impulsivity was measured by means of the Barratt Impulsivity Scale (BIS 11). Self-reported AFD and socio-demographic data were collected and analyzed through logistic regression according to a hierarchical model. FINDINGS: Impulsivity and AFD were significantly associated with SUD. Both higher impulsivity [odds ratio (OR) 3.3, 95% confidence interval (CI) 1.4-7.8] and earlier AFD (OR 1.2, 95% CI 1.0-1.3) remained associated with SUD after model adjustments. CONCLUSIONS: The findings from this population-based case-control study suggest that impulsivity and age of first alcoholic drink are associated strongly with alcohol and drug problems. Additionally, impulsivity seems to contribute to a premature exposure to alcohol by hastening the AFD. If the temporal effect of these associations is confirmed in longitudinal designs including broader population groups, our findings may contribute to the development of clinical and policy interventions aiming at reducing the incidence and morbidity associated with substance-related problems among adolescents.

Attention deficit hyperactivity disorder and substance use disorders.

Attention deficit hperactivity disorder (ADHD) is highly prevalent among adolescents who have substance use disorder (SUD). Several lines of evidence, although not conclusive, suggest that ADHD might have an independent effect on SUD liability. It is still to be determined, however, whether this association is mediated by conduct disorder. This article reviews ADHD and SUD.

Increased cocaine and amphetamine-regulated transcript cord blood levels in the newborns exposed to crack cocaine in utero.

BACKGROUND: Cocaine and amphetamine-regulated transcript (CART) is an endogenous antioxidant present since the embryonic period. CART is activated by high levels of dopamine and might be of interested in understanding the changes in the REDOX system associated with crack/cocaine intake. The goal of this study was to determine whether exposure to crack in utero is associated with increased CART levels. METHODS: In this cross-sectional study with consecutive sampling, we compared the umbilical cord blood (UCB) CART levels (µg/mL) of newborns exposed to crack/cocaine in utero (EN, n = 57) to levels in non-exposed newborns (NEN, n = 99). In addition, we compared serum CART levels between EN and NEN mothers, in the immediate postpartum period. Potential confounders, such as perinatal data (e.g., weight, Apgar, etc.), psychopathology (DSM-IV), and use of drugs other than crack (ASSIST) were assessed. RESULTS: According to general linear model analysis, the adjusted mean CART was significantly higher in EN (0.180, 95% CI 0.088-0.272) than in NEN (0.048, 95% CI 0.020-0.076; p < 0.002; d = 0.68). The difference in CART levels between EN and NEN mothers was not significant (p ≥ 0.05). CONCLUSION: The increase in CART levels in EN UBC suggests a response to crack/cocaine-induced oxidative stress during gestational period, as a potential attempt of neuroprotection. In adult women in puerperium, however, this endogenous antioxidant recruitment does not seem to operate.

Is attention-deficit/hyperactivity disorder associated with illicit substance use disorders in male adolescents? A community-based case-control study.

AIMS: This study aims at evaluating the association between attention-deficit/hyperactivity disorder (ADHD) and illicit substance use disorders (SUD) (marijuana, cocaine and inhalants), controlling for the association with conduct disorder (CD), in a community-based sample of adolescents. DESIGN: Case-control, community-based study. SETTING: A delimited geographical area in the South of Brazil, served by four public health clinics. PARTICIPANTS: A total of 968 male adolescents (15-20 years of age) were screened for SUD in their households. Of the subjects who were screened positive, we selected 61 cases with illicit SUD. For each case we selected, from the group which was screened negative, three controls without illicit or alcohol SUD, matched by age and proximity with the case's household. MEASUREMENTS: The screening instrument was the Alcohol Smoking and Substance Screening Test (ASSIST). SUD diagnoses were assessed by the drug section of the Mini International Neuropsychiatry Interview (MINI). Other psychiatric diagnoses were based on semistructured (Schedule for Affective Disorders and Schizophrenia for School-Age Children-epidemiological version; MINI) and clinical interviews. FINDINGS: Adolescents with ADHD presented a significantly higher odds ratio (OR) for illicit SUD than youths without ADHD, even after adjusting for potential confounders (CD, ethnicity, religion and estimated IQ) (OR = 9.12; 95% CI = 2.84-29.31, P < 0.01). CONCLUSIONS: Our results suggest an association between ADHD and illicit SUD in Brazilian adolescents that is not mediated by CD. These findings are potentially important from a prevention perspective because treatments are available for ADHD.

