One of the most complex human behaviours that defies singular explanatory models is suicidal behaviour, especially in the youth. A promising approach to make progress with this conundrum is to parse distinct subtypes of this behaviour. Utilizing 1,624 children with suicidal thoughts and behaviors (STBs) and 3,224 healthy controls from the ABCD Study, we clustered children with STB based on thirty-four cognitive and psychopathological measures which capture suicide-related risk-moderating traits. Environmental and genetic risk factors, as well as neuroanatomical characteristics of each subtype, were then compared with controls. We identified five distinct STB subtypes, each revealing unique neuroanatomy, environmental/genetic risks, and persistence patterns. Subtype 1 (Depressive, 9.6%) exhibited the most severe depressive symptoms. Subtype 2 (Externalizing, 20.1%) displayed anatomical and functional alterations in frontoparietal network and increased genetic risk for ADHD. Subtype 3 (Cognitive Deficit, 20.4%) demonstrated lower cognitive performance and widespread white-matter deficits. Subtype 4 (Mild Psychotic, 22.2%) presented higher prodromal psychotic symptoms, often unnoticed by parents. Subtype 5 (High Functioning, 27.6%) showed larger total brain volume, better cognition, and higher socio-economic status, contrasting subtypes 1-4. Only Subtypes 1 and 2 demonstrate persistent STB features at the 2-year follow-up. Our results suggested that youth suicidal behaviour may result from several distinct bio-behavioral pathways that are identifiable through co-occurring psychopathology, and provide insights into the underlying neural mechanisms and corresponding intervention strategies.

LP reports personal fees for serving as chief editor from the Canadian Medical Association Journals, speaker/consultant fee from Janssen Canada and Otsuka Canada, SPMM Course Limited, UK, Canadian Psychiatric Association; book royalties from Oxford University Press; investigator-initiated educational grants from Janssen Canada, Sunovion and Otsuka Canada outside the submitted work.

LP acknowledges research support from the Canada First Research Excellence Fund, awarded to the Healthy Brains, Healthy Lives initiative at McGill University (through New Investigator Supplement to LP); Monique H. Bourgeois Chair in Developmental Disorders and Graham Boeckh Foundation (Douglas Research Centre, McGill University) and salary award from the Fonds de recherche du Quebec-Sante ́ (FRQS). JZ was supported by Science and Technology Innovation 2030 - Brain Science and Brain-Inspired Intelligence Project (STI2030-Major Projects 2021ZD0200204), Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX01), ZJ Lab, Shanghai Center for Brain Science and Brain-Inspired Technology, NSFC 61973086 and the State Key Laboratory of Neurobiology and Frontiers Center for Brain Science of Ministry of Education, Fudan University. XW was supported by State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University.

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https://abcdstudy.org/

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All data produced are available online at https://abcdstudy.org/