The Canadian Health Survey on Children and Youth (CHSCY) Childhood Experiences Scale includes 10 items assessing youth's self-reported exposure to different forms of maltreatment by their caregivers, including physical, sexual and emotional abuse, neglect, as well as exposure to violence between caregivers. One additional item captures youth's exposure to corporal punishment. Items have been administered in population-based studies that include samples of youth and adults, as well as clinical observational studies and trials. Total scores can range from a minimum of 10 to a maximum of 50, with higher scores indicating more negative experiences.

The Child and Youth Resilience Measure is a screening tool to explore the resources (individual, relational, communal and cultural) available to individuals that may bolster their resilience. Individuals aged 24+ will be asked to complete the Adult Resilience Measure. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

The Columbia Suicide Severity Rating Scale is a validated and widely used rater-administered measure of suicidal ideation and behaviour, and non-suicidal self-injury. It will be administered to all participants. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

The Self-Injurious Thoughts and Behaviours Interview (SITBI) measures self-injurious thoughts and behaviors.

The Canadian Health Survey on Children and Youth (CHSCY) Bullying Scale includes 10 items and is designed to assess youth exposure to bullying in the preceding 12 months. Items capture both the type and frequency of bullying, with types of bullying covered by the measure including verbal, physical, relational, and online forms of bullying. Response options are captured on an ordinal scale encompassing: Never, A few Times a Year, Monthly, Weekly, Daily. Total scores can range from a minimum of 10 to a maximum of 50, with higher scores indicating more experiences with bullying.

The Difficulties in Emotion Regulation Scale Short Form is an 18-item measure used to identify emotional regulation issues. The measure covers 4 dimensions of emotional regulation: awareness and understanding of emotions; acceptance of emotions; the ability to engage in goal-directed behavior and refrain from impulsive behavior when experiencing negative emotions; and access to emotion regulation strategies perceived as effective. Total scores can range from a minimum of 18 to a maximum of 90, with higher scores indicating more difficulties with emotion regulation.

The Eating Disorder Examination Questionnaire (EDE-QS) Short Form is a 12-item, self-report questionnaire capturing eating disorder symptoms. Response options are anchored on a 4-point ordinal response scale that captures symptoms over the preceding 7 days. Total scores can range from a minimum of 0 to a maximum of 36, with higher scores indicating the presence of more eating disorder symptoms.

The General Anxiety Disorder-7 (GAD-7) measures presence and severity of Generalized Anxiety Disorder. Total scores can range from a minimum of 0 to a maximum of 21, with higher scores indicating greater presence and severity of anxiety symptoms.

The General Behaviour Inventory-10 Mania measures the presence and severity of mania. Total scores can range from a minimum of 0 to a maximum of 30, with higher scores indicating greater presence and severity of mania.

A singular question from the Canadian Social Survey - Quality of Life and Energy Consumption Behaviours measure will be administered to determine life satisfaction. Total scores can range from a minimum of 0 to a maximum of 10, with higher scores indicating greater life satisfaction.

The Goal-Based Outcome (GBO) Tool aims to measure the progress and outcomes of an intervention in a simple way. It can be applied in any setting and is currently available in 9 languages. The child GBO tool contains a record sheet whereby up to 3 goals with their descriptions can be written down, followed by a goal rating sheet with descriptions and a scale ranging from 0 (Goals not at all met) to 10 (Goal reached). A goal progress chart at the end can be used to rate the progress of the goal across 12 sessions.

The Internalized Stigma of Mental Illness (ISMI) scale is a questionnaire measuring self-stigma among persons with psychiatric disorders. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

This measure consists of two parts. The first part has six items, and asks questions based on typical weekday activity in the last week. The second part also includes six items and asks questions pertaining to typical weekend activities within the last week. Higher scores equate to more sedentary behaviors in a participant.

The McMaster Family Functioning Scale is a shorter 12-item assessment developed from The McMaster Family Assessment Device, which is a 60-item questionnaire that measures an individual's perceptions of their family. Total scores can range from a minimum of 12 to a maximum of 48, with higher scores indicating more positive perceptions of family.

This inventory records prescribed treatment and medication, adherence and tolerability every 6 months.

The Ohio State University Traumatic Brain Injury Identification Method measures a participant's history of traumatic brain injury. Baseline and follow-up versions will be administered.

