Marie-Pierre Sylvestre

• PhD Biostatistics (McGill University)
• Professor (Associate) at Université de Montréal

INTRODUCTION The apolipoprotein E (APOE) ɛ4 allele is a well‐established risk factor for neurocognitive impairment (NCI), with varying impacts between men and women. This study investigates the distinct roles of sex and gender in modifying APOE ɛ4–related NCI. METHODS Biological sex was inferred from sex chromosomes, and a femininity score (FS) wa...

To describe mental health indicators according to regular (i.e., weekly or daily) alcohol, cannabis, and/or nicotine use in a population-based sample of young adults. Data for 733 participants (mean age = 30.6 years) were drawn from cycle 23 of the ongoing Nicotine Dependence In Teens study, Montreal, Canada. The associations between (i) number of...

Objective: Growing evidence suggests that higher levels of psychological well-being indicators (e.g., emotional vitality, positive mental health) are related to lower cardiometabolic risk. Healthy lifestyle habits (e.g., physical activity) may underpin this association. However, most studies evaluating the association between psychological well-bei...

Background Tobacco use is a strong risk factor for premature mortality and morbidity. We assessed the feasibility of screening and recruiting participants for a randomized controlled trial (RCT) of a facilitated referral intervention to promote smoking and vaping cessation among parents and children (CanCEASE). Methods We conducted a pilot RCT of C...

Self-compassion comprises treating oneself non-judgementally with kindness and understanding during life challenges. Our aim was to identify, from among a diverse set of sociodemographic, lifestyle behavioural, psychological, family/peer social influence, and health indicators, factors associated with low self-compassion in a population-based sampl...

To examine the associations between food security status and dietary patterns among first-time food-aid users. From September 2018 to January 2020, a sample of 1001 newly registered food-aid users from 106 community-based food donation organizations were recruited across urban, rural, and peri-urban areas in four administrative regions of the provi...

Objective: To describe the natural course of exergaming among young adults and identify predictors of sustained exergaming. Methods: To describe the natural course, we retained 592 participants from an ongoing longitudinal study with complete data on exergaming at four time points over 12-13 years between 2010-12 and 2023 (i.e., T1-T4 at mean ages...

Causal variable selection in time-varying treatment settings is challenging due to evolving confounding effects. Existing methods mainly focus on time-fixed exposures and are not directly applicable to time-varying scenarios. We propose a novel two-step procedure for variable selection when modeling the treatment probability at each time point. We...

Importance How epilepsy may promote cardiovascular disease remains poorly understood. Objective To estimate the odds of new-onset cardiovascular events (CVEs) over 6 years in older people with vs without epilepsy, exploring how enzyme-inducing antiseizure medications (EIASMs) and traditional cardiovascular risk factors mediate these odds. Design,...

Background Young adults face unique vulnerabilities during major life disruptions like the COVID-19 pandemic. The pandemic contributed to increases in mental health challenges and substance use among young adults. This study explores the experiences of young adults who increased their cannabis use during the pandemic. Methods Participants were rec...

Background Multiple sclerosis (MS) is an inflammatory and degenerative disease of the central nervous system. More than 90,000 Canadians are affected; a cure is yet to be found. Available treatments to manage the disease course are only partially effective. For many years, persons with MS (PwMS) have used cannabis to relax, to reduce pain and spast...

Purpose. We explored how team sport participation during adolescence may have prepared emerging adults to use physical activity (PA) as a coping strategy during the COVID-19 pandemic and therefore protect their mental health. Methods. MATCH study participants reported their involvement in team sports from age 11 to 18. At age 20, in the context of...

Background Few studies have compared different measures of frailty for predicting adverse outcomes. It remains unknown which frailty measurement approach best predicts healthcare utilization such as hospitalization and mortality. Aims This study aims to compare three approaches to measuring frailty—grip strength, frailty phenotype, and frailty ind...

Background Active transportation (AT) and free play (FP) are the primary ways in which children engage in unstructured physical activity in cities, with independent mobility (IM) gaining increased attention as a potential precursor of AT and FP. However, current trends show that children are engaging in less FP and AT, and have less IM, than previo...

