Andrew Smolen - Academia.edu (original) (raw)

Papers by Andrew Smolen

European Journal of Human Genetics

Some of the most widely studied variants in psychiatric genetics include variable number tandem r... more Some of the most widely studied variants in psychiatric genetics include variable number tandem repeat variants (VNTRs) in SLC6A3, DRD4, SLC6A4, and MAOA. While initial findings suggested large effects, their importance with respect to psychiatric phenotypes is the subject of much debate with broadly conflicting results. Despite broad interest, these loci remain absent from the largest available samples, such as the UK Biobank, limiting researchers' ability to test these contentious hypotheses rigorously in large samples. Here, using two independent reference datasets, we report out-of-sample imputation accuracy estimates of >0.96 for all four VNTR variants and one modifying SNP, depending on the reference and target dataset. We describe the imputation procedures of these candidate variants in 486,551 UK Biobank individuals, and have made the imputed variant data available to UK Biobank researchers. This resource, provided to the scientific community, will allow the most rigorous tests to-date of the roles of these variants in behavioral and psychiatric phenotypes.

International journal of obesity (2005), Jan 22, 2018

Although childhood attention deficit hyperactivity disorder (ADHD) has been previously associated... more Although childhood attention deficit hyperactivity disorder (ADHD) has been previously associated with concurrent and later obesity in adulthood, the etiology of this association remains unclear. The objective of this study is to determine the shared genetic effects of ADHD symptoms and BMI in a large sample of sibling pairs, consider how these shared effects may vary over time, and examine potential sex differences. Sibling pair data were obtained from the National Longitudinal Study of Adolescent to Adult Health (Add Health); childhood ADHD symptoms were reported retrospectively during young adulthood, while three prospective measurements of BMI were available from young adulthood to later adulthood. Cholesky decomposition models were fit to this data using Mx and maximum-likelihood estimation. The twin and sibling sample for these analyses included: 221 monozygotic (MZ) pairs (92 male-male, 139 female-female), 228 dizygotic (DZ) pairs (123 male-male, 105 female-female), 471 full-...

Frontiers in human neuroscience, 2018

A critical problem for developing personalized treatment plans for cognitive disruptions is the l... more A critical problem for developing personalized treatment plans for cognitive disruptions is the lack of understanding how individual differences influence cognition. Recognition memory is one cognitive ability that varies from person to person and that variation may be related to different genetic phenotypes. One gene that may impact recognition memory is the monoamine oxidase A gene (), which influences the transcription rate of MAO-A. Examination of howphenotypes impact behavioral and event-related potentials (ERPs) correlates of recognition memory may help explain individual differences in recognition memory performance. Therefore, the current study uses electroencephalography (EEG) in combination with genetic phenotyping of thegene to determine how well-characterized ERP components of recognition memory, the early frontal old/new effect, left parietal old/new effect, late frontal old/new effect, and the late posterior negativity (LPN) are impacted byphenotype during item and sou...

American heart journal, 2017

Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular rea... more Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore. Logistic regression and linear models tested associations between triallelic (L'S', based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N=11,815) in 2008-09 and during 2004-07 in 4196 Singaporeans. In US Whites, L' allele carriers had higher SBP (0.9 mm Hg, 95% CI=0.26-1.56) and greater odds (OR=1.23, 95% CI=1.10-1.38) of more severe hypertension than those with S'S' genotypes. In African Americans, ...

Clinical psychological science : a journal of the Association for Psychological Science, 2016

Attention bias to emotion may be an intermediate trait for stress-reactive psychopathology associ... more Attention bias to emotion may be an intermediate trait for stress-reactive psychopathology associated with biologically plausible candidate genes, yet the precise direction of effects within the youth literature remains unclear. The present study investigated whether stressful life events (SLEs) moderate the link between genetic risk (5-HTTLPR and COMT) and attention bias to emotion among youth (n= 467). Analyses revealed a differential effect of gene. Among youth who had experienced more recent SLEs, those homozygous for the low expressing allele of 5-HTTLPR (S/S) demonstrated preferential attention toward negative emotional expressions, whereas youth homozygous for the high expressing COMT genotype (Val/Val) showed attentional avoidance of positive facial expressions. No interaction between 5-HTTLPR and COMT was found. These findings highlight the importance of investigating stress as a moderator within the intermediate trait literature and suggest that biologically plausible cand...

