Gary Yu


Gary Yu headshot

Gary Yu

Associate Research Scientist
Adjunct Associate Professor

1 212 998 5486

433 First Avenue
Room 745G
New York, NY 10010
United States

Gary Yu's additional information

Gary Yu, PhD, is an associate research scientist and adjunct associate professor at NYU Rory Meyers College of Nursing. He has conducted statistical analyses of data on multiple NIH-funded research projects. 

His dissertation focused on creating a new statistical technique for clustering individuals based on their patterns of responses (e.g., on a questionnaire of drug items). He extended the finite mixture model to allow for the number of repeated measures to be incorporated and contribute to the clustering of individuals. The dimension of the repeated measures can be summarized into a count of responses and can be assumed to follow a truncated Poisson distribution. This information can be included in what is called a dimension informative finite mixture model (DIMM) [NIH/NHLBI R01HL111195]. This model was originally developed and applied to continuous physical activity data, and it has been applied to binary drug items among men who have sex with men (MSM) in the United States and among male sex workers (MSW) in Vietnam.

Yu earned his PhD in biostatistics from Columbia University, MPH in epidemiology from Boston University, and BS in Bioengineering from the University of California, Berkeley.

PhD, Biostatistics - Columbia University (2014)
MPH, Epidemiology - Boston University (2006)
BS, Bioengineering - University of California, Berkeley (2004)

Substance use

Faculty Honors Awards

Bernard Challenor Spirit Prize, Mailman School of Public Health, Columbia University (2014)


Associations of Insomnia Symptoms With Cognition in Persons With Heart Failure

Gharzeddine, R., Yu, G., McCarthy, M. M., & Dickson, V. V. (2021). Western Journal of Nursing Research. 10.1177/0193945920988840
Although cognitive impairment is common among persons with heart failure and negatively impacts self-care, hospitalization, and mortality, the associations between cognitive impairment and insomnia symptoms are not clearly understood. The purpose of this study was to explore these associations and examine if they are maintained after adjusting for relevant sociodemographic, clinical, and lifestyle factors. Guided by the Neurocognitive model of insomnia and sleep and the self-care conceptual model, a cross-sectional data analysis using parametric testing was conducted on the Health and Retirement Study wave 2016. Difficulty initiating sleep and early morning awakening, but not difficulty maintaining sleep were significantly associated with poorer cognitive performance in the bivariate and multivariate analysis. Our results are suggestive of different phenotypes of insomnia symptoms that may have different associations with cognition in persons with heart failure. Further research using objective measurements of insomnia symptoms and detailed neuropsychiatric testing of cognition is needed to confirm this conclusion.

Characterizing Glycemic Control and Sleep in Adults with Long-Standing Type 1 Diabetes and Hypoglycemia Unawareness Initiating Hybrid Closed Loop Insulin Delivery

Malone, S. K., Peleckis, A. J., Grunin, L., Yu, G., Jang, S., Weimer, J., Lee, I., Rickels, M. R., & Goel, N. (2021). Journal of Diabetes Research, 2021. 10.1155/2021/6611064
Nocturnal hypoglycemia is life threatening for individuals with type 1 diabetes (T1D) due to loss of hypoglycemia symptom recognition (hypoglycemia unawareness) and impaired glucose counter regulation. These individuals also show disturbed sleep, which may result from glycemic dysregulation. Whether use of a hybrid closed loop (HCL) insulin delivery system with integrated continuous glucose monitoring (CGM) designed for improving glycemic control, relates to better sleep across time in this population remains unknown. The purpose of this study was to describe long-term changes in glycemic control and objective sleep after initiating hybrid closed loop (HCL) insulin delivery in adults with type 1 diabetes and hypoglycemia unawareness. To accomplish this, six adults (median age=58 y) participated in an 18-month ongoing trial assessing HCL effectiveness. Glycemic control and sleep were measured using continuous glucose monitoring and wrist accelerometers every 3 months. Paired sample t-tests and Cohen's d effect sizes modeled glycemic and sleep changes and the magnitude of these changes from baseline to 9 months. Reduced hypoglycemia (d=0.47-0.79), reduced basal insulin requirements (d=0.48), and a smaller glucose coefficient of variation (d=0.47) occurred with medium-large effect sizes from baseline to 9 months. Hypoglycemia awareness improved from baseline to 6 months with medium-large effect sizes (Clarke score (d=0.60), lability index (d=0.50), HYPO score (d=1.06)). Shorter sleep onset latency (d=1.53; p<0.01), shorter sleep duration (d=0.79), fewer total activity counts (d=1.32), shorter average awakening length (d=0.46), and delays in sleep onset (d=1.06) and sleep midpoint (d=0.72) occurred with medium-large effect sizes from baseline to 9 months. HCL led to clinically significant reductions in hypoglycemia and improved hypoglycemia awareness. Sleep showed a delayed onset, reduced awakening length and onset latency, and maintenance of high sleep efficiency after initiating HCL. Our findings add to the limited evidence on the relationships between diabetes therapeutic technologies and sleep health. This trial is registered with (NCT03215914).