The Ontario Child Health Study Emotional Behavioural Scales - Brief (OCHS-EBS-B) is a 25-item measurement tool for participants under the age of 18 that assesses common child/youth mental health disorders within the last 6 months. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

The Patient Global Improvement Scale evaluates all aspects of patients' health and assesses if there has been an improvement or decline in clinical status. Scores range from 0 to 7, with lower scores reflecting more positive symptoms and thus improvement in clinical status.

The Patient Health Questionnaire (PHQ) is a self-administered version of the Primary Care Evaluation of Mental Disorders (PRIME-MD) diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the 9 DSM-IV criteria as 0 (not at all) to 3 (nearly every day).

This assessment is designed to evaluate the overall sleep quality in a clinical population. It is a 19-item self-reported questionnaire assessing seven subcategories; use of sleeping medication, subjective sleep quality, sleep latency, duration, sleep efficiency, disturbances and dysfunction during the daytime. Each subcategory ranges from scores of 0 to 3, with higher scores reflecting poorer sleep patterns.

Blood will be collected by a trained phlebotomist or research nurse with experience working with children and youth. Blood will be collected at baseline, and then annually. A maximum of 40 mL of blood will be collected per participant; however, sites may collect reduced volumes due to site-specific procedures and/or participant limitations. To ensure sufficient sample volumes for clinical and genetic/immune analyses, a minimum collection threshold will be applied to each.

Clinical testing (7-20 mL): Samples will be transferred to clinical labs for CBC, differential white cell count, HbA1C, CRP, glucose, and lipid testing.

Genetic and immune analysis (16-20 mL): Samples will be analyzed for genetic, epigenetic, and immune markers.

Sites will aim to collect the full 20 mL for both clinical and genetic testing whenever possible.

A physical exam will be completed by trained research or clinical staff during the clinic visit. If the participant is unable to attend the clinic visit, research staff will use recent values from their medical record or provide instructions to the participant for measuring their height, weight, waist circumference and neck circumference at home (blood pressure will not be measured at home).

This is a self-administered questionnaire that is designed to assess individuals at risk for developing a psychotic disorder. It contains 12 items that assess positive symptoms on a distress scale ranging from 0 (Definitely disagree) to 6 (Definitely agree).

The Revised Child Anxiety and Depression Scale (RCADS-25) is a self-report questionnaire that assesses symptoms of depression and anxiety in children and adolescents. This assessment captures symptoms related to generalized anxiety disorder (GAD), major depressive disorder (MDD), panic disorder, social phobia, separation anxiety disorder (SAD), and obsessive-compulsive disorder (OCD).

Participants will be asked to provide a saliva sample to be used for genetic and epigenetic analyses. A saliva collection kit, such as that made by Oragene, will be used. Approximately 1.5 mL of saliva is provided when someone 'spits' into the collection tube. Cheek cells in saliva contain the DNA that will ultimately be extracted and processed.

The Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS) uses seven statements about thoughts and feelings to monitor mental wellbeing. The seven statements are positively worded with five response categories from 'none of the time' to 'all of the time'. Children and young people are asked to describe their experiences over the past two weeks.

The Social Communication Questionnaire (40-item parent questionnaire), which is based on the Autism Diagnostic Interview-Revised, will be used to measure current and developmental social communication deficits. This parent-report questionnaire provides information regarding social communication and repetitive behaviours present currently and from early childhood. Total scores can range from a minimum of 0 to a maximum of 39, with higher scores indicating stronger social communication.

The Social Responsiveness Scale measures the severity of autism symptoms in a quantitative manner, both among children affected by symptoms that fall under the spectrum of autism as well as among children in the general population. Caregivers will complete the caregiver report school short form. Total scores can range from a minimum of 16 to a maximum of 64, with higher scores indicating lower social responsiveness.

The Strengths and Weaknesses of Attention-Deficit/Hyperactivity Disorder Symptoms and Normal Behavior scale assesses ADHD symptoms in the clinical and non-clinical population. It includes a set of 18 questions and a child's behavior is scored on a 7-point scale with 4 (average) reflecting a normal behavior for the child's age. The first 9 items are associated with inattentive ADHD and the next 9 items are associated with hyperactive/impulsive ADHD.

The Suicidal Ideation Questionnaire-Junior (SIQ-JR) consists of 15 items and will be completed by all youth in this study. It is designed for students in Grades 7-9. This assessment assists in informing adults/professionals of their levels of distress and suicidal intent without self-injurious behaviour. The overall aim of this measure is to assess suicidal ideation and risk.

