James MacKillop

McMaster University | McMaster · Department of Psychiatry and Behavioural Neurosciences

Delayed reward discounting (DRD) is defined as the extent to which person favors smaller rewards that are immediately available over larger rewards available in the future. Higher levels of DRD have been identified in individuals with a wide range of clinical disorders. Although there have been studies adopting larger samples and using only gray ma...

https://www.elsevier.com/books/handbook-of-cognitive-behavioral-therapy-by-disorder/martin/978-0-323-85726-0

Background and aims Problem gambling and tobacco use are highly comorbid among adults. However, there are few treatment frameworks that target both gambling and tobacco use simultaneously (i.e., an integrated approach), while also being accessible and evidence-based. The aim of this two-arm open label RCT was to examine the efficacy of an integrate...

Disgust sensitivity refers to how unpleasant a disgusting experience is to an individual and is involved in the development of many psychiatric conditions. Given its link with food ingestion, there is an interest in understanding how an individual’s susceptibility to disgust relates to dietary habits. One possible mechanism giving rise to this asso...

Background: Fetal alcohol spectrum disorder (FASD) resulting from prenatal alcohol exposure (PAE) is a common neurodevelopmental disorder, but substantial interindividual heterogeneity complicates timely and accurate assessment, diagnosis, and intervention. The current study aimed to identify classes of children and adolescents with PAE assessed f...

Background: Despite limited clinical evidence of its efficacy, cannabis use has been commonly reported for the management of various mental health concerns in naturalistic field studies. The aim of the current study was to use machine learning methods to investigate predictors of perceived symptom change across various mental health symptoms with...

Introduction: Cannabis is used for medical and recreational purposes and may result in cannabis use disorder (CUD). This study explored the prevalence of cannabis use disorder and other psychiatric comorbidities among inpatients undergoing treatment for substance use disorder who reported medical cannabis use at admission. Methods: We assessed C...

Delayed reward discounting (DRD) refers to the extent to which an individual devalues a reward based on its delay in time and has been linked to a wide variety of health behaviors. Because it is commonly measured using monetary rewards, income is typically used as a covariate to adjust for a person's socioeconomic status. Standard financial income...

BACKGROUND Deep transcranial magnetic stimulation (dTMS) is a novel non-invasive treatment option for psychiatric and cognitive disorders, including obsessive-compulsive disorder, substance use disorder, major depressive disorder (MDD), and Alzheimer’s Disease. With the use of Hesed-coil (H-coil) devices, dTMS can stimulate deeper regions of the br...

Given the well-established relationship between alcohol and internalizing symptoms, potential increases in depression and anxiety during the COVID-19 pandemic may lead to increases in alcohol consumption and binge drinking. This study examines this association from before to during two phases of the pandemic in a cohort of Canadian youth. We used l...

Alcohol is one of the most widely consumed psychoactive drugs globally. Hazardous drinking, defined by quantity and frequency of consumption, is associated with acute and chronic morbidity. Alcohol use disorders (AUDs) are psychiatric syndromes characterized by impaired control over drinking and other symptoms. Contemporary aetiological perspective...

Background: The COVID-19 pandemic has been associated with major psychosocial disruptions and there is particular concern for individuals with substance use disorders. Objectives: This study characterized the psychosocial and experiential impacts of the pandemic on individuals seeking alcohol use disorder (AUD) recovery, including pandemic impacts...

Background Individuals with substance use disorders (SUDs) have highly heterogeneous presentations and identifying more homogeneous subgroups may foster more personalized treatment. This study used SUD and other psychiatric indicators to characterize latent subgroups of patients in a large inpatient addiction treatment program. The resulting subgro...

Risky decision-making is a common, heritable endophenotype seen across many psychiatric disorders. Its underlying genetic architecture is incompletely explored. We examined behavior in the Balloon Analogue Risk Task (BART), which tests risky decision-making, in two independent samples of European ancestry. One sample (n=1138) comprised healthy part...