Background: Few longitudinal studies have investigated the role of weight-loss attempts or weight-related stress on body image during childhood. We examined whether weight-loss attempts and weight-related stress are associated with weight misperception and body dissatisfaction across childhood and adolescence. Methods: Data were drawn from the Queb...

Time-varying confounding is a common challenge for causal inference in observational studies with time-varying treatments, long follow-up periods, and participant dropout. Confounder adjustment using traditional approaches can be limited by data sparsity, weight instability and computational issues. The Nicotine Dependence in Teens (NDIT) study is...

We describe binge drug injection in a longitudinal cohort study of people who inject drugs (PWID) in Montreal, Canada (eligibility: age ≥ 18, past-6-month injection drug use; follow-up: 3-monthly interviews). Bingeing was defined as injecting large quantities of drugs over a limited period, until participants ran out or were unable to continue, in...

Introduction We examined whether factors identified as associated with cannabis use at age 14 to 16 years are also associated with ever use at age 12. Methods Participants in the AdoQuest study (n = 1852) were recruited in 2005 from among Grade 5 students in 29 French-language elementary schools in Montréal, Canada. Self-report data were collected...

Purpose This study aimed to identify opioid consumption trajectories among persons living with chronic pain (CP) and put them in relation to patient‐reported outcomes 6 months after initiating multidisciplinary pain treatment. Methods This study used data from the Quebec Pain Registry (2008–2014) linked to longitudinal Quebec health insurance data...

Background While considerable research has been conducted on household food insecurity (HFI), little research has examined the effects of food donation programs on users’ living conditions. The Pathways study was established to investigate the long-term effects of food donation programs on food insecurity as well as other critical outcomes, such as...

Introduction. Despite heightened risk of cardiovascular disease (CVD) among individuals with type 1 diabetes, few studies in this population have investigated the development of CVD using early markers in adolescence. We compared risk factors (blood pressure (BP) and dyslipidemia) and early markers of CVD between adolescents with and without type 1...

Purpose: Half of adolescents are trying to change their weight and body-related self-conscious emotions may influence these intentions. We estimated associations between body-related shame, guilt, embarrassment, envy, authentic pride, and hubristic pride and weight control status (trying to maintain, lose, or gain weight) throughout adolescence in...

Background: Exergaming may be an important option to support an active lifestyle during the COVID-19 pandemic. Objective: The objectives of this study were to: (i) explore whether change in exergaming status (stopped, started, stable and never exergamed) from before to during the pandemic related to change in walking or moderate-to-vigorous physica...

Background: Mendelian randomization (MR) studies investigating determinants of blood pressure (BP) do not account for antihypertensive medication consistently, which may explain discrepancies across studies. We performed an MR study of the association between body mass index (BMI) and systolic BP (SBP) using five methods to account for antihyperte...

Background Though rates of tobacco smoking have decreased consistently over the past 3 decades, cigarette use remains the top preventable cause of premature death in North America. The Clinical Effort Against Secondhand Smoke Exposure (CEASE) is a medical clinic-based intervention that systematically screens parents for tobacco use and offers them...

BACKGROUND Though rates of tobacco smoking have decreased consistently over the past 3 decades, cigarette use remains the top preventable cause of premature death in North America. The Clinical Effort Against Secondhand Smoke Exposure (CEASE) is a medical clinic-based intervention that systematically screens parents for tobacco use and offers them...

Objective: Quitting smoking by the mid-30 s conveys important health benefits. Yet, although many smokers attempt to quit, few succeed. Identification of the characteristics of adolescent smokers most likely to continue smoking between ages 30 and 40 could help target early cessation efforts. Our objectives in this study were to (i) describe the c...

Background: Monitoring food intake and physical activity (PA) using tracking applications may support behavior change. However, few longitudinal studies identify the characteristics of young adults who track their behavior, findings that could be useful in designing tracking-related interventions. Our objective was to identify predictors of past-y...