Attachment & human development, 2017

In this paper, we examine the associations between specific candidate genes (DRD2, DRD4, COMT, bi... more In this paper, we examine the associations between specific candidate genes (DRD2, DRD4, COMT, biallelic and tri-allelic 5HTTLPR, and OXTR) and infant attachment outcomes as main effects and in conjunction with maternal sensitivity. The sample included 200 infants (97 European American, 94 African-American, and 9 biracial) and their mothers. Maternal sensitivity and overtly negative maternal behavior were observed when infants were 6 months and 1 year old in distress-eliciting contexts, attachment was assessed via the Strange Situation at age 1, and DNA samples were collected when children were 2 years old. Consistent with recent research in large samples, there was little evidence that these genes are associated with attachment security, disorganization, or distress as main effects (in additive, dominant, and homozygous models) or in conjunction with maternal sensitivity or overtly negative behavior (primarily dominance models). Furthermore, there was little evidence that associati...

Drug and Alcohol Dependence, 2007

Pharmacology Biochemistry and Behavior, Apr 30, 1985

PloS one, 2016

The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphis... more The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphism has been implicated to moderate the relationship between the experience of stressful life events (SLEs) and depression. Despite numerous attempts at replicating this observation, results remain inconclusive. We examined this relationship in young-adult Non-Hispanic white males and females between the ages of 22 and 26 (n = 4724) participating in the National Longitudinal Study of Adolescent to Adult Health (Add Health) with follow-up information every six years since 1995. Linear and logistic regression models, corrected for multiple testing, indicated that carriers of one or more of the S-alleles were more sensitive to stress than those with two L-alleles and at a higher risk for depression. This relationship behaved in a dose-response manner such that the risk for depression was greatest among those who reported experiencing higher numbers of SLEs. In post-hoc analyses we were not ab...

Biological Psychiatry, Jan 5, 2006

A promoter polymorphism in the serotonin transporter (5HTTLPR) has functional effects on an impor... more A promoter polymorphism in the serotonin transporter (5HTTLPR) has functional effects on an important physiologic process involved in serotonin (5HT) signaling. Despite the fact that variation in the 5HT system has long been implicated in the etiology of aggressive behaviors, only a few association-based studies with mixed results have been reported. We conducted family-based tests of association in a sample of 366 families from which 1187 genotypes of the 5HTTLPR were generated using polymerase chain reaction. Ratings of aggressive behavior were obtained from parents and teachers longitudinally using the Child Behavior Checklist (CBCL) and Teacher Report Form (TRF), instruments widely used in behavioral and psychiatric genetics. Within-family tests suggest an association between the s-allele of the 5HTTLPR and higher aggressive behavior in middle childhood. The strongest association was at age 9 and for an aggregate measure of teacher-rated aggressive behavior. This is the first report of an association analysis of the 5HTTLPR in a general population sample of school-age children. The results provide some support for the hypothesis that the functional effects of the 5HTTLPR s-allele are associated with higher levels of aggressive behavior in middle childhood.

Journal of abnormal psychology, 2015

Depression is a debilitating mental illness with clear developmental patterns from childhood thro... more Depression is a debilitating mental illness with clear developmental patterns from childhood through late adolescence. Here, we present data from the Gene Environment Mood (GEM) study, which used an accelerated longitudinal cohort design with youth (N = 665) starting in 3rd, 6th, and 9th grades, and a caretaker, who were recruited from the general community, and were then assessed repeatedly through semistructured diagnostic interviews every 6 months over 3 years (7 waves of data) to establish and then predict trajectories of depression from age 8 to 18. First, we demonstrated that overall prevalence rates of depression over time, by age, gender, and pubertal status, in the GEM study closely match those trajectories previously obtained in past developmental epidemiological research. Second, we tested whether a genetic vulnerability-stress model involving 5-HTTLPR and chronic peer stress was moderated by developmental factors. Results showed that older aged adolescents with SS/SL gen...

Social Science Research, 2015

Although stressful life events during adolescence are associated with the adoption of unhealthy b... more Although stressful life events during adolescence are associated with the adoption of unhealthy behaviors such as smoking, both social circumstances and physical traits can moderate the relationship. This study builds on the stress paradigm and gene-environment approach to social behavior by examining how a polymorphism in the serotonin transporter gene 5-HTTLPR moderates the effect of life events on adolescent smoking. Tests of interaction hypotheses use data from the Family Transitions Project, a longitudinal study of 7th graders followed for 5years. A sibling-pair design with separate models for the gender composition of pairs (brothers, sisters, or brother/sister) controls for unmeasured family background. The results show that negative life events are significantly and positively associated with smoking. Among brother pairs but not other pairs, the results provide evidence of gene-environment interaction by showing that life events more strongly influence smoking behavior for those with more copies of the 5-HTTLPR S allele.