Introduction The COVID-19 pandemic has had a tremendous negative effect on the mental health and well-being of Canadians. These mental health challenges are especially acute among vulnerable Canadian populations. People living in Canada’s most populous province, Ontario, have spent prolonged time in lockdown and under public health measures and the...

Background High rates of substance misuse during emerging adulthood require developmentally appropriate clinical programs. Objectives This work outlines the development of an evidence-informed emerging adult outpatient substance use program, quality improvement process and protocol, and 1-year program insights. Methods Literature reviews, program...

Background and aims: The Marijuana Purchase Task (MPT) is increasingly used to measure cannabis reinforcing value and has potential utility for cannabis etiological and regulatory research. This meta-analysis sought to evaluate for the first time the MPT's concurrent validity in relation to cannabis involvement. Methods: Electronic databases and...

While several studies have examined how class time and internship responsibilities impact demand for alcohol in undergraduate samples, no study has examined this question using more universally applicable responsibilities with a sample of community adults. Therefore, the aim of this study was to examine the impact of a range of next-day responsibil...

Introduction Disruption of cortical gray matter and white matter tracts are well‐established markers of alcohol use disorder (AUD), but less is known about whether similar differences are present in intracortical myelin (ICM, i.e., highly myelinated gray matter in deeper cortical layers). The goal of this study was to provide initial proof‐of‐conce...

Introduction Measurement-Based Care (MBC) is an emerging healthcare model with a number of potential advantages over traditional approaches for the treatment of substance use disorder (SUD). Despite SUD treatment programs being theoretically well suited for the implementation of MBC, its uptake has been minimal, which in turn limits further researc...

Objective Inpatient treatment programs for substance use disorders (SUDs) typically have an abstinence policy for patients, but unsanctioned substance use nonetheless takes place and can have significant negative clinical impacts. The current study sought to understand this problem from a patient perspective and to develop strategies for improved c...

Purpose To date, there are few longitudinal studies on the COVID-19 pandemic's ongoing impact on youth drinking. This study examines the changes in drinking during two phases of the pandemic in a sample of Canadian youth. Methods We used four-year longitudinal data from the COMPASS study, including 14,085 secondary school students from Quebec and...

Background While substance use and mental health symptoms commonly co-occur among adolescents, few population-level studies have examined profiles of co-occurrence to inform tailored prevention and early intervention. Methods A multilevel latent profile analysis was conducted on a representative sample of 11,994 students in 68 secondary schools to...

While the neuroanatomical correlates of impulsivity in youths have been examined, there is little research on whether those correlates are consistent across childhood/adolescence. The current study uses data from the age 11/12 (N = 7083) visit of the Adolescent Brain Cognitive Development (ABCD) Study to investigate the replicability of the neuroan...

Objective: Smoking is a leading cause of avoidable death, with the best cessation treatments yielding only 10-30% abstinence. Limited neurocognitive research is available on the best predictor of cessation: addiction severity. We investigated whether smoking severity is associated with stronger resting functional connectivity and cognitive function...

OBJECTIVE Few studies have examined cannabis motives in adults and, although associations between cannabis use and psychiatric conditions are well documented, there has been limited investigation of the intersection of cannabis use, cannabis motives, and psychopathology. In a sample of community adults, the present study examined cannabis motives i...

Background: Alcohol use impairs psychosocial and neurocognitive development and increases the vulnerability of youth to academic failure, substance use disorders, and other mental health problems. The early onset of alcohol use in adolescents is of particular concern, forecasting substance abuse in later adolescence and adulthood. To date, evidence...

BACKGROUND Alcohol use impairs psychosocial and neurocognitive development and increases youth vulnerability to academic failure, substance use disorder and other mental health problems. Early adolescent alcohol use onset is of particular concern, forecasting substance abuse in later adolescence and adulthood. Evidence to date suggests that youth i...