Introduction Nous avons vérifié si les facteurs connus pour être associés à la consommation de cannabis entre 14 et 16 ans sont aussi associés au fait d’avoir déjà consommé du cannabis à l’âge de 12 ans. Méthodologie Les participants à l’étude AdoQuest (n = 1 852) ont été recrutés en 2005 parmi les élèves de 5e année de 29 écoles primaires francop...

Introduction: While considerable research has been conducted on household food insecurity (HFI), little research has examined the effects of food donation programs on users’ living conditions. The Pathways study was established to investigate the long-term effects of food donation programs on food insecurity as well as other critical outcomes, such...

Background Uncertainty remains regarding the causal effect of physical activity and sedentary behaviours on the development of type 2 diabetes in children. We aimed to estimate average treatment effects of physical activity and sedentary behaviours on risk of type 2 diabetes in individuals who are at risk during childhood and adolescence. Methods...

Background The endocannabinoid system is implicated in psychiatric disorders and drug dependence. Within this system, fatty acid amide hydrolase (FAAH) metabolizes endocannabinoids. Individuals with A-group genotypes (C/A or A/A) of a common FAAH variant (rs324420; C>A; Pro129Thr) have slower enzymatic activity compared to C-group individuals (C/C...

We documented changes in depressive and anxiety symptoms from before to during the COVID-19 pandemic among young adults and investigated whether changes differed across participant characteristics. Data were available in an investigation of 1294 grade 7 students recruited in 1999–2000. For this analysis, we used data collected pre-pandemically in 2...

BACKGROUND Exergaming may be an important option to support an active lifestyle during the COVID-19 pandemic. OBJECTIVE The objectives of this study were to: (i) explore whether change in exergaming status (stopped, started, stable and never exergamed) from before to during the pandemic related to change in walking or moderate-to-vigorous physical...

Purpose The association between stressful life events and depressive symptoms is well established, but the role of coping style in this association is less clear. We examined whether problem-focused, emotion-focused or avoidant coping style mediated and/or moderated the association in young adults. Methods Data were drawn from a 20-year longitudina...

Background Group-based trajectory modelling (GBTM) is increasingly used to identify subgroups of individuals with similar patterns. In this paper, we use simulated and real-life data to illustrate that GBTM is susceptible to generating spurious findings in some circumstances. Methods Six plausible scenarios, two of which mimicked published analyse...

Purpose: Commonly held hypotheses in practice suggest that compared to single-sport participation, multi-sport participation is associated with higher physical activity (PA) levels and health benefits in the long term. To verify this in the general population, we identified sport participation trajectories during adolescence and examined their ass...

Physical activity (PA) motives are associated with both moderate‐to‐vigorous intensity PA (MVPA) and mental health. Studies examining whether PA motives relate directly to mental health or indirectly through MVPA are lacking. This study examined the direct effect of five PA motives (i.e., enjoyment, competence, fitness, social, appearance) on menta...

Introduction We assessed change in substance use from before to during the COVID-19 pandemic in young adults and identified factors associated with initiation/increase in use. Methods The sample comprised young adults from a longitudinal investigation of 1294 youth recruited at ages 12-13 (1999-2000) in 10 Montréal-area high schools. Pre-pandemic...

Background and aims: Variation in the TAS2R38 taste receptor gene alters the ability to taste bitter compounds. We tested whether TAS2R38 variation influences early smoking behaviors in adolescence, a critical period of acquisition when taste may influence the natural course of tobacco use. Design and participants: Observational study (Nicotine...

We examined change in walking, moderate-to-vigorous physical activity (MVPA) and meeting MVPA guidelines from before to during the COVID-19 pandemic, and identified factors associated with newly meeting and no longer meeting MVPA guidelines during the pandemic. Complete data were available for 614 young adults participating in the ongoing Nicotine...

Pleiotropy assessment is critical for the validity of Mendelian randomization (MR) analyses, and its management remains a challenging task for researchers. This review examines how the authors of MR studies address bias due to pleiotropy in practice. We reviewed Pubmed, Medline, Embase and Web of Science for MR studies published before 21 May 2020...