The Open Family Studies Journal, 2009

This article's objectives are twofold: (a) to disclose the possible distortion of the association... more This article's objectives are twofold: (a) to disclose the possible distortion of the associations found in the reductionist research that prevails in many areas, in order to ensure greater caution and better understanding of such research. (b) To study the associations between family and parental factors and adolescent psychological disorders (PD) according to a systemic model that analyses eight familial factors and eleven parental factors in addition to two nominal ones: culture and the adolescents' sex. The study is based on a data collected from nine countries (1358 male and 1526 female adolescents), regarding two categories of family factors (socio-economic and connectedness) and three categories of parenting factors (control, inconsistency, and rejection) and adolescent psychological disorders (PD). To compare different levels of reductionism, four analyses of the same data were carried out, ranging from an analysis of the associations between each factor and adolescent PD (reductionist), to analysis of the associations between all the factors taken together (systemic) and adolescent PD. In addition, the systemic analysis was carried out among different groups of adolescents according to two nominal variables: culture (western and eastern) and the adolescents' sex (male female). Our results show that in a reductionist analysis most of the family and parental factors have significant associations with adolescents PD, and altogether explain 37.2% of adolescents' PD. Most of these associations were diminished or changed in the systemic analysis and explained only 13.5% of the PD variance. The associations of the more systemic analysis changed again when two nominal factors (culture and sex) were taken into consideration. These findings indicate that reductionist analyses may lead to illusionary associations and that mixed results are an inevitable or even inherent byproduct of reductionist research.

Journal of Studies on Alcohol and Drugs, 2007

Objective-Dopaminergic dysfunction has been hypothesized to play an important role in the etiolog... more Objective-Dopaminergic dysfunction has been hypothesized to play an important role in the etiology of alcohol use disorders. A restriction fragment length polymorphism (RFLP) in the 3' untranslated region (3'UTR) of the DRD2 gene affects gene expression and has been implicated as a risk factor for alcohol dependence. This polymorphism (TaqIA) has been reported as positively associated with alcohol use disorders in case-control samples, but these results have not been replicated in family-based association studies. These mixed results of association between the DRD2 TaqIA polymorphism and alcohol use disorders may be due to differences in sample size, phenotype definition, heterogeneity of the samples and genetic admixture. Method-We conducted tests of association in a sample of 838 adults participating in the National Youth Survey Family Study (NYSFS). We examined whether the DRD2 TaqIA polymorphism was associated with a symptom counts measure of alcohol abuse and dependence derived from the DSM-IV and Craving Withdrawal models. Results-Tests of association were non-significant across each classification system examined. Power calculations suggested these results were despite the ability to detect an effect size of 1%. Conclusions-This study supports other family-based association tests that have reported no association between the DRD2 TaqIA polymorphism and alcohol abuse and dependence.

Background: The Brain Reward Cascade (BRC) is an interaction of neurotransmitters and their respe... more Background: The Brain Reward Cascade (BRC) is an interaction of neurotransmitters and their respective genes to control the amount of dopamine released within the brain. Any variations within this pathway, whether genetic or environmental (epigenetic), may result in addictive behaviors or RDS, which was coined to define addictive behaviors and their genetic components. Methods: To carry out this review we searched a number of important databases including: Filtered: Cochrane Systematic reviews; DARE; Pubmed Central Clinical Quaries; National Guideline Clearinghouse and unfiltered resources: PsychINFO; ACP PIER; PsychSage; Pubmed/Medline. The major search terms included: dopamine agonist therapy for Addiction; dopamine agonist therapy for Reward dependence; dopamine antagonistic therapy for addiction; dopamine antagonistic therapy for reward dependence and neurogenetics of RDS. Results: While there are many studies claiming a genetic association with RDS behavior, not all are scienti...