Objective Although there is growing interest in medically authorized cannabis for chronic pain, little is known about patients’ perspectives. We explored perceptions of people living with chronic pain regarding benefits and concerns surrounding their use of cannabis for therapeutic purposes. Setting A hospital-based clinic in Hamilton and two comm...

Objective: Problematic internet use (PIU) is characterized by excessive or poorly controlled internet use resulting in impairment or distress. PIU is most prevalent during emerging adulthood, a period marked by an increase in psychiatric disorders, including substance use disorders (SUDs). In a sample of high-risk emerging adults, the aim of this...

Rationale Alcohol use disorder (AUD) is associated with steeper delay discounting rates; however, it is unknown whether substance co-use, particularly cannabis use, has an additive effect on discounting rates among heavy drinkers. Furthermore, it is unclear whether substance co-use and delay discounting are independently associated with AUD severit...

Background The coronavirus disease 2019 (COVID-19) pandemic has imposed enormous adversity worldwide. Public health guidelines have been a first line of defense but rely on compliance with evolving recommendations and restrictions. This study sought to characterize adherence to and perceptions of public health guidelines over a one-year timeframe d...

Background SARS-CoV-2 infection is believed to adversely affect the brain, but the degree of impact on socially relevant cognitive functioning and decision-making is not well-studied, particularly among those less vulnerable to age-related mortality. The current study sought to determine whether infection status and COVID-19 symptom severity are as...

Delayed reward discounting (DRD) is a form of decision-making reflecting valuation of smaller immediate rewards versus larger delayed rewards, and high DRD has been linked to several health behaviors, including substance use disorders, attention-deficit/hyperactivity disorder, and obesity. Elucidating the underlying neuroanatomical factors may offe...

Background Little is known about cannabis use for insomnia in individuals with depression, anxiety, and comorbid depression and anxiety. To develop a better understanding of distinct profiles of cannabis use for insomnia management, a retrospective cohort study was conducted on a large naturalistic sample. Methods Data were collected using the med...

Background: Longitudinal research on COVID-19 impacts on drinking is scarce and largely restricted to comparing drinking levels before and after the introduction of COVID mitigation measures. This brief snapshot of behavior ignores the extended pre-COVID drinking trajectory, which may be decreasing increasing, or remaining stable over time. Behavio...

*(JOURNAL ARTICLE NOW AVAILABLE https://doi.org/10.1037/pha0000609). While several studies have examined how class time and internship responsibilities impact demand for alcohol in undergraduate samples, no study has examined this question using more broadly applicable responsibilities with a sample of community adults. Therefore, the aim of this s...

In March 2020, restrictions on in-person gatherings were introduced due to the coronavirus disease (COVID-19) pandemic, requiring alcohol use disorder (AUD) recovery resources to migrate to virtual platforms. This study investigated how these restrictions impacted recovery attempts and explored participant experiences with virtual resources using a...

Objectives: To examine the proportion of individuals using cannabis for medical purposes who reported nonmedical use of cannabis after it became legal to do so. Materials and Methods: We acquired data from the Population Assessment for Tomorrow's Health, the Cannabis Legalization Surveillance Study on a subpopulation of participants residing in Ham...

Objective: Adverse childhood experiences (ACEs) and lifetime traumatic events are closely linked to development of comorbid psychiatric symptoms and substance use. Although research shows the risk for psychiatric and substance use comorbidity conferred by early adversity, most studies have not modeled multivariate symptom patterns that include pos...

Background: We conducted a longitudinal study to examine person-centered heterogeneity in problem drinking risk during the 2019 Coronavirus disease (COVID-19) pandemic. We aimed to differentiate high- from low-risk subgroups of drinkers during the pandemic, to report on the longitudinal follow-up of the baseline sample reported in Wardell et al. (...

Introduction: It remains unclear whether electronic cigarette (e-cigarette) use promotes persistent combustible tobacco use or smoking discontinuation over time. Alcohol use is associated with greater risk of adverse health effects of tobacco, and higher likelihood of e-cigarette use, making drinkers a high priority subpopulation. This study exami...

