Publications by authors named "Ian R Gizer"

Binge drinking is a relatively common pattern of alcohol use among youth with normative frequency trajectories peaking in emerging and early adulthood. Frequent binge drinking is a critical risk factor for not only the development of alcohol use disorders (AUDs) but also increased odds of alcohol-related injury and death, and thus constitutes a significant public health concern. Changes in binge drinking across development are strongly associated with changes in impulsive personality traits (IPTs) which have been hypothesized as intermediate phenotypes associated with genetic risk for heavy alcohol use and AUD.

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Article Synopsis
  • Alcohol Use Disorder (AUD) shows varied symptoms, but past studies focused on genetic links without exploring the severity of these symptoms, which this study aims to address.
  • Using a polygenic risk score (PRS) based on data from previous studies, researchers assessed how genetic factors relate to the severity of individual AUD symptoms and overall disorder severity.
  • The findings revealed a strong correlation between genetic and phenotypic severity of AUD symptoms, but the PRS did not uniquely predict individual symptoms outside of overall AUD severity, suggesting a need for future research to examine symptoms individually for better understanding.
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Background: Executive functioning (EF) has been proposed as a transdiagnostic risk factor for externalizing disorders and behavior more broadly, including attention-deficit/hyperactivity disorder (ADHD), aggression, and alcohol use. Previous research has demonstrated both phenotypic and genetic overlap among these behaviors, but has yet to examine EF as a common causal mechanism. The current study examined reciprocal causal associations between EF and several externalizing behaviors using a Mendelian randomization (MR) approach.

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Article Synopsis
  • The study investigates the genetic links between aggression and alcohol use, specifically focusing on how these genetic factors may influence alcohol-related aggression differently.
  • Using polygenic risk scores (PRS) based on genome-wide data, the researchers analyzed the relationship between genetic risks and instances of alcohol-related aggression in two different groups: UCSF Family Alcoholism Study and the National Longitudinal Study of Adolescent to Adult Health.
  • Results showed significant links between genetic risks for alcohol use disorder and aggression in the UCSF sample, but not in the Add Health sample, suggesting varying effects based on the context and type of aggression related to alcohol use.
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Patterns of association with externalizing and internalizing features differ across heroin use and prescription opioid misuse (POM). The present study examined whether heroin use and POM display differential etiologic overlap with symptoms of conduct disorder (CD), adult antisocial behavior (AAB), and major depressive episodes (MDEs), how aggregating heroin use and POM into a single phenotype may bias results, and explored potential sex differences. Seven thousand one hundred and sixty-four individual twins from the Australian Twin Registry (ATR; 59.

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Bipolar disorder (BD) is a heritable mental illness with complex etiology. While the largest published genome-wide association study identified 64 BD risk loci, the causal SNPs and genes within these loci remain unknown. We applied a suite of statistical and functional fine-mapping methods to these loci, and prioritized 17 likely causal SNPs for BD.

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Sensation seeking is bidirectionally associated with levels of alcohol consumption in both adult and adolescent samples, and shared neurobiological and genetic influences may in part explain these associations. Links between sensation seeking and alcohol use disorder (AUD) may primarily manifest via increased alcohol consumption rather than through direct effects on increasing problems and consequences. Here the overlap among sensation seeking, alcohol consumption, and AUD was examined using multivariate modelling approaches for genome-wide association study (GWAS) summary statistics in conjunction with neurobiologically informed analyses at multiple levels of investigation.

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Background: Only a small proportion of individuals who initiate nonmedical use of prescription opioids (NUPO) transition to heroin, suggesting that more nuanced aspects of NUPO may be better indicators of risk for escalating opioid use trajectories. This study leveraged panel data to identify NUPO typologies based on NUPO characteristics associated with opioid risk trajectories (route of administration, motives) and compared rates of heroin initiation at follow-up across typologies.

Methods: Latent class analyses were run among respondents with no history of heroin use from the Monitoring the Future Panel Study (base year N=10,408) at modal ages 18, 19/20, 21/22, 23/24, and 25/26.

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Background: Dual-systems models, positing an interaction between two distinct and competing systems (i.e. top-down self-control, and bottom-up reward- or emotion-based drive), provide a parsimonious framework for investigating the interplay between cortical and subcortical brain regions relevant to impulsive personality traits (IPTs) and their associations with psychopathology.

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Sensation seeking is bidirectionally associated with levels of alcohol consumption in both adult and adolescent samples and shared neurobiological and genetic influences may in part explain this association. Links between sensation seeking and alcohol use disorder (AUD) may primarily manifest via increased alcohol consumption rather than through direct effects on increasing problems and consequences. Here the overlap between sensation seeking, alcohol consumption, and AUD was examined using multivariate modeling approaches for genome-wide association study (GWAS) summary statistics in conjunction with neurobiologically-informed analyses at multiple levels of investigation.

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Article Synopsis
  • A study with 7,164 twins from the Australian Twin Registry explored the genetic and environmental influences on prescription opioid misuse (POM) and heroin use, revealing their differences.
  • The analysis used two models to partition the variance in drug use, showing that POM had significant drug-specific genetic influences, while heroin did not display any genetic variation specific to its use.
  • The findings suggest that the misuse of prescription medications relates to genetic factors that differ from those affecting heroin use, indicating a complex relationship between drug types and their misuse.
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Objective: Examine the nature of the relationship between adolescent polysubstance use and high school noncompletion.

Method: Among a sample of 9,579 adult Australian twins (58.63% female, = 30.