Developmental pharmacology and therapeutics, 1981

A 3-fold increase in aldehyde dehydrogenase (A1DH) was found in the cytosolic fraction of mouse l... more A 3-fold increase in aldehyde dehydrogenase (A1DH) was found in the cytosolic fraction of mouse liver homogenates during pregnancy. The increase in A1DH activity began at day 10 of pregnancy, peaked at parturition, and declined in a biphasic manner with half-lives of 4.15 and 47.7 days. Enzymes from control (beta A1DH), pregnant (pi A1DH) and phenobarbital-treated (phi AlDH) were partially purified and compared. All had molecular weights of approximately 60,000 daltons. Substrate specificities were similar except that phi A1DH had a lower Km for propionaldehyde than beta or pi and both pi and phi oxidized 4-carboxybenzaldehyde poorly compared to beta. Electrophoretic and thermal denaturation studies showed some similarities between beta and pi, but phi A1DH behaved quite differently. It was concluded that pregnancy caused an increase in one of the A1DHs already present in control mice, while phenobarbital treatment resulted in induction of a unique cytosolic A1DH.

Alcohol and drug research, 1987

The duration of loss of the righting response (sleep time) is often used to assess central nervou... more The duration of loss of the righting response (sleep time) is often used to assess central nervous system sensitivity to ethanol. It has been assumed that there is a threshold concentration of ethanol at which an animal will regain the righting response, and that this level should not change with dose or route of administration of ethanol. Five hypnotic doses of ethanol were given to Long-sleep and Short-sleep mice by intraperitoneal injection. At the time of awakening, blood and brain ethanol levels were measured. It was found that within a line, the animals awoke at the same blood and brain ethanol concentration irrespective of the ethanol dose given. The threshold blood ethanol level was 265 mg% for Long-Sleep males and 484 mg% for Short-Sleep males. These results indicate that there is a threshold value for ethanol, and that this threshold is characteristic for a given mouse line.

The Journal of nutrition, 1989

A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and exper... more A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and experimental animals for reasons that are not known. To determine if mice also develop decreased plasma PLP concentrations during pregnancy, and if plasma PLP levels in pregnancy reflect tissue levels of PLP and pyridoxamine-5'-phosphate (PMP), we measured PLP concentrations in plasma, erythrocytes and whole blood, and liver and brain PLP and PMP in control and pregnant mice. Mice were fed a nonpurified diet containing 8.13 mg pyridoxine-HCl/kg. The PLP analyses were performed in our newly developed apotryptophanase method in which the substrate S-benzyl-L-cysteine is hydrolyzed to benzyl mercaptan, reacted with Ellman's reagent and measured spectrophotometrically. During pregnancy, plasma PLP levels decreased 50% below control levels, but erythrocyte and whole blood PLP levels increased 2.9- and 1.6-fold, respectively. Liver PLP and PMP decreased 25%, in parallel with plasma PLP, but...

The Journal of nutrition, 1990

Plasma pyridoxal 5'-phosphate (PLP) concentrations are considered to be the most reliable sin... more Plasma pyridoxal 5'-phosphate (PLP) concentrations are considered to be the most reliable single indicator of vitamin B-6 nutritional status and are thought to reflect tissue PLP and pyridoxamine 5'-phosphate (PMP) levels. We investigated the relationship between dietary level of pyridoxine hydrochloride (PN-HCl) and concentrations of PLP in blood and PLP and PMP in liver and brain of mice. Female heterogeneous stock mice, 60 to 90 d old, were fed purified diets containing 0.5, 1.0, 2.0, 3.0, 5.0, or 7.0 mg PN-HCl/kg diet for 5 wk. PLP and PMP concentrations were determined by a spectrophotometric apotryptophanase assay. PLP content of plasma, erythrocytes, whole blood, liver and brain and PMP levels in liver and brain were highly correlated with dietary level of PN-HCl (r values ranged from 0.81 to 0.94, n per correlation = 32 to 43). By using the entire range of dietary levels of PN-HCl, both plasma and erythrocyte PLP were found to be significantly correlated with tissue ...

The Journal of nutrition, 1990

Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythroc... more Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythrocyte PLP levels increase threefold over nonpregnant levels. These studies were designed to determine whether changes in the enzymes involved in synthesis and degradation of PLP in blood are altered during pregnancy. We measured net synthesis of PLP in erythrocytes and the activity of enzymes involved in the regulation of plasma and erythrocyte PLP concentration: erythrocyte pyridoxal kinase (PLK) and neutral phosphatase, and plasma and tissue alkaline phosphatase (ALP). Net synthesis of PLP and activities of erythrocyte PLK and neutral phosphatase in erythrocytes remained unchanged during pregnancy. We were unable to detect any dephosphorylation of PLP in erythrocytes of pregnant or nonpregnant mice. Mouse erythrocytes were devoid of ALP activity; neutral phosphatase was inactive with PLP and PLP was an uncompetitive inhibitor of the enzyme. Plasma ALP activity decreased 50% in the pregna...