Polysubstance use (PSU) is the use of more than one psychoactive substance simultaneously or independently, and occurs in roughly half of individuals who seek treatment for substance use. The current study sought to use resting state functional connectivity (rs-FC) to examine functional connectivity in participants who report using multiple or sing...

Background Impulsivity is a multidimensional heritable phenotype that broadly refers to the tendency to act prematurely and is associated with multiple forms of psychopathology. Methods We performed genome-wide association studies ( GWAS ) of eight impulsive personality traits from the Barratt Impulsiveness Scale and the short UPPS-P Impulsive Per...

Background: The Research Domain Criteria (RDoC) approach proposes a novel psychiatric nosology using transdiagnostic dimensional mechanistic constructs. One candidate RDoC indicator is delay discounting (DD), a behavioral economic measure of impulsivity, based predominantly on studies examining DD and individual conditions. The current study sough...

Rationale Pharmacotherapies are an important clinical strategy for treating alcohol use disorder and an understanding of their functional mechanisms can inform optimal use. Behavioral economics provides a translational platform that may advance our understanding of the motivational impacts of pharmacotherapies. Objectives This secondary analysis s...

Background: Recreational cannabis legalization has become more prevalent over the past decade, with recreational cannabis now legal in 13 U.S. states and nationally in Uruguay, Canada, and Malta. At the same time, there is evidence for increasing rates of cannabis use and consequences from use (i.e., crime and motor vehicle accidents) among some ag...

Delayed reward discounting (DRD) refers to the extent to which an individual devalues a reward based on a temporal delay and is known to be elevated in individuals with substance use disorders and many mental illnesses. DRD has been linked previously with both features of brain structure and function, as well as various behavioral, psychological, a...

Background Findings have been mixed as to whether brief intervention (BI) is appropriate and effective for individuals with more severe alcohol use problems. Motivation to change drinking has been supported as a mechanism of behavior change for BI. This exploratory study examined aspects of motivation as mechanisms of clinical response to BI and al...

Executive functions (EF) deficits are hypothesized to be a core contributor to hoarding symptoms. EF have been studied in adult hoarding populations, but studies in youth are lacking. The current study compared multiple EF subdomains between youth with obsessive-compulsive disorder (OCD) and youth with OCD and hoarding symptoms. Forty youth (8–18 y...

Introduction Valid multi-faceted measurement of motivation for substance use disorder (SUD) treatment is needed to help inform treatment approaches and predict outcomes. This study examined evidence of validity for the Treatment Entry Questionnaire (TEQ-9). Methods Data represented individuals entering inpatient SUD treatment (n=1455). We used con...

Background The prevalence of alcohol use disorder (AUD) is estimated to be ten times higher amongst individuals in the criminal justice system compared to the general population. Alcohol use is also one of the strongest modifiable risk factors for recidivism. One intervention that has been shown to be effective in reducing alcohol consumption in th...

This economic evaluation examines national retail sales of alcohol and cannabis before and during the COVID-19 pandemic in Canada.

Background Insomnia is a prevalent condition that presents itself at both the symptom and diagnostic levels. Although insomnia is one of the main reasons individuals seek medicinal cannabis, little is known about the profile of cannabinoid use or the perceived benefit of the use of cannabinoids in daily life. Objective We conducted a retrospective...

Background Longitudinal studies examining the impact of changes in COVID-19 pandemic-related stressors and experiences, and coping styles on the mental health trajectory of employed individuals during the lockdown are limited. The study examined the mental health trajectories of a sample of employed adults in Hamilton, Ontario during the initial lo...

Objective: The Young Adult Alcohol Consequences Questionnaire (YAACQ) was designed to measure the various domains of alcohol-related problems experienced by emerging adults (EAs), but has primarily been used in college samples and it remains unclear whether the psychometric properties of the YAACQ function similarly in racially and economically di...