Co-Occurrence of Symptoms and Gut Microbiota Composition Before Neoadjuvant Chemotherapy and Radiation Therapy for Rectal Cancer: A Proof of Concept

González-Mercado, V. J., Lim, J., Yu, G., Penedo, F., Pedro, E., Bernabe, R., Tirado-Gómez, M., & Aouizerat, B. (2021). Biological Research for Nursing. 10.1177/1099800421991656
Purpose: To examine a) whether there are significant differences in gut microbial diversity and in the abundance of gut microbial taxa; and b) differences in predicted functional pathways of the gut microbiome between those participants with high co-occurring symptoms and those with low co-occurring symptoms, prior to neoadjuvant chemotherapy and radiation therapy (CRT) for rectal cancer. Methods: Rectal cancer patients (n = 41) provided stool samples for 16 S rRNA gene sequencing and symptom ratings for fatigue, sleep disturbance, and depressive symptoms prior to CRT. Descriptive statistics were computed for symptoms. Gut microbiome data were analyzed using QIIME2, LEfSe, and the R statistical package. Results: Participants with high co-occurring symptoms (n = 19) had significantly higher bacterial abundances of Ezakiella, Clostridium sensu stricto, Porphyromonas, Barnesiella, Coriobacteriales Incertae Sedis, Synergistiaceae, Echerichia-Shigella, and Turicibacter compared to those with low co-occurring symptoms before CRT (n = 22). Biosynthesis pathways for lipopolysaccharide, L-tryptophan, and colanic acid building blocks were enriched in participants with high co-occurring symptoms. Participants with low co-occurring symptoms showed enriched abundances of Enterococcus and Lachnospiraceae, as well as pathways for β-D-glucoronosides, hexuronide/hexuronate, and nicotinate degradation, methanogenesis, and L-lysine biosynthesis. Conclusion: A number of bacterial taxa and predicted functional pathways were differentially abundant in patients with high co-occurring symptoms compared to those with low co-occurring symptoms before CRT for rectal cancer. Detailed examination of bacterial taxa and pathways mediating co-occurring symptoms is warranted.

Comparison of social cognition using an adapted Chinese version of the Reading the Mind in the Eyes Test in drug-naive and regularly medicated individuals with chronic schizophrenia and healthy controls in rural China