The adoption and maintenance of healthy behaviours including age-appropriate amounts of physical activity, limited sedentary and screen time, and healthy eating are the foundations for youth development and thriving. In reviewing extant evidence, we observe that the COVID-19 pandemic has been associated with marked reductions in physical activity,...

This ecological momentary assessment (EMA) study examined the extent of pain intensity variability among 140 individuals with chronic low back pain and explored predictors of such variability and psychosocial and health care utilization outcomes. Individuals completed momentary pain intensity reports (0–10 numeric rating scale) several times daily...

Background Cannabis users who mix tobacco with cannabis are exposed to nicotine in the tobacco. We identified characteristics of young adult cannabis users who mix and investigated whether mixing frequency is associated with nicotine dependence (ND). Methods Data were collected in self-report questionnaires in 2017-20 from 788 young adults (44% ma...

Background In children, the mechanisms implicated in deterioration of glucose homeostasis vs. reversion to normal glucose tolerance (NGT) remain uncertain. Objective Describe the natural history of dysglycemia from childhood to late adolescence and to identify its early determinants. Methods We used baseline (8-10 yrs, n=630), 1st follow-up (10-1...

We developed and validated an 8-item prognostic tool to identify youth at risk of initiating frequent (i.e., at least weekly) cannabis use in the next year. The tool, which aims to identify youth who would benefit most from clinician intervention, can be completed by the patient or clinician using a computer or smart phone application prior to or d...

Frailty is often described as being an increased vulnerability to the effects of stressors. There is little research investing how frailty may act as either a mediator or participate in interactions in the associations between risk factors and chronic disease. We will present novel analyses of the Canadian Longitudinal Study on Aging, focusing on t...

Introduction: Adequate glycemic control can prevent or delay complications of diabetes. Little is known about the role of glycemic control trajectories on early markers of CVD in youth. Hypothesis: Poor glycemic control trajectory will be associated with increased vascular ageing and altered myocardial structure. Methods: Cross-sectional study of 1...

Background: Modifiable determinants of cardiovascular disease (CVD) remain largely understudied in pediatric type 1 diabetes (T1D). We estimated associations of physical activity and sedentary behavior with markers of CVD in adolescents and tested whether associations differed based on T1D status. Methods: Cross-sectional study of 100 adolescents...

The strong correlation between adiposity and blood pressure (BP) might be explained in part by shared genetic risk factors. A recent study identified three nucleotide variants [rs16933812 (PAX5), rs7638110 (MRPS22), and rs9930333 (FTO)] associated with both body mass index (BMI) and systolic blood pressure (SBP) in adolescents age 12–18years. We at...

Background Frequent injecting increases hepatitis C (HCV) acquisition risk among people who inject drugs (PWID). However, few studies have examined how temporal fluctuations in injecting frequency may effect HCV infection risk. Thus, this study examined HCV incidence according to injecting frequency trajectories followed by PWID over one year in Mo...

Introduction Most studies modeling adolescent cigarette smoking trajectories use age as the time axis, possibly obscuring depiction of the natural course of cigarette smoking. We used a simulated example and real data to contrast smoking trajectories obtained from models that used time since smoking onset or calendar time (age) as the time axis. M...

Background Little is known about how socioeconomic circumstances relate to injection frequencies among people who inject drugs (PWID) with diverse trajectories of injection. We aimed to characterize trajectories of injection drug use in a community-based sample of PWID over 7.5 years and to investigate the extent to which two modifiable factors ref...

Background Knee disorders are highly prevalent and may be a disabling condition. An accurate diagnosis is necessary to guide toward a rapid and efficient management of knee disorders. However, the ability to make a valid diagnosis is often complex for clinicians and evidence is mainly focused on clinician cognitive biases or errors produced during...

Objective: Little is known about changes in alcohol and cannabis co-use over time in adolescents and young adults. We sought to describe the natural course of alcohol and cannabis co-use from age 12 to 17 and 20 to 31 and to describe frequent (i.e., ≥ once/month) binge drinking (i.e., ≥ 5 drinks/occasion) and cannabis use from age 20 to 31. Metho...

