Transdiagnostic Trajectories

Transdiagnostic Trajectories Towards Sever Mental Illness

We have made substantial contributions to the idea that individual presentations and experiences are likely to shift diagnostic categories en route to a severe mental illness, and the implications of this for youth mental health services and systems. In psychosis, we mobilized multiple streams of data to challenge the assumption that all individuals with a full-blown first episode of psychosis invariably pass through an earlier stage of milder (sub-threshold) psychotic symptoms. This has now been taken up as a central piece of evidence that service development should be reorganized around variable (rather than solely linear) pathways to severe mental illnesses. We have also demonstrated that this distinction – between whether patients did or did not have early sub-threshold psychotic symptoms – in turn predicts a range of other outcomes, including differences in neurobiology, service engagement, and treatment delays. Overall, it reveals that early-stage features have important and unrecognized prognostic value for endpoints at later stages.

Follow-back studies of trajectories to psychosis: Funded by CIHR and Sick Kids Foundation, we have undertaken unique analyses of data examining a full (catchment-based first episode psychosis sample) and the retrospective trajectories to that outcome.

Key Projects:

Renaud-Charest O, Paquin V, Daneault JG, Malla AK, Joober R, Iyer SN, Lepage M, Shah JL (2025). Subcategories of the Clinical High-Risk State for Psychosis and Their Relationship to a Full First-Episode Psychosis Sample: An Exploratory Analysis of Longitudinal Outcomes. Schizophrenia Bulletin, 1-9.
Paquin V, Malla A, Iyer SN, Lepage M, Joober R, Shah JL (2023). Combinations and temporal associations among precursor symptoms before a first episode of psychosis. Schizophrenia Bulletin, in press.
McIlwaine SV, Mughal S, Ferrari M, Rosengard R, Malla A, Iyer SN, Lepage M, Joober R, Shah JL (2023). Pre-onset subthreshold symptoms are associated with differential treatment delays before a first episode of psychosis: Initial evidence and implications. Schizophrenia Research, in press.
Paquin V, Malla A, Iyer SN, Lepage M, Joober R, Shah JL (2023). Transsyndromic trajectories from pre-onset self-harm and subthreshold psychosis to the first episode of psychosis: A longitudinal study. Journal of Psychopathology and Clinical Science, 132(2), 198–208.
Benrimoh D, Dlugunovych V, Wright AC, Phalen P, Funaro MC, Ferrara M, Powers A, Woods S, Gülöksüz S, Yung AR, Srihari V, Shah J (2023). On the proportion of patients who experience a prodrome prior to psychosis onset: A systematic review and meta-analysis. Molecular Psychiatry, in press.
Shah JL, Paquin V, McIlwaine SV, Malla AK, Joober R, Pruessner M (2023). Examining the psychobiological response to acute social stress across clinical stages and symptom trajectories in the early psychosis continuum. Development and Psychopathology, 1-13.
Paquin V, Cupo L, Malla A, Iyer SN, Joober R, Shah JL (2021). Dynamic association of the first identifiable symptom with rapidity of progression to first episode psychosis. Psychological Medicine, 1-9.