Aims: Contemporary theories of attention-deficit/hyperactivity disorder (ADHD) and alcohol use disorder (AUD) emphasize core dysfunctions in reward-related processes and behaviors as pathognomonic characteristics. However, to date, it is unclear which domains of reward functioning are unique to ADHD versus AUD symptom dimensions, and which represe...

As of 2019, 34.1 million adults in the United States smoke cigarettes. People who smoke and who are partnered with other smokers (i.e., dual-smoker couples [DSCs]) represent an estimated two-thirds of U.S. smokers. DSCs face unique obstacles to quitting, are less likely to try to quit, and are more likely to relapse during a quit attempt. Although...

Background There are concerns that the COVID-19 pandemic may increase drinking, however most accounts to date are cross-sectional studies of self-attributions about alcohol-related impacts and the accuracy of those perceptions has not been investigated. The current study examined the correspondence between self-attributions of pandemic-related chan...

Objective: Research conducted with young adults has consistently identified cannabis use motives as a predictor for cannabis use and problems, but comparatively few studies have examined cannabis motives in adult samples. Furthermore, although substantive evidence has identified links between cannabis use and psychiatric conditions, limited researc...

LAY SUMMARY Medical cannabis is increasingly used by Canadian Veterans to manage chronic pain; however, the benefits and harms are uncertain. This commentary summarizes a recent guideline that found small to very small benefits of medical cannabis for pain relief, physical functioning and sleep quality, and evidence for a small to very small increa...

Background To determine: (a) the feasibility and acceptability of administering a standardized electronic assessment of substance use and other mental health concerns to youth admitted to an inpatient psychiatric unit, and (b) the prevalence and clinical correlates of substance use in this sample. Methods The sample included 100 youth between the...

Objective: In March 2020, restrictions on in-person gatherings were introduced due to the COVID-19 pandemic. As a result, integral alcohol use disorder (AUD) recovery resources migrated to virtual platforms. Given the importance of these resources for maintaining recovery, this study investigated how these restrictions impacted recovery attempts an...

Background COVID-19 vaccines have been approved for use in Canada since December 2020. However, data about factors associated with vaccine hesitancy and the impact of mental health and/or substance use (MHSU) issues on vaccine uptake are currently not available. The goal of this study was to explore factors, particularly MHSU factors, that impact C...

Background: COVID-19 is a global pandemic and vaccination efforts may be impeded by vaccine hesitancy. The present study examined willingness to receive a COVID-19 vaccine, the associated reasons for willingness/unwillingness, and vaccine safety perceptions in a cross-sectional assessment of community adults in Ontario. Methods: One thousand three...

Obesity has been variously linked to differences in brain functional connectivity in regions associated with reward, emotional regulation and cognition, potentially revealing neural mechanisms contributing to its development and maintenance. This systematic review summarizes and critically appraises the existing literature on differences in resting...

During the COVID-19 pandemic, people may use substances like cannabis for enhancement or coping purposes. Behavioral economic demand for a substance is a key determinant of its use and misuse and can be measured via hypothetical purchase tasks. Previous research suggests that motivations to use a substance play a mediational role between elevated s...

Rationale There is increasing interest in and evidence for the negative impacts of cannabis use in cognitive performance and symptoms of attention-deficit/hyperactivity disorder (ADHD), with age of first cannabis use as a potential amplifier of these associations. However, the existing literature is inconsistent, which may be due to methodological...

RationaleExposure to adverse life experiences (ACEs) is robustly associated with problematic alcohol and other drug use. In addition, both ACEs and substance use have been independently associated with impulsivity.Objective To examine whether impulsivity is implicated in the link between ACE and adult substance use in two samples.Methods The primar...

Objective To evaluate the associations between cannabis use and neurocognitive functioning, including self-reported attention deficit hyperactivity disorder (ADHD) symptoms, in a large sample of emerging adults (ages 21–25) using a cross-sectional design. A secondary objective was to examine age of cannabis initiation as a moderator. Methods Parti...