Adaptation and construct validation of the Barratt Impulsiveness Scale (BIS 11) to Brazilian Portuguese for use in adolescents.

OBJECTIVE: Impulsivity is associated with different psychiatric disorders. The Barratt Impulsiveness Scale version 11 is one of the scales mostly used to measure impulsivity and it does not have a validated version for Brazilian Portuguese. The objective of this study is to adapt and conduct the construct validation of the Barratt Impulsiveness Scale version 11 for adolescents. METHOD: The scale was translated and adapted into Portuguese and then back-translated into English. The psychometric proprieties, factor analysis and construct validity were evaluated in two samples: 18 bilingual undergraduate medical students and 464 male adolescents between 15 and 20 years old from a well-delimited geographical area in the city of Canoas, southern Brazil. RESULTS: The adolescent sample had a mean age of 17.3 +/- 1.7 years. Intra-class correlation coefficient achieved a value of 0.90, and internal consistency had a of 0.62. Factor analysis did not identify the 3 factors of the original scale. Impulsivity scores from the Barratt Impulsiveness Scale version 11 had a correlation with scores for attention deficit/hyperactive disorder and oppositional defiant disorder and with number of symptoms of conduct disorder, suggesting an appropriate construct validity of the scale. CONCLUSION: Even considering some limitations in the Portuguese version, Barratt Impulsiveness Scale version 11 can be used in male adolescents and should be tested in other populations.

TBARS and BDNF levels in newborns exposed to crack/cocaine during pregnancy: a comparative study.

OBJECTIVES:: To compare levels of a marker of lipid peroxidation (thiobarbituric acid reactive substances, TBARS) and brain-derived neurotrophic factor (BDNF) in umbilical cord blood (UCB) between newborns exposed to crack/cocaine in utero (exposed newborns [EN], n=57) and non-exposed newborns (NEN, n=99), as well as in maternal peripheral blood at delivery. METHODS:: This was a cross-sectional study. Potential confounders, including perinatal parameters, psychopathology, and use of other substances, were assessed. RESULTS:: After adjusting for potential confounders, adjusted mean BDNF was significantly higher in EN (3.86 ng/mL, 95% confidence interval [95%CI] 2.29-5.43) than in NEN (0.85 ng/mL, 95%CI 0.47-1.23; p < 0.001; Cohen effect size: 1.12), and significantly lower in crack/cocaine mothers than in control mothers (4.03 ng/mL, 95%CI 2.87-5.18 vs. 6.67 ng/mL, 95%CI 5.60-7.74; p = 0.006). The adjusted mean TBARS level was significantly lower in EN (63.97 µM MDA, 95%CI 39.43-88.50) than NEN (177.04 µM MDA, 95%CI 140.93-213.14; p < 0.001; effect size = 0.84), with no difference between mother groups (p = 0.86). CONCLUSIONS:: The changes in TBARS levels observed in EN suggest that fetuses exposed to cocaine mobilize endogenous antioxidant routes since very early stages of development. The increase in BDNF levels in EN might indicate changes in fetal development, whereas the changes in BDNF levels in mothers provide evidence of the complex metabolic processes involved in drug use during pregnancy.

Differences in biomarkers of crack-cocaine adolescent users before/after abstinence.