Deng, F., Phillips, M. R., Cai, B., Yu, G., Qian, M., Grivel, M. M., Chen, H., Ouyang, X., Xue, F., Zhao, M., Kegeles, L. S., Susser, E. S., Keshavan, M. S., Stone, W. S., & Yang, L. H. (2021). Psychological Medicine. 10.1017/S003329172100043X
Background Social cognition has not previously been assessed in treatment-naive patients with chronic schizophrenia, in patients over 60 years of age, or in patients with less than 5 years of schooling. Methods We revised a commonly used measure of social cognition, the Reading the Mind in the Eyes Test (RMET), by expanding the instructions, using both self-completion and interviewer-completion versions (for illiterate respondents), and classifying each test administration as 'successfully completed' or 'incomplete'. The revised instrument (RMET-CV-R) was administered to 233 treatment-naive patients with chronic schizophrenia (UT), 154 treated controls with chronic schizophrenia (TC), and 259 healthy controls (HC) from rural communities in China. Results In bivariate and multivariate analyses, successful completion rates and RMET-CV-R scores (percent correct judgments about emotion exhibited in 70 presented slides) were highest in HC, intermediate in TC, and lowest in UT (adjusted completion rates, 97.0, 72.4, and 49.9%, respectively; adjusted RMET-CV-R scores, 45.4, 38.5, and 34.6%, respectively; all p < 0.02). Stratified analyses by the method of administration (self-completed v. interviewer-completed) and by education and age ('educated-younger' v. 'undereducated-older') show the same relationship between groups (i.e. NC>TC>UT), though not all differences remain statistically significant. Conclusions We find poorer social cognition in treatment-naive than in treated patients with chronic schizophrenia. The discriminant validity of RMET-CV-R in undereducated, older patients demonstrates the feasibility of administering revised versions of RMET to patients who may otherwise be considered ineligible due to education or age by changing the method of test administration and carefully assessing respondents' ability to complete the task successfully.

Model-Based Patterns of Lymphedema Symptomatology: Phenotypic and Biomarker Characterization

Fu, M. R., Aouizerat, B. E., Yu, G., Conley, Y., Axelrod, D., Guth, A. A., Gagner, J. P., Qiu, J. M., & Zagzag, D. (2021). Current Breast Cancer Reports, 13(1). 10.1007/s12609-020-00397-6
Purpose of the Study: More than 50% of breast cancer survivors without a diagnosis of lymphedema suffer daily from numerous and co-occurring lymphedema symptoms. This study aimed to identify lymphedema symptom patterns and the association of such patterns with phenotypic characteristics and biomarkers using latent class analysis (LCA). A prospective, descriptive, and repeated-measure design was used to enroll 140 women and collect data. Recent Findings: LCA identified three distinct lymphedema symptom classes at 8 weeks and 12 months post-surgery: low, moderate, and severe symptom classes and associated phenotypic characteristics. Participants were more likely to be in the severe symptom classes at 12 months post-surgery if they had lower education level, cording, an axillary syndrome at 8 weeks post-surgery, neoadjuvant chemotherapy, and radiation. Summary: Pre-surgery level of IL1-a, IL-6, IL-8, and VEGF was associated with the severe symptom class at 8 weeks post-surgery, suggesting that such biomarkers may be used to predict risk for lymphedema symptoms.

An Adapted Conceptual Model Integrating Palliative Care in Serious Illness and Multiple Chronic Conditions

Murali, K. P., Merriman, J. D., Yu, G., Vorderstrasse, A., Kelley, A., & Brody, A. A. (2020). American Journal of Hospice and Palliative Medicine, 37(12), 1086-1095. 10.1177/1049909120928353
Objective: Seriously ill adults with multiple chronic conditions (MCC) who receive palliative care may benefit from improved symptom burden, health care utilization and cost, caregiver stress, and quality of life. To guide research involving serious illness and MCC, palliative care can be integrated into a conceptual model to develop future research studies to improve care strategies and outcomes in this population. Methods: The adapted conceptual model was developed based on a thorough review of the literature, in which current evidence and conceptual models related to serious illness, MCC, and palliative care were appraised. Factors contributing to patients’ needs, services received, and service-related variables were identified. Relevant patient outcomes and evidence gaps are also highlighted. Results: Fifty-eight articles were synthesized to inform the development of an adapted conceptual model including serious illness, MCC, and palliative care. Concepts were organized into 4 main conceptual groups, including Factors Affecting Needs (sociodemographic and social determinants of health), Factors Affecting Services Received (health system; research, evidence base, dissemination, and health policy; community resources), Service-Related Variables (patient visits, service mix, quality of care, patient information, experience), and Outcomes (symptom burden, quality of life, function, advance care planning, goal-concordant care, utilization, cost, death, site of death, satisfaction). Discussion: The adapted conceptual model integrates palliative care with serious illness and multiple chronic conditions. The model is intended to guide the development of research studies involving seriously ill adults with MCC and aid researchers in addressing relevant evidence gaps.