European Journal of Human Genetics

Some of the most widely studied variants in psychiatric genetics include variable number tandem r... more Some of the most widely studied variants in psychiatric genetics include variable number tandem repeat variants (VNTRs) in SLC6A3, DRD4, SLC6A4, and MAOA. While initial findings suggested large effects, their importance with respect to psychiatric phenotypes is the subject of much debate with broadly conflicting results. Despite broad interest, these loci remain absent from the largest available samples, such as the UK Biobank, limiting researchers' ability to test these contentious hypotheses rigorously in large samples. Here, using two independent reference datasets, we report out-of-sample imputation accuracy estimates of >0.96 for all four VNTR variants and one modifying SNP, depending on the reference and target dataset. We describe the imputation procedures of these candidate variants in 486,551 UK Biobank individuals, and have made the imputed variant data available to UK Biobank researchers. This resource, provided to the scientific community, will allow the most rigorous tests to-date of the roles of these variants in behavioral and psychiatric phenotypes.

International journal of obesity (2005), Jan 22, 2018

Although childhood attention deficit hyperactivity disorder (ADHD) has been previously associated... more Although childhood attention deficit hyperactivity disorder (ADHD) has been previously associated with concurrent and later obesity in adulthood, the etiology of this association remains unclear. The objective of this study is to determine the shared genetic effects of ADHD symptoms and BMI in a large sample of sibling pairs, consider how these shared effects may vary over time, and examine potential sex differences. Sibling pair data were obtained from the National Longitudinal Study of Adolescent to Adult Health (Add Health); childhood ADHD symptoms were reported retrospectively during young adulthood, while three prospective measurements of BMI were available from young adulthood to later adulthood. Cholesky decomposition models were fit to this data using Mx and maximum-likelihood estimation. The twin and sibling sample for these analyses included: 221 monozygotic (MZ) pairs (92 male-male, 139 female-female), 228 dizygotic (DZ) pairs (123 male-male, 105 female-female), 471 full-...

Frontiers in human neuroscience, 2018

A critical problem for developing personalized treatment plans for cognitive disruptions is the l... more A critical problem for developing personalized treatment plans for cognitive disruptions is the lack of understanding how individual differences influence cognition. Recognition memory is one cognitive ability that varies from person to person and that variation may be related to different genetic phenotypes. One gene that may impact recognition memory is the monoamine oxidase A gene (), which influences the transcription rate of MAO-A. Examination of howphenotypes impact behavioral and event-related potentials (ERPs) correlates of recognition memory may help explain individual differences in recognition memory performance. Therefore, the current study uses electroencephalography (EEG) in combination with genetic phenotyping of thegene to determine how well-characterized ERP components of recognition memory, the early frontal old/new effect, left parietal old/new effect, late frontal old/new effect, and the late posterior negativity (LPN) are impacted byphenotype during item and sou...

American heart journal, 2017

Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular rea... more Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore. Logistic regression and linear models tested associations between triallelic (L'S', based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N=11,815) in 2008-09 and during 2004-07 in 4196 Singaporeans. In US Whites, L' allele carriers had higher SBP (0.9 mm Hg, 95% CI=0.26-1.56) and greater odds (OR=1.23, 95% CI=1.10-1.38) of more severe hypertension than those with S'S' genotypes. In African Americans, ...

Clinical psychological science : a journal of the Association for Psychological Science, 2016

Attention bias to emotion may be an intermediate trait for stress-reactive psychopathology associ... more Attention bias to emotion may be an intermediate trait for stress-reactive psychopathology associated with biologically plausible candidate genes, yet the precise direction of effects within the youth literature remains unclear. The present study investigated whether stressful life events (SLEs) moderate the link between genetic risk (5-HTTLPR and COMT) and attention bias to emotion among youth (n= 467). Analyses revealed a differential effect of gene. Among youth who had experienced more recent SLEs, those homozygous for the low expressing allele of 5-HTTLPR (S/S) demonstrated preferential attention toward negative emotional expressions, whereas youth homozygous for the high expressing COMT genotype (Val/Val) showed attentional avoidance of positive facial expressions. No interaction between 5-HTTLPR and COMT was found. These findings highlight the importance of investigating stress as a moderator within the intermediate trait literature and suggest that biologically plausible cand...