AIMS: To measure the variation in Brain-Derived Neurotrophic Factor (BDNF), Thiobarbituric Acid Reactive Substances (TBARS) and interleukin (IL) levels in crack-cocaine dependent adolescents after 21days of abstinence, comparing to levels found in a group of healthy controls. DESIGN: Cross-sectional nested on a short follow-up study. SETTING: Two inpatient treatment units for adolescents, and a low-income neighborhood. PARTICIPANTS: 90 adolescents, of both genders, with diagnosis of crack cocaine dependence, and 81 healthy adolescents. MEASUREMENTS: Serum levels of IL-6, IL-10, TBARS and BDNF were assessed on admission and discharge. Drug addiction severity was assessed by the Addiction Severity Index - Teen Version (T-ASI) and Cocaine Craving Questionnaire - Brief version (CCQ-b). Psychiatric comorbidities were assessed by the Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version (K-SADS-PL). Generalized Estimating Equations (GEE) were used to estimate the IL-6, IL-10, TBARS and BDNF levels, adjusted for confounders. Hedges' g was used to estimate effect size. FINDINGS: TBARS (p=0.005, d=0.04), IL-6 (p=0.027, d=0.40) and IL-10 (p=0.025, d=0.41) were elevated and BDNF (p<0.001, d=0.62) was reduced (p<0.001), in patients, in comparison to controls, at admission time. Variation in those levels between admission and discharge were not significant. CONCLUSIONS: Crack-cocaine use seems to be associated with inflammatory and oxidative imbalances in adolescents.

Effects of crack cocaine addiction and stress-related genes on peripheral BDNF levels.

This study examined the effects of glucocorticoid receptor (NR3C1), corticotropin-releasing hormone receptor 1 (CRHR1), and brain-derived neurotrophic factor (BDNF) genes on susceptibility to crack cocaine addiction and BDNF levels. Crack addicted patients who sought treatment (n = 280) and non-addicted individuals (n = 241) were assessed. Three SNPs in NR3C1 (rs6198, rs41423247, and rs10052957), three in CRHR1 (rs12944712, rs110402, and rs878886), and one in BDNF (rs6265) were genotyped. No significant effect was seen in the case-control analyses. Crack cocaine addicted patients showed significantly lower serum BDNF levels. Significant effects were observed for NR3C1 rs41423247 and rs10052957. These effects were restricted to non-addicted individuals and they were supported by significant gene-by-disease status interactions. For CRHR1, all SNPs were associated with BDNF levels. Although there were significant effects only in the analysis restricted to non-addicted individuals, the lack of significant results in the gene-by-disease status interaction analyses suggest a general effect on BDNF levels. The haplotype analyses presented the same effect seen in the single marker analyses. This study suggests that SNPs in the NR3C1 and CRHR1 genes may influence BDNF levels, but this effect is blunted in the context of crack cocaine addiction. Therefore, our data may be interpreted in light of several studies showing pronounced effects of crack cocaine on BDNF levels. Since peripheral BDNF is a biomarker for several psychiatric phenotypes, our results may be useful in interpreting previous associations between stress-related SNPs, drug addiction, and depression.

IL-6 and IL-10 levels in the umbilical cord blood of newborns with a history of crack/cocaine exposure in utero: a comparative study.

INTRODUCTION: Prenatal cocaine exposure (PCE) is associated with neurobehavioral problems during childhood and adolescence. Early activation of the inflammatory response may contribute to such changes. Our aim was to compare inflammatory markers (IL-6 and IL-10) both in umbilical cord blood and in maternal peripheral blood at delivery between newborns with history of crack/cocaine exposure in utero and non-exposed newborns. METHODS: In this cross-sectional study, 57 newborns with a history of crack/cocaine exposure in utero (EN) and 99 non-exposed newborns (NEN) were compared for IL-6 and IL-10 levels. Sociodemographic and perinatal data, maternal psychopathology, consumption of nicotine and other substances were systematically collected in cases and controls. RESULTS: After adjusting for potential confounders, mean IL-6 was significantly higher in EN than in NEN (10,208.54, 95% confidence interval [95%CI] 1,328.54-19,088.55 vs. 2,323.03, 95%CI 1,484.64-3,161.21; p = 0.007; generalized linear model [GLM]). Mean IL-10 was also significantly higher in EN than in NEN (432.22, 95%CI 51.44-812.88 vs. 75.52, 95%CI 5.64-145.39, p = 0.014; GLM). Adjusted postpartum measures of IL-6 were significantly higher in mothers with a history of crack/cocaine use (25,160.05, 95%CI 10,958.15-39,361.99 vs. 8,902.14, 95%CI 5,774.97-12,029.32; p = 0.007; GLM), with no significant differences for IL-10. There was no correlation between maternal and neonatal cytokine levels (Spearman test, p ≥ 0.28 for all measures). CONCLUSIONS: IL-6 and IL-10 might be early biomarkers of PCE in newborns. These findings could help to elucidate neurobiological pathways underlying neurodevelopmental changes and broaden the range of possibilities for early intervention.