Association between the Duration of Untreated Psychosis and Selective Cognitive Performance in Community-Dwelling Individuals with Chronic Untreated Schizophrenia in Rural China

Phillips, M. R., Stone, W. S., Cai, B., Liu, X., Grivel, M. M., Yu, G., Xu, Y., Ouyang, X., Chen, H., Deng, F., Xue, F., Li, H., Lieberman, J. A., Keshavan, M. S., Susser, E. S., & Yang, L. H. (2020). JAMA Psychiatry, 77(11), 1116-1126. 10.1001/jamapsychiatry.2020.1619
Importance: Cognitive deficits constitute core features of schizophrenia, but the trajectories of cognitive difficulties in chronic untreated schizophrenia remain unclear. Objective: To assess the association of neuropsychological deficits with duration of untreated psychosis in individuals with chronic untreated schizophrenia. Design, Setting, and Participants: Community-dwelling individuals with chronic untreated schizophrenia (untreated patient group) and individuals without mental illness (control group) were recruited from predominantly rural communities in Ningxia, China between June 20, 2016, and August 6, 2019, and administered the Structured Clinical Interview for DSM-IV, the Mini-Mental State Examination, an 8-test version of the MATRICS Consensus Cognition Battery adapted for use in individuals with low levels of education, and a measure of social cognition. Main Outcomes and Measures: Comparison of cognitive test scores between the two groups and association of cognitive test scores with duration of untreated schizophrenia. Results: The patient group included 197 individuals with chronic untreated schizophrenia (101 men [51.3%]; mean [SD] age, 52.1 [11.8] years; median [interquartile range] years of schooling, 3 [0-6] years; median [interquartile range] years of untreated psychosis, 22.9 [14.9-32.8] years). The control group included 220 individuals (118 men [53.6%]; mean [SD] age, 52.1 [11.2] years; median [interquartile range] years of schooling, 4 [0-6] years). The untreated patient group performed significantly worse than the control group on all cognitive measures (adjusted partial Spearman correlation coefficient [Spearman ρ] ranged from-0.35 for the revised Chinese version of the Reading the Mind in the Eyes Test to-0.60 for the Brief Visuospatial Memory Test-Revised; P <.001 for all comparisons). Longer durations of untreated psychosis were associated with lower performance in 3 MATRICS Consensus Cognition Battery measures assessing different aspects of executive functioning (Brief Visuospatial Memory Test-Revised [ρ =-0.20; P =.04]; Brief Assessment of Cognition in Schizophrenia, Symbol Coding subtest [ρ =-0.35; P <.001]; and Neuropsychological Assessment Battery, Mazes subtest [ρ =-0.24; P =.01]). The median duration of untreated psychosis (22.9 years) was associated with estimated score reductions in the 3 measures of 34% (95% CI, 10%-52%), 43% (95% CI, 28%-55%), and 57% (95% CI, 31%-73%), respectively. Conclusions and Relevance: The findings of this study suggest that long-term untreated schizophrenia was associated with decreases in selective cognitive abilities; both neurodegenerative pathology and neurodevelopmental dysfunction may be factors in cognition in persistent psychosis. Expanding research to include cohorts of patients from underserved rural communities in low- A nd middle-income countries may provide new insights about the etiological factors, disease course, and management of schizophrenia.

Child labor, sex and mental health outcomes amongst adolescent refugees

Meyer, S. R., Yu, G., Rieders, E., & Stark, L. (2020). Journal of Adolescence, 81, 52-60. 10.1016/j.adolescence.2020.04.002
Introduction: Refugee adolescents living in camps and settlements in low and middle-income countries are a vulnerable population who face protection and psychosocial risks. This study explores prevalence of child labor amongst adolescent refugees from South Sudan in two refugee settlements in Uganda, to understand impacts of child labor on mental health outcomes, and examines the influence of sex on these impacts. Methods: Surveys were conducted in Adjumani and Kiryandongo refugee settlements, Uganda, with 470 adolescents between 13 and 17 interviewed between December 2014–February 2015. Univariate finite mixture modeling identified a two-cluster model of child labor. Logistic regression models assessed the association of child labor and mental health. Results: A two-cluster solution for child labor activity was determined among the 332 adolescents who self-reported engaging in any child labor (Significant child labor: n = 174, 37%; moderate child labor cluster: n = 158, 34%; no child labor cluster: n = 138, 29%. Odds of depression amongst adolescents exposed to significant vs. no child labor was 4.15 (95% CI: 2.01–8.56), in a model examining interaction of sex and child labor and controlling for socio-demographic variables. For the anxiety outcome, girls exposed to significant vs. no child labor are less likely to report higher levels of anxiety (OR: 0.29, 95% CI: 0.09–0.90). Conclusions: Adolescents living in refugee settlements in Uganda report high levels of participation in child labor. Protection of adolescents from the risks involved with child labor in refugee contexts is an important and often over-looked area of child protection in humanitarian settings.