Attachment & human development, 2017

In this paper, we examine the associations between specific candidate genes (DRD2, DRD4, COMT, bi... more In this paper, we examine the associations between specific candidate genes (DRD2, DRD4, COMT, biallelic and tri-allelic 5HTTLPR, and OXTR) and infant attachment outcomes as main effects and in conjunction with maternal sensitivity. The sample included 200 infants (97 European American, 94 African-American, and 9 biracial) and their mothers. Maternal sensitivity and overtly negative maternal behavior were observed when infants were 6 months and 1 year old in distress-eliciting contexts, attachment was assessed via the Strange Situation at age 1, and DNA samples were collected when children were 2 years old. Consistent with recent research in large samples, there was little evidence that these genes are associated with attachment security, disorganization, or distress as main effects (in additive, dominant, and homozygous models) or in conjunction with maternal sensitivity or overtly negative behavior (primarily dominance models). Furthermore, there was little evidence that associati...

Drug and Alcohol Dependence, 2007

Pharmacology Biochemistry and Behavior, Apr 30, 1985

PloS one, 2016

The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphis... more The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphism has been implicated to moderate the relationship between the experience of stressful life events (SLEs) and depression. Despite numerous attempts at replicating this observation, results remain inconclusive. We examined this relationship in young-adult Non-Hispanic white males and females between the ages of 22 and 26 (n = 4724) participating in the National Longitudinal Study of Adolescent to Adult Health (Add Health) with follow-up information every six years since 1995. Linear and logistic regression models, corrected for multiple testing, indicated that carriers of one or more of the S-alleles were more sensitive to stress than those with two L-alleles and at a higher risk for depression. This relationship behaved in a dose-response manner such that the risk for depression was greatest among those who reported experiencing higher numbers of SLEs. In post-hoc analyses we were not ab...

Biological Psychiatry, Jan 5, 2006

A promoter polymorphism in the serotonin transporter (5HTTLPR) has functional effects on an impor... more A promoter polymorphism in the serotonin transporter (5HTTLPR) has functional effects on an important physiologic process involved in serotonin (5HT) signaling. Despite the fact that variation in the 5HT system has long been implicated in the etiology of aggressive behaviors, only a few association-based studies with mixed results have been reported. We conducted family-based tests of association in a sample of 366 families from which 1187 genotypes of the 5HTTLPR were generated using polymerase chain reaction. Ratings of aggressive behavior were obtained from parents and teachers longitudinally using the Child Behavior Checklist (CBCL) and Teacher Report Form (TRF), instruments widely used in behavioral and psychiatric genetics. Within-family tests suggest an association between the s-allele of the 5HTTLPR and higher aggressive behavior in middle childhood. The strongest association was at age 9 and for an aggregate measure of teacher-rated aggressive behavior. This is the first report of an association analysis of the 5HTTLPR in a general population sample of school-age children. The results provide some support for the hypothesis that the functional effects of the 5HTTLPR s-allele are associated with higher levels of aggressive behavior in middle childhood.

Journal of abnormal psychology, 2015

Depression is a debilitating mental illness with clear developmental patterns from childhood thro... more Depression is a debilitating mental illness with clear developmental patterns from childhood through late adolescence. Here, we present data from the Gene Environment Mood (GEM) study, which used an accelerated longitudinal cohort design with youth (N = 665) starting in 3rd, 6th, and 9th grades, and a caretaker, who were recruited from the general community, and were then assessed repeatedly through semistructured diagnostic interviews every 6 months over 3 years (7 waves of data) to establish and then predict trajectories of depression from age 8 to 18. First, we demonstrated that overall prevalence rates of depression over time, by age, gender, and pubertal status, in the GEM study closely match those trajectories previously obtained in past developmental epidemiological research. Second, we tested whether a genetic vulnerability-stress model involving 5-HTTLPR and chronic peer stress was moderated by developmental factors. Results showed that older aged adolescents with SS/SL gen...

Social Science Research, 2015

Although stressful life events during adolescence are associated with the adoption of unhealthy b... more Although stressful life events during adolescence are associated with the adoption of unhealthy behaviors such as smoking, both social circumstances and physical traits can moderate the relationship. This study builds on the stress paradigm and gene-environment approach to social behavior by examining how a polymorphism in the serotonin transporter gene 5-HTTLPR moderates the effect of life events on adolescent smoking. Tests of interaction hypotheses use data from the Family Transitions Project, a longitudinal study of 7th graders followed for 5years. A sibling-pair design with separate models for the gender composition of pairs (brothers, sisters, or brother/sister) controls for unmeasured family background. The results show that negative life events are significantly and positively associated with smoking. Among brother pairs but not other pairs, the results provide evidence of gene-environment interaction by showing that life events more strongly influence smoking behavior for those with more copies of the 5-HTTLPR S allele.

