Five scientific projects comprise the TAY Cohort Study
Project 1 : Developmental Trajectories of Psychosis Spectrum Symptoms (PSS) and Functioning in the TAY-CAMH Cohort
This project seeks to advance knowledge of the long term trajectories of Psychosis Spectrum Symptoms (PSS) in youth accessing mental health services, aiming to be able to identify those who may need more support earlier, setting the stage for better early intervention and prevention support. While we want to identify all youth in the community with PSS, the vast majority in the Philadelphia Neurodevelopmental Cohort (PNC) study never presented for psychiatric care. Youth awareness of mental issues or illness is typically low, and engagement is a major challenge. Large-scale screening of psychosis in youth, in schools or in the community, is difficult and costly. The approach we propose selects for youth who have already presented for a first appointment in a tertiary care centre (CAMH), and who likely are currently displaying mental health symptoms. Identification of the trajectory, outcomes, and precursors of PSS, have the potential to positively impact clinical practice.
Project 2 : Trajectories of Cognitive Performance and Educational Attainment in Youth with Mental Health Challenges
Identifying trajectories of cognitive and educational performance in mental health treatment-seeking youth and emerging adults with mental health challenges (study-population) as they relate to risk of psychosis spectrum symptoms over the developmental course will:
assist efforts to better identify those most at risk and;
target early intervention and health promotion interventions.
The knowledge gained in this study may contribute to increased understanding of the mechanisms of psychosis development and their early identification. Further, the findings will expand upon prior studies by linking neurocognitive outcomes with real-world outcomes (e.g., educational performance), mental health outcomes (e.g., psychosis and mood symptoms), and other social or biological characteristics. The results may have implications for prevention and intervention efforts, as the transition from late adolescence to emerging adulthood may represent a key developmental target for interventions aimed at lessening the social, emotional, and educational impacts of mental health challenges.
Project 3 : Brain Circuit and Molecular Profile Trajectories in the TAY-CAMH Cohort
Project 3 will explore changes in brain circuitry and molecular profile over time in youth experiencing mental health challenges. Neurodevelopmental disorder and related mental health challenges share similar pathophysiology, but there is also significant neurobiological heterogeneity within each disorder. With regards to psychosis, there is considerable heterogeneity when comparing youth with an ASD, schizophrenia, or bipolar disorder. The cortico-striato-thalamo-cortical circuit is consistently implicated among these disorders, at both the structural and functional levels. The corticolimbic circuit and parasympathetic dysregulation that are affected by adverse experiences are also of interest. Many of the same genes and molecular pathways have been found to be implicated across these disorders, and disorders with psychosis. Neuroimaging techniques will be used for MRI-based measures of brain structure and function. This project will bring together multiple levels of phenotypic analysis that might collectively (directly or indirectly) measure synaptic density and its evolution through adolescence and early adulthood, as well as neuroimmune/inflammatory states, and determine trajectories of brain and molecular profile development over time. We will also be positioned to determine whether these biological trajectories, independent of diagnosis, correspond to different cognitive, functioning, or psychosis symptom profiles.
Project 4 : Service Use Patterns and Health Care Costs Among the TAY-CAMH Cohort
Prior service use data of people who develop a first episode of psychosis, showed that approximately 75% utilized mental health services for other reasons in the three years prior to that presentation for psychosis. Project 4 will use a resource unique to Ontario to capture service use patterns and health care costs in our cohort. Young people participating in the study will have their study data linked to health and other administrative data held at the Institute for Clinical Evaluative Sciences (ICES), if they provide consent for data linkage. ICES holds data on all publicly insured hospital and physician services in Ontario (including outpatient physician visits, emergency department visits, and hospital admissions) and links this data with information on place of residence, neighbourhood income, and immigration status. This allows for the examination of participants’ health service use, both retrospectively and prospectively, including beyond the timeline of primary data collection. Linkage of health administrative data with the extensive sources of other data collected on this cohort allows for the opportunity to explore the manner in which young people are at a higher likelihood of developing psychosis and their families are both connecting with and experiencing higher level systems (health services as well as immigration, social services, financial assistance) and geographic considerations.
Project 5 : Trajectories of Person-Level Networks in the TAY-CAMH Cohort: Data Synthesis
This project will combine data across different platforms to build a comprehensive picture of the whole individual, from genes, to brain, to behaviour, to community. The project serves as a crucial component of the entire study, linking the analyses of Projects 1-4. We will aim to identify the key features highlighted by each project as important for the outcome of psychosis and psychosis symptoms, into those that are independently or interactively important when considered as a whole. Facilitated by machine learning and regression methods, a key goal of this part of the project is to distill the most predictive factors into those most easily assessed in new patients. Finally, a vital step in the discovery of clinical and biological subgroups of participants is testing and calibration in an independent cohort. Both the Adolescent Brain Cognitive Development (ABCD) and Healthy Brain Network (HBN) studies provide such an opportunity in relation to our own dataset, leveraging those aspects of design and population composition that are similar.