Crack Cocaine Use in Adolescents: Clinical Characteristics and Predictors of Early Initiation.

OBJECTIVE: To describe the clinical characteristics of adolescents with crack cocaine dependence and possible predictors of transition from drug experimentation to crack cocaine dependence. METHODS: This cross-sectional study enrolled a consecutive sample of 90 adolescents admitted to a psychiatric inpatient unit in the city of Porto Alegre in southern Brazil for crack cocaine detoxification between May 2011 and November 2012. Comorbid psychological conditions were assessed using the Kiddie-SADS-Present and Lifetime Version, and severity of drug use was assessed using the Teen Addiction Severity Index (T-ASI). Comorbidities were compared with those in a community sample of non-drug using controls (n = 81). RESULTS: Patients' mean age was 15.6 years (85.6% boys, 14.4% girls). Seventy-nine (93.2%) met criteria for cocaine dependence (DSM-IV-TR), while 78 (91.8%) had symptoms consistent with cocaine abuse. All patients had experimented with at least 1 other addictive substance before crack cocaine: 61.4%, tobacco (mean age at first use = 11.61 years); 44.3%, alcohol (age at first use = 12.43 years); and 54.5%, cannabis (age at first use = 12.15 years). Patients had used crack cocaine 23.2 days in the last month, and the mean age at first use of crack cocaine was 13.38 years. The most common psychiatric comorbidity was conduct disorder (81.8%), followed by oppositional defiant disorder (52.3%) and attention-deficit/hyperactivity disorder (44.3%), all of which were more prevalent in the patient population than in controls (P < .001). The T-ASI questionnaire showed severe consequences of drug use in most areas of life assessed. The mean time between onset of drug experimentation and crack cocaine dependence was 2.53 (SD = 1.96) years. When Cox regression models were applied, we found that predictors of earlier progression to using crack cocaine were age at first use of any drug (hazard ratio [HR] = 0.79 [95% CI, 0.71-0.88]; P < .001) and age at admission (HR = 0.7 [95% CI, 0.57-0.87]; P = .001). CONCLUSIONS: Patients were found to have a multitude of comorbid conditions, which supports the idea of treatment by a multidisciplinary health care team. For each year of delay in the age at first drug use, the chance of crack cocaine initiation is reduced by 18%. Prevention programs aimed at delaying experimentation with addictive substances, especially "gateway" drugs, could delay the progression to crack cocaine dependence.

Attention-deficit/hyperactivity disorder in a diverse culture: do research and clinical findings support the notion of a cultural construct for the disorder?

There is still some debate in the literature whether Attention-Deficit Disorder/Hyperactivity (ADHD) is best conceptualized as a biological disorder or if it is best understood as a cultural construct. This review aims to contribute to disentangle this issue assessing clinical and research data on ADHD in a complete diverse culture from a developing country. We performed a systematic computerized review of the literature on ADHD in Brazil. All investigations were included if dealing with ADHD prevalence, etiology, symptomatological construct, or treatment. Findings were compared to those from studies in developed countries. The prevalence rates of ADHD (5.8% using DSM-IV criteria, 1.5% using ICD-10), the bi-dimensional factor construct extracted from factor analyses (inattention and hyperactivity/impulsivity), the pattern of ADHD comorbidity in clinical samples, the family genetic data suggesting a 39% family transmission in clinical samples and the role of some potential candidate genes in dopaminergic and noradrenergic systems, as well as data on the efficacy of methylphenidate in the disorder are all very similar to findings from developed countries. Taken together, these findings suggest that ADHD is not a cultural construct, reinforcing the importance of applying similar research methodology in different cultures to make findings comparable.