The Toronto Obsessive-Compulsive Scale (TOCS) is a 21-item parent or self-report questionnaire that assesses symptoms pertaining to Obsessive-Compulsive traits among children or adolescents. Total scores can range from a minimum of -72 to a maximum of 72, with higher scores indicating the presence of more Obsessive-Compulsive traits.

The Unmet Needs Questionnaire measures the services participants are receiving and whether their needs are being met.

The Youth Life Interference Scale (YLIS) is an 11-item self-report measure assessing the impact of mental health symptoms on day-to-day functioning in the past two weeks. The measure was developed in-house for the TAY study. Its focus lies on functional impairment related to anxiety and depression for youth. Total scores can range from a minimum of 0 to a maximum of 36, with higher scores indicating greater functional impairment.

The Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) is a widely used structured diagnostic interview that will be administered to participants in order to determine the presence of categorical mental health diagnoses. The K-SADS will be used for participants less than 18 years of age.

This is a self-report screening measure for psychosis risk syndromes. It records psychosis-like symptoms that would have occurred over the past month. For each item in the questionnaire that is endorsed, responses range in levels of distress or impairment from a scale of 1 (strongly disagree) to 5 (strongly agree).

The Structured Interview for Prodromal Symptoms Negative/Disorganized Subscales is a diagnostic semi-structured interview used to assess the severity of symptoms and diagnose prodromal syndromes.

The Adolescent Alcohol and Drug Involvement Scale (AADIS) Revised is a self-report measure of adolescent problematic substance abuse, and will be used to quantify frequency of past-year substance use (including cannabis use). This scale also provides a numerical score derived from items related to behaviors associated with problematic use. Total scores can range from a minimum of 0 to a maximum of 84, with higher scores indicating more frequent use of substances.

Participants will be asked to fill in a self-report questionnaire measuring educational attainment which takes about 5 minutes to complete. The revised Educational Attainment Questionnaire will assess level of education, grades and accommodations or other support at school among other education-related items. Participants fill in the Educational Attainment Questionnaire at baseline. The Educational Attainment Questionnaire is composed of several items from the School Mental Health Survey that is part of the Ontario Child Health Study, a longstanding prospective study on the overall health of children in Ontario.

Autism spectrum symptoms will be evaluated using the long form of the Social Responsiveness Scale (SRS-2), which is a validated brief measure of autism traits consisting of 65 items. Caregivers will complete the caregiver report school version. Total scores can range from a minimum of 65 to a maximum of 260, with higher scores indicating the presence of more autism traits.

The Columbia Impairment Scale (CIS) is a 13-item self and caregiver report scale which provides a global measure of impairment in 4 major areas of functioning: interpersonal relations (family and friends), broad psychopathological domains, job or school functioning, and use of leisure time. Total scores can range from a minimum of 0 to a maximum of 52, with higher scores indicating more global impairment.

The Global Functioning: Social and Role Scales assessment measures social and role functioning through a semi-structured interview. Total scores can range from a minimum of 1 to a maximum of 10, with higher scores indicating greater functioning.

The Self-report World Health Organization - Disability Assessment Schedule is a 12-item generic assessment instrument for health and disability. This tool produces standardized disability levels and profiles directly linked at the level of the concepts to the International Classification of Functioning, Disability and Health (ICF), and covers six domains of functioning: cognition, mobility, self-care, getting along, life activities, and participation. Total scores can range from a minimum of 0 to a maximum of 48, with higher scores indicating lower functioning.

Youth will be asked to self-report their mental health and other health and social service utilization using an adapted version of the Health and Social Service Utilization measure that has been previously used with this population, including in the current Longitudinal Youth in Transition Study at the Centre for Addiction and Mental Health (CAMH). Additional items are adapted from the Ontario Student Drug Use and Health Survey.

The Transition Readiness Assessment Questionnaire (TRAQ) will be used to assess the transition readiness of youth between the ages of 15 and 19 from youth to adult mental health services. Total scores can range from a minimum of 20 to a maximum of 100, with higher scores indicating greater transition readiness.

The Internet Addiction Test measures the presence and severity of problematic internet use across six addictive domains: Conflict, Mood Modification, Salience, Tolerance, Relapse, and Withdrawal.

The Parent Child Internet Addiction Test measures the presence and severity of problematic internet use. This test is a 20-item measure asking the parent to indicate the frequency of behaviours in the child on a 6-point scale ranging from 'Does not apply' to 'Always'.

The Leisure Time Questionnaire is used to assess time spent in leisure activities.