Objective Body mass index (BMI) is used to identify trajectories of adiposity in youth, but it does not distinguish fat- from fat-free-mass. There are other inexpensive measures of adiposity which might better capture fat-mass in youth The objective of this study is to examine differences between sex-specific trajectories of BMI and other adiposity...

Background Psychological distress is common among people who inject drugs (PWID) and may be associated with HCV-related risk behaviours. Previous studies have documented increased vulnerability to both psychological distress and HCV infection among female relative to male PWID. It is, however, unclear whether behavioural responses to distress diffe...

Background and Objective: Causal inference methods were developed to emulate repeated randomized trials in observational studies, notably by controlling for time-varying confounders. Using these methods, we examined the complex relationship between physical activity, sedentary behaviors and T2DM accounting for interrelations between time-varying li...

Introduction An association between socioeconomic status (SES) and smoke-free private spaces among smokers could be due to heavier smoking among low SES smokers. We assessed whether quantity smoked or SES are independently associated with smoke-free homes or cars in daily smokers. Method Data were drawn from a cross-sectional telephone survey (201...

Purpose Describing patterns of use, including changes in dose and interruptions is challenging. Group-based trajectory modelling (GBTM) can be used to identify individuals with similar dose patterns. We provide an intuitive graphical representation of dose patterns in groups identified using GBTM. We illustrate our approach using two drugs with dif...

Background : The few observational studies that investigated the long-term effects of interferon-beta and glatiramer acetate were usually focused on progression to irreversible disability and other outcomes such as number of relapses and transition to secondary-progressive multiple sclerosis (SPMS) have been rarely studied. The objective of this pa...

Availability of health-promoting interventions (HPIs) may vary across schools serving students with different socioeconomic backgrounds. Our objectives were to describe social inequalities across elementary schools in: (i) level of importance that school principals attribute to 13 common health-related issues among students in their school; (ii) av...

Introduction We examined the mediating role of friends smoking in the association between depressive symptoms and daily/weekly cigarette smoking from adolescence into adulthood. Methods Data were drawn from the Nicotine Dependence In Teens study (NDIT, Canada) and the Avon Longitudinal Study of Parents and Children (ALSPAC, UK) studies. Three age...

Objective: To evaluate the diagnostic performance of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for grading hepatic inflammation. Methods: In this retrospective cross-sectional dual-center study, 91 patients with chronic liver disease were recruited between September 2014 and September 2018. Patients underwent 3.0-T MRI...

Objective Weight loss attempts occur as early as childhood. The impacts of weight loss attempts and weight‐related stress on the occurrence of obesity during childhood remain unknown. We aimed to: (a) assess the prevalence of self‐reported weight loss attempts and weight‐related stress in 8–10 year‐old children and (b) determine associations with a...

Adolescents often report low moderate-to-vigorous physical activity (MVPA) and high screen time. We modeled sex-specific MVPA and screen time trajectories during adolescence and identified contemporaneous patterns of evolution. Data were drawn from 2 longitudinal investigations. The Nicotine Dependence in Teens (NDIT) study included 1294 adolescent...

Purpose We estimated cross-sectional and longitudinal associations between depression symptoms and night eating in young adults. Methods Data were drawn from a longitudinal investigation of students age 12–13 years at inception in 1999–2000, in Montreal, Canada. Depression symptoms were measured with the Depressive Symptoms Scale (DSS) 20 times fr...

Background The Tika Vaani intervention, an initiative to improve basic health knowledge and empower beneficiaries to improve vaccination uptake and child health for underserved rural populations in India, was assessed in a pilot cluster randomized trial. The intervention was delivered through two strategies: mHealth (using mobile phones to send vac...

Background: Clinical studies suggest that disease course of multiple sclerosis (MS) differs according to age of onset. However, most of these studies were cross-sectional and had modest sample sizes. Population-based administrative data provide an alternative long-term perspective on disease progression and further document the association between...

Objectives: We compared discrete time measures with trajectories of adolescent drinking frequency as predictors of sustained binge drinking in young adulthood. Design: Prospective longitudinal study. Setting: 10 high schools in Montréal, Canada. Participants: 1293 high-school students followed from mean (SD) age 12 (0.6) to 24 (0.7) years....