Dopamine transporter gene and response to methylphenidate in attention-deficit/hyperactivity disorder.

This study aims to evaluate whether a previously reported association between homozygosity for the 10-repeat allele of the dopamine transporter gene (10/10) and poor response to methylphenidate (MPH) would be replicated in a sample of Brazilian attention deficit/hyperactivity disorder (ADHD) boys. In a blind naturalistic study, 50 male ADHD youths were treated with MPH. Efficacy of the medication was measured by means of the 10-item Conners Abbreviated Rating Scale (ABRS), and the Children's Global Assessment Scale (CGAS). While 75% (15/20) of the youths without 10/10 genotype demonstrated an improvement higher than 50% in the ABRS scores with MPH, only 47% (14/30) of the subjects with 10/10 genotype achieved the same level of improvement with medication (one-tailed P = 0.04). In addition, the group without this genotype had significantly higher increase in the CGAS scores than the other group (one-tailed P < 0.01). Our findings support an association between homozygosity for the 10-repeat allele at dopamine transporter gene locus and poor response to MPH.

[Alcohol use among adolescents: concepts, epidemiological characteristics and etiopatogenic factors]. / Uso de álcool entre adolescentes: conceitos, características epidemiológicas e fatores etiopatogênicos.

Alcohol is the most consumed substance among young people, and the onset of its use is starting at an earlier age, raising the risks of future dependence. The use of alcohol in adolescence is associated with a series of risk behaviors, besides raising the risk of involvement in accidents, sexual violence, and participating in gangs. Alcohol use by adolescents is strongly associated with violent death, poor academic performance, learning difficulties and damage in the development and structuring of cognitive-behavioral and emotional abilities. Alcohol consumption causes neurochemical modifications, with damage in memory, learning and impulse control. Professionals who deal with adolescents must be prepared for a thorough evaluation regarding the possible abusive use or dependence of alcohol in this age group. However, it is important to emphasize that the criteria utilized by some diagnostic tools for abuse and dependence were developed for adults, and must be applied with caution in adolescents. Thus, it is fundamental that these professionals be aware of the characteristics and peculiarities of adolescence and chemical dependence in this age-group.

Searching for a neurobiological basis for self-medication theory in ADHD comorbid with substance use disorders: an in vivo study of dopamine transporters using (99m)Tc-TRODAT-1 SPECT.

PURPOSE: Attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUD) frequently co-occur. Although several studies have shown changes in striatal dopamine transporter (DAT) density in these disorders, little is known about the neurobiological basis of the comorbidity. The aim of this study was to evaluate striatal DAT density in treatment-naive ADHD adolescents with SUD (ADHD + SUD) and without SUD (ADHD), compared to SUD adolescents without ADHD (SUD) and healthy control subjects (HC). PATIENTS AND METHODS: Sixty-two male age-matched subjects diagnosed with DSM-IV criteria were included: ADHD + SUD (n = 18), SUD (n = 14), HC (n = 19), and ADHD (n = 11). Urine tests confirmed participants' drug use. All subjects performed SPECT scans with Tc-TRODAT-1 to evaluate DAT density in the striatum. RESULTS: The mean right striatum specific binding were 1.68 (ADHD), 1.38 (ADHD + SUD), 1.19 (HC), 1.17 (SUD), and in left striatum 1.65 (ADHD), 1.39 (ADHD + SUD), 1.19 (HC), and 1.17 (SUD). The ADHD group presented significantly higher striatal DAT density compared with ADHD + SUD, SUD, and HC groups. Adolescents with ADHD + SUD had significantly lower DAT density than those with ADHD, but significantly higher DAT density than those with SUD only and no significant difference from the healthy control group. CONCLUSION: The ADHD + SUD group had lower striatal DAT density in comparison with ADHD without SUD. It is possible to speculate that the use of cannabis and cocaine is responsible for the lower striatal DAT density in this group which would help in understanding the neurobiological basis for the self-medication theory in ADHD adolescents.