The Open Family Studies Journal, 2009

This article's objectives are twofold: (a) to disclose the possible distortion of the association... more This article's objectives are twofold: (a) to disclose the possible distortion of the associations found in the reductionist research that prevails in many areas, in order to ensure greater caution and better understanding of such research. (b) To study the associations between family and parental factors and adolescent psychological disorders (PD) according to a systemic model that analyses eight familial factors and eleven parental factors in addition to two nominal ones: culture and the adolescents' sex. The study is based on a data collected from nine countries (1358 male and 1526 female adolescents), regarding two categories of family factors (socio-economic and connectedness) and three categories of parenting factors (control, inconsistency, and rejection) and adolescent psychological disorders (PD). To compare different levels of reductionism, four analyses of the same data were carried out, ranging from an analysis of the associations between each factor and adolescent PD (reductionist), to analysis of the associations between all the factors taken together (systemic) and adolescent PD. In addition, the systemic analysis was carried out among different groups of adolescents according to two nominal variables: culture (western and eastern) and the adolescents' sex (male female). Our results show that in a reductionist analysis most of the family and parental factors have significant associations with adolescents PD, and altogether explain 37.2% of adolescents' PD. Most of these associations were diminished or changed in the systemic analysis and explained only 13.5% of the PD variance. The associations of the more systemic analysis changed again when two nominal factors (culture and sex) were taken into consideration. These findings indicate that reductionist analyses may lead to illusionary associations and that mixed results are an inevitable or even inherent byproduct of reductionist research.

Journal of Studies on Alcohol and Drugs, 2007

Objective-Dopaminergic dysfunction has been hypothesized to play an important role in the etiolog... more Objective-Dopaminergic dysfunction has been hypothesized to play an important role in the etiology of alcohol use disorders. A restriction fragment length polymorphism (RFLP) in the 3' untranslated region (3'UTR) of the DRD2 gene affects gene expression and has been implicated as a risk factor for alcohol dependence. This polymorphism (TaqIA) has been reported as positively associated with alcohol use disorders in case-control samples, but these results have not been replicated in family-based association studies. These mixed results of association between the DRD2 TaqIA polymorphism and alcohol use disorders may be due to differences in sample size, phenotype definition, heterogeneity of the samples and genetic admixture. Method-We conducted tests of association in a sample of 838 adults participating in the National Youth Survey Family Study (NYSFS). We examined whether the DRD2 TaqIA polymorphism was associated with a symptom counts measure of alcohol abuse and dependence derived from the DSM-IV and Craving Withdrawal models. Results-Tests of association were non-significant across each classification system examined. Power calculations suggested these results were despite the ability to detect an effect size of 1%. Conclusions-This study supports other family-based association tests that have reported no association between the DRD2 TaqIA polymorphism and alcohol abuse and dependence.

Background: The Brain Reward Cascade (BRC) is an interaction of neurotransmitters and their respe... more Background: The Brain Reward Cascade (BRC) is an interaction of neurotransmitters and their respective genes to control the amount of dopamine released within the brain. Any variations within this pathway, whether genetic or environmental (epigenetic), may result in addictive behaviors or RDS, which was coined to define addictive behaviors and their genetic components. Methods: To carry out this review we searched a number of important databases including: Filtered: Cochrane Systematic reviews; DARE; Pubmed Central Clinical Quaries; National Guideline Clearinghouse and unfiltered resources: PsychINFO; ACP PIER; PsychSage; Pubmed/Medline. The major search terms included: dopamine agonist therapy for Addiction; dopamine agonist therapy for Reward dependence; dopamine antagonistic therapy for addiction; dopamine antagonistic therapy for reward dependence and neurogenetics of RDS. Results: While there are many studies claiming a genetic association with RDS behavior, not all are scienti...