Trajectory analyses differentiate subgroups of smokers based on early patterns of cigarette use, but no study has summarized this literature. We systematically reviewed the literature on adolescent cigarette smoking trajectories to document the number and shapes of trajectories identified, assess if certain study characteristics influence the numbe...

Objective To describe the natural course of cigarette smoking and nicotine dependence (ND) over 1-year in daily smokers ages 15 to 17 living in different social contexts. Method Cigarette smoking and ND indicators were measured at baseline and 3- and 12-months thereafter among 95 daily smokers with a total of 123 observations from the Nicotine Dep...

Background: Data are lacking on type of e-liquid vaped among e-cigarette users. Further, few studies assess all sources of nicotine used by e-cigarette users to assess whether poly-nicotine use relates to nicotine dependence (ND). The objectives were to describe young adult e-cigarette users by: (i) type of e-liquid vaped; (ii) poly-nicotine use;...

BACKGROUND In resource-poor settings, lack of awareness and low demand for services constitute important barriers to expanding coverage of effective interventions. In India, childhood immunisation is a priority health strategy with suboptimal uptake. OBJECTIVE To assess study feasibility and key implementation outcomes for the Tika Vaani model, a...

Background: In resource-poor settings, lack of awareness and low demand for services constitute important barriers to expanding the coverage of effective interventions. In India, childhood immunization is a priority health strategy with suboptimal uptake. Objective: To assess study feasibility and key implementation outcomes for the Tika Vaani m...

Background: MR elastography is a noninvasive technique that provides high diagnostic accuracy for the staging of liver fibrosis; however, it requires external hardware and mainly assesses the right lobe. Purpose: To evaluate the diagnostic performance of MRI cine-tagging for staging fibrosis in the left liver lobe, using biopsy as the reference...

Objectives We aimed to develop and internally validate a measure of multimorbidity burden using data from the Canadian Longitudinal Study on Aging (CLSA). Design Data from 40 264 CLSA participants (52% men) aged 45–85 years (a mean of 63 years) were analysed. We used logistic regression models to predict overnight hospitalisation in the last 12 mo...

Background Whether polytobacco use or nicotine dependence (ND) change when cigarette smoking status changes in young adults is an understudied issue. Our objective was to describe use of other tobacco products (OTPs) and ND according to change in cigarette smoking status over four years in young adults. Methods We drew data from a longitudinal stu...

Background: Physical activity (PA) can promote mental health, but the mechanisms underpinning this association are not well-established. This study examined if perceptions of three basic psychological needs (autonomy, competence, relatedness) and moderate-to-vigorous physical activity (MVPA) mediate the association between number of years participa...

Introduction: Few interventions target adolescent cigarette smokers to prevent escalation in cigarette use or promote cessation, in part because little is known about co-developing smoking and nicotine dependence (ND). Our objectives were to: (i) estimate developmental trajectories of ND/cravings, withdrawal symptoms, the mFTQ and ICD-10 tobacco d...

Despite limited evidence on the association between physical activity (PA) and blood pressure (BP) in youth, experts recommend that adolescents engage regularly in moderate‐to‐vigorous PA. We examined the relationships between PA intensity and frequency and the likelihood of having high BP in a population‐based cohort of adolescents from Montréal,...

Abstract Youth mental health is a major public health concern. This study assesses whether baseline and short-term changes in mental health predict anxiety and depressive symptoms in college students. Not flourishing mental health at baseline was a risk factor for high levels of anxiety and depressive symptoms. Compared to participants with stable...

Background: The relationship between housing stability and drug injecting is complex, as both outcomes fluctuate over time. The objectives were to identify short-term trajectories of housing stability and injecting frequency among people who inject drugs (PWID) and examine how patterns of injecting frequency relate to those of housing stability....

The CANJEM job-exposure matrix compiles expert evaluations of 31 673 jobs from four population-based case-control studies conducted in Montreal. For each job, experts had derived indices of intensity, frequency, and probability of exposure to 258 agents. CANJEM summarizes the exposures assigned to jobs into cells defined by occupation/industry, age...