Children with Incarcerated Parents and Developmental Trajectories of Internalizing Problems across Adolescence

Kjellstrand, J., Yu, G., Eddy, J. M., & Clark, M. (2020). American Journal of Criminal Justice, 45(1), 48-69. 10.1007/s12103-019-09494-4
Research over the past several decades has documented the effect of parental incarceration on child development. While many findings point to a negative impact of parental incarceration on children, increasingly research demonstrates the heterogeneity of children’s experiences, behavior, and eventual outcomes. Examining this heterogeneity is key to developing effective interventions that enhance protective factors while addressing especially harmful risk factors. In the current study, we used growth mixture modeling to identify distinct trajectories of internalizing problems for youth (N = 655) from 10 to 16 years of age. We then examined the relations of the identified trajectories with parental incarceration, parent-child relationships, stressful life events, and parenting as well as future substance use, criminality, and suicidality (ideation and attempt). Four trajectory classes were identified: Low-Stable, Pre-Adolescent Limited, Moderate-Increasing, and High-Decreasing. Over half of the children who had experienced parental incarceration were best represented by the low risk trajectory. However, children with incarcerated parents were underrepresented in this trajectory and overrepresented in two of the three problematic trajectories. The trajectory classes differed significantly on many of the pre-adolescent measures as well as on adolescent delinquency, substance use, suicide ideation and suicide attempt. The Pre-Adolescent Limited, Moderate-Increasing, and High-Decreasing showed significantly higher levels of early risk factors and problematic outcomes than the Low-Stable trajectory group. Implications are discussed.

Complementary low-level laser therapy for breast cancer-related lymphedema: a pilot, double-blind, randomized, placebo-controlled study

Kilmartin, L., Denham, T., Fu, M. R., Yu, G., Kuo, T. T., Axelrod, D., & Guth, A. A. (2020). Lasers in Medical Science, 35(1), 95-105. 10.1007/s10103-019-02798-1
This pilot, double-blind, randomized, placebo-controlled study is aimed at evaluating the effectiveness of low-level laser therapy (LLLT) as a complementary treatment to complete decongestive therapy (CDT) treating lymphedema among breast cancer patients for 12 months post-intervention. Study population was breast cancer patients who were diagnosed and referred to lymphedema clinic for CDT. Participants (n = 22) were randomized and assigned into either an active laser intervention group or an inactive laser placebo-control group. Active LLLT was administered to participants twice a week at the beginning of each CDT session. Outcome measures included lymphedema symptoms, symptom distress, and limb volume by an infrared perometer. Participants in the active and placebo laser groups were comparable in demographic and clinical predictors of lymphedema. In comparison with the placebo group (83.3%), significantly fewer participants in the active laser group (55.6%) reported more than one lymphedema symptom (p = 0.012) at 12 months post-intervention. Significantly, more patients in the active laser group (44.4%) reported less than two impaired limb mobility symptoms in comparison with the placebo group (33.3%) at 12 months post-intervention (p = 0.017). The active laser group had statistically significant improvements in symptom distress of sadness (p = 0.005) from 73 to 11% and self-perception (p = 0.030) from 36 to 0% over time from baseline to 12-months post-intervention. There was no significant reduction in limb volume. Findings of the trial demonstrated significant benefits of complementary LLLT for relieving symptoms and improvement of emotional distress in breast cancer patients with lymphedema.