Developmental pharmacology and therapeutics, 1981

A 3-fold increase in aldehyde dehydrogenase (A1DH) was found in the cytosolic fraction of mouse l... more A 3-fold increase in aldehyde dehydrogenase (A1DH) was found in the cytosolic fraction of mouse liver homogenates during pregnancy. The increase in A1DH activity began at day 10 of pregnancy, peaked at parturition, and declined in a biphasic manner with half-lives of 4.15 and 47.7 days. Enzymes from control (beta A1DH), pregnant (pi A1DH) and phenobarbital-treated (phi AlDH) were partially purified and compared. All had molecular weights of approximately 60,000 daltons. Substrate specificities were similar except that phi A1DH had a lower Km for propionaldehyde than beta or pi and both pi and phi oxidized 4-carboxybenzaldehyde poorly compared to beta. Electrophoretic and thermal denaturation studies showed some similarities between beta and pi, but phi A1DH behaved quite differently. It was concluded that pregnancy caused an increase in one of the A1DHs already present in control mice, while phenobarbital treatment resulted in induction of a unique cytosolic A1DH.

Alcohol and drug research, 1987

The duration of loss of the righting response (sleep time) is often used to assess central nervou... more The duration of loss of the righting response (sleep time) is often used to assess central nervous system sensitivity to ethanol. It has been assumed that there is a threshold concentration of ethanol at which an animal will regain the righting response, and that this level should not change with dose or route of administration of ethanol. Five hypnotic doses of ethanol were given to Long-sleep and Short-sleep mice by intraperitoneal injection. At the time of awakening, blood and brain ethanol levels were measured. It was found that within a line, the animals awoke at the same blood and brain ethanol concentration irrespective of the ethanol dose given. The threshold blood ethanol level was 265 mg% for Long-Sleep males and 484 mg% for Short-Sleep males. These results indicate that there is a threshold value for ethanol, and that this threshold is characteristic for a given mouse line.

The Journal of nutrition, 1989

A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and exper... more A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and experimental animals for reasons that are not known. To determine if mice also develop decreased plasma PLP concentrations during pregnancy, and if plasma PLP levels in pregnancy reflect tissue levels of PLP and pyridoxamine-5'-phosphate (PMP), we measured PLP concentrations in plasma, erythrocytes and whole blood, and liver and brain PLP and PMP in control and pregnant mice. Mice were fed a nonpurified diet containing 8.13 mg pyridoxine-HCl/kg. The PLP analyses were performed in our newly developed apotryptophanase method in which the substrate S-benzyl-L-cysteine is hydrolyzed to benzyl mercaptan, reacted with Ellman's reagent and measured spectrophotometrically. During pregnancy, plasma PLP levels decreased 50% below control levels, but erythrocyte and whole blood PLP levels increased 2.9- and 1.6-fold, respectively. Liver PLP and PMP decreased 25%, in parallel with plasma PLP, but...

The Journal of nutrition, 1990

Plasma pyridoxal 5'-phosphate (PLP) concentrations are considered to be the most reliable sin... more Plasma pyridoxal 5'-phosphate (PLP) concentrations are considered to be the most reliable single indicator of vitamin B-6 nutritional status and are thought to reflect tissue PLP and pyridoxamine 5'-phosphate (PMP) levels. We investigated the relationship between dietary level of pyridoxine hydrochloride (PN-HCl) and concentrations of PLP in blood and PLP and PMP in liver and brain of mice. Female heterogeneous stock mice, 60 to 90 d old, were fed purified diets containing 0.5, 1.0, 2.0, 3.0, 5.0, or 7.0 mg PN-HCl/kg diet for 5 wk. PLP and PMP concentrations were determined by a spectrophotometric apotryptophanase assay. PLP content of plasma, erythrocytes, whole blood, liver and brain and PMP levels in liver and brain were highly correlated with dietary level of PN-HCl (r values ranged from 0.81 to 0.94, n per correlation = 32 to 43). By using the entire range of dietary levels of PN-HCl, both plasma and erythrocyte PLP were found to be significantly correlated with tissue ...

The Journal of nutrition, 1990

Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythroc... more Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythrocyte PLP levels increase threefold over nonpregnant levels. These studies were designed to determine whether changes in the enzymes involved in synthesis and degradation of PLP in blood are altered during pregnancy. We measured net synthesis of PLP in erythrocytes and the activity of enzymes involved in the regulation of plasma and erythrocyte PLP concentration: erythrocyte pyridoxal kinase (PLK) and neutral phosphatase, and plasma and tissue alkaline phosphatase (ALP). Net synthesis of PLP and activities of erythrocyte PLK and neutral phosphatase in erythrocytes remained unchanged during pregnancy. We were unable to detect any dephosphorylation of PLP in erythrocytes of pregnant or nonpregnant mice. Mouse erythrocytes were devoid of ALP activity; neutral phosphatase was inactive with PLP and PLP was an uncompetitive inhibitor of the enzyme. Plasma ALP activity decreased 50% in the pregna...