My overarching interests are in developmental psychopathology and behavior genetics. In my lab we work at the intersection of psychology, statistics, genetics, and biology to understand the classification, causes, development, and biological underpinnings of psychopathology and relevant personality and neurocognitive traits across the lifespan.
Although we study psychopathology broadly, we also have a specific focus on understanding the causes, classification, and development of childhood externalizing disorders (i.e., ADHD, ODD, and Conduct Disorder [CD]) and behavior problems (e.g., aggression, psychopathic traits), as well as related personality / temperament traits (e.g., callous-unemotionality, negative affect), social cognitive mechanisms (e.g., perception of others’ intention cues), and neurocognitive functions. A major focus of my research centers on disentangling and characterizing the genetic and environmental influences that underlie these traits and disorders, as well as understanding how such factors combine to induce risk for psychopathology. These themes and representative projects are described below.
The Structure and Classification of Psychopathology
It has been known for some time that different psychiatric disorders overlap, a phenomenon termed comorbidity. Although documented in a multitude of studies over many years, what this widespread comorbidity tells us about the structure and classification of psychopathology is not fully clear. Several approaches have been utilized in an effort to deal with comorbidity, including various transdiagnostic and transdimensional approaches. In my lab we actively pursue several hierarchical dimensional approaches to better understand the structure and classification of psychopathology, using large publicly available datasets, as well as data we’ve collected from clinically-referred and population-representative twin-sibling samples.
Quantitative Genetics
We use developmental behavior genetic methods (primarily twin study designs) in which the genetic and environmental influences that underlie disorders and traits can be disentangled and their magnitude can be quantified. We also use these methods to gain a better understanding of comorbidity, in particular the extent to which shared genetic and environmental influences account for the overlap within and among childhood externalizing and internalizing disorders, and the covariation of these disorders with personality traits and social-cognitive and neuro-cognitive functions. In addition, we’ve examined specific environmental influences at a number of different levels (e.g., pre- and peri-natal influences, parenting behavior, family and neighborhood sociodemographic characteristics) and their associations with externalizing psychopathology in quantitative genetic models.
Molecular Genetics
Increasingly we use molecular genetic methods, particularly genome-wide association studies (GWAS), to search for specific genes and biological pathways that underlie these disorders and traits. We have been involved in large-scale GWAS of ADHD, ODD, Conduct Disorder, Bipolar Disorder, antisocial behavior, and the Externalizing spectrum. We are particularly interested in gene-based and pathway-based association tests, genetic correlations among disorders and relevant traits, understanding the biological meaning of associated genes, and uses of polygenic risk scores.
Within the context of quantitative and molecular genetic designs, we also are interested in examining neurocognitive endophenotypes (e.g., lab measures of inattention and impulsivity) and social cognitive mechanisms (e.g., hostile perceptual biases, and deficits and biases in the processing of facial emotions) that may underlie externalizing disorders and other forms of psychopathology, and the development of aggression.
Statistical Methods
We use a variety of sophisticated statistical methods (e.g., Confirmatory and Exploratory Factor Analyses [CFA and EFA], Item Response Theory [IRT]) to test alternative models for the hierarchical dimensional structure of psychopathology in general and externalizing in particular. In addition, we use meta-analytic methods and multivariate quantitative genetic analyses in our research. I’ve also co-authored or edited several pieces focusing explicitly on statistical and methodological issues in the replication and reproducibility of research findings.
Diversity and Inclusiveness
We welcome lab members from diverse backgrounds. In an effort to reduce mental health disparities, we are also actively extending our studies and research findings in the above domains to examine sex differences and similarities and differences in underrepresented individuals, such as individuals from non-European backgrounds. Thus, an interest in and commitment to diversity and inclusiveness is increasingly important to the work in my lab.
Waldman Lab Representative Research Topics
Testing alternative models for the structure of psychopathology broadly and for externalizing psychopathology in particular
Investigating similarities and differences in the structure of psychopathology across ethnicity and sex.