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Background: Dual-systems models provide a parsimonious framework for understanding the interplay between cortical and subcortical brain regions relevant to impulsive personality traits (IPTs) and their associations with psychiatric disorders. Despite recent developments in multivariate analysis of genome-wide association studies (GWAS), molecular genetic investigations of these models have not been conducted.

Methods: Using extant IPT GWAS, we conducted confirmatory genomic structural equation models (GenomicSEM) to empirically evaluate dual-systems models of the genetic architecture of IPTs.

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Background: Prescription opioid misuse (POM) is often implicated in heroin initiation, despite evidence that POM does not predict heroin initiation any better than other drug use. Additionally, prescription misuse and illicit use behaviors tend to respectively "cluster" together. This study aimed to test a series of theory-driven factor models to explore how POM and heroin use are situated within the broader constellation of drug use that typically occurs alongside opioid (mis)use.

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Introduction: Genome-wide association studies (GWAS) have played a critical role in identifying many thousands of loci associated with complex phenotypes and diseases. This has led to several translations of novel disease susceptibility genes into drug targets and care. This however has not been the case for analyses where sample sizes are small, which suffer from multiple comparisons testing.

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Genes associated with educational attainment may be related to or interact with adolescent alcohol, tobacco and cannabis use. Potential gene-environment interplay between educational attainment polygenic scores (EA-PGS) and adolescent alcohol, tobacco, and cannabis use was evaluated with a series of regression models fitted to data from a sample of 1871 adult Australian twins. All models controlled for age, age, cohort, sex and genetic ancestry as fixed effects, and a genetic relatedness matrix was included as a random effect.

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Background And Aims: Previous studies have demonstrated associations between substance use and reduced educational attainment; however, many were unable to account for potential confounding factors like genetics and the rearing environment. In the few studies that controlled for these factors, the substances assessed were limited to alcohol, cannabis, and tobacco. To address these limitations, we examined the relationship between adolescent use of seven kinds of substances, the number of additional substances used, and high school noncompletion within a large sample of Australian twins.

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Background: Prior studies have established the importance of genetic contributions to the etiology of alcohol dependence (AD), and suggested an early onset of alcohol use represents an initial marker of this genetic risk, which is associated with a more rapid progression to AD and increased risk for AD itself. Building on prior work, the current study examined whether the additive effects of AD risk variants predicted the rate of progression to AD from the onset of regular drinking, a drinking milestone with high clinical relevance to AD prevention.

Methods: Data from 1501 European-ancestry adults from the University of California - San Francisco Family Alcoholism Study were used to examine whether polygenic risk scores for AD (PRS) and age-at-onset of regular drinking contributed uniquely to the likelihood of having a lifetime AD diagnosis and the rate of progression from regular drinking to AD.

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Background And Aims: Previous research has demonstrated phenotypical associations between disordered gambling (DG) and Big 5 personality traits, and a twin study suggested that shared genetic influences accounted for a substantial portion of this relation. The present study examined associations between DG and polygenic scores (PSs) for Big 5 traits to measure the shared genetic underpinnings of Big 5 personality traits and DG.

Design: Zero-inflated negative binomial regression models estimated associations between Big 5 PSs and past-year and life-time assessments of DG in a longitudinally assessed population-based birth cohort.

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Article Synopsis
  • Bipolar disorder has a genetic basis and complex causes; a large study compared nearly 42,000 bipolar patients with over 371,000 healthy controls, revealing 64 genomic regions linked to the disorder.
  • The findings showed that risk-related genes are heavily associated with brain functions, particularly in areas like the prefrontal cortex and hippocampus, and they include targets for various medications.
  • The research also distinguished between bipolar disorder types I and II, revealing a close genetic relationship and highlighting 15 specific genes that could lead to new treatment options and further investigations.
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Background: Prior research on alcohol consumption and pain has yielded inconsistent results regarding the directionality of effects for both consumption-to-pain and pain-to-consumption relations. The present study sought to examine directionality of these relations by testing bidirectional longitudinal associations between consumption and pain interference, a crucial aspect of pain that captures pain-related disability and has been regarded as a valuable measure of treatment outcome. In addition, this study explored possible moderation of these bidirectional longitudinal associations by gender and alcohol use disorder (AUD) symptomatology.

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Objective: Epidemiological estimates suggest that nearly half of individuals diagnosed with alcohol use disorder will be diagnosed with another mental health disorder, with strong associations involving other externalizing disorders. Molecular genetic studies investigating the relation between alcohol use disorder and externalizing behaviors (e.g.

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Cannabis use has been rising despite recognition of the negative consequences associated with heavy use. The severity of these consequences has been shown to differ across racial/ethnic groups, even when controlling for consumption levels. The present study conducted an item response theory (IRT) analysis of the Cannabis Use Disorders Identification Test (CUDIT) to better understand the patterns of problematic cannabis use and their relation with other substance use across ethnic groups in the Healthy Life in an Urban Setting (HELIUS) study.

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Disordered gambling (DG) is a rare but serious condition that results in considerable financial and interpersonal harms. Twin studies indicate that DG is heritable but are silent with respect to specific genes or pathways involved. Existing genomewide association studies (GWAS) of DG have been substantially underpowered.

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Individuals with schizophrenia have higher lifetime rates of substance use disorders than the general population, and research suggests high comorbidity rates may be partially explained by shared genetic influences related to common underlying etiology. Moreover, deficits in executive functions are thought to be central to the diagnosis of schizophrenia and are likewise associated with alcohol and tobacco use. The current study examined the associations between schizophrenia polygenic risk scores and tobacco and alcohol use and the mediation of these associations by executive function sub-domains.

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