Youth participants enrolled in the deep phenotyping cohort will be asked to complete an MRI scan at their participating site for approximately 1 hour. Each scan will consist of high-quality T1-weighted, diffusion MRI (dMRI) and r-fMRI sequences that will be combined into a single neuroimaging output per participant.

The Edinburgh Handedness Inventory (EHI) - Brief is a four-item questionnaire used to assess laterality. Youth are asked to report the dominance of the right or left hand in everyday activities. Scores range from -100 (indicating left preference) to 100 (indicating right preference).

The Snellen Chart is an eye chart commonly used to assess visual acuity using eleven lines of block letters. Participants are asked to stand ten feet from the chart and to read the letters of each row aloud, beginning from the top row.

The Toolbox Dimensional Change Card Sort Task assesses cognitive flexibility. Youth are presented with two stimuli at the bottom of the screen and asked to sort a third stimulus presented in the middle of the screen to match one of the two stimuli at the bottom, by either colour or shape.

The Toolbox Flanker Task assesses attention and inhibitory control. Youth are presented with a target stimulus and two surrounding flanker stimuli, and are asked to indicate which direction the middle stimulus is facing (left or right); surrounding flanker stimuli may be facing in the same direction (congruent trials) or the opposite direction (incongruent trials).

The Toolbox List Sorting Working Memory Test assesses working memory sequencing skills. Youth are presented with animals and foods of assorted sizes both visually and auditorily, and asked to list the items presented from smallest to largest. This test is repeated using items from a single category, and items from two categories; in the latter, youth are requested to list items from one category and then the other.

The Toolbox Oral Reading Recognition Task assesses language exposure and reading skills. Youth are asked to pronounce visually presented letters or words.

The Toolbox Pattern Comparison Processing Speed Test assesses visual processing. Youth are asked to determine whether two visually presented pictures are the same.

The Toolbox Picture Sequence Memory Test assesses episodic memory. Youth are presented with 15 pictures demonstrating events and are asked to model those events as a series of actions using props.

The Toolbox Picture Vocabulary Task assesses language and verbal intellect. Participants are auditorily presented with a word and asked to choose which of four visually presented pictures matches that word.

The Rey Auditory Verbal Learning Test (RAVLT) assesses auditory learning and memory. Youth are asked to listen to and recall a list of 15 unrelated words over five learning trials. They are then presented with and asked to recall as many words from a second, distractor list of 15 words, and recall of the initial list is then assessed.

This subtest of the Wechsler Intelligence Scale for Children assesses nonverbal reasoning, as well as visual intelligence, part-whole spatial reasoning, perceptual organization, attention to visual detail, and sequencing. Youth are presented with an incomplete array of visually presented stimuli, and asked to select one of four alternatives to complete the array. For participants aged 16 years or over, the Wechsler Adult Intelligence Scale-IV (WAIS-IV) version of this task will be administered.

The Little Man Task (LMT) assesses visual-spatial processing, including mental rotation. Youth are asked to indicate which hand a figure is using to hold a briefcase after being presented with the figure in one of four positions.

Delay discounting can be defined as the depreciation of the value of a reward related to the time that it takes to be released. The task is an index of impulsive behaviour. Participants play a game in which they make a choice between an immediate small reward and a delayed larger reward.

The Emotional Stroop Task is a modified version of the traditional Stroop task in which participants are required to name the ink color of words with emotional or neutral valence. This task is commonly used to measure the attentional biases toward emotional stimuli typically observed in humans.

The Penn Emotion Differentiation Task measures the social cognition domain of emotion identification - the ability to decode and correctly identify facial expressions of emotion. Youth are shown 40 faces and must determine whether the emotion expressed is happiness, sadness, anger, fear, or none at all.

The Awareness of Social Inference Test (TASIT) - Short Version measures social cognition using videos of naturalistic everyday conversations in which two actors interact. It has established ecological validity, reliability and construct validity. Alternate forms are available for re-testing.

The Parental Bonding Instrument (PBI) was designed to measure the contribution of parental behavior to the development of appropriate bonds between parents and children. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

The Personality Inventory for DSM-5 Faceted Brief Form (PID-5-FBF) will be used to examine maladaptive personality traits. The PID-5-FBF is a 100-item self-rated personality trait assessment scale for adolescents and adults. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

This is an 8-item questionnaire originally developed for the TAY study.

This measure is a questionnaire measuring physical activities in the last 7 days.

This measure assesses types of pain and frequency, and the impact of pain on 5-point Likert scales. For each pain item the participant needs to indicate if pain can be explained by a physical accident or diagnosed medical condition.

This scale contains five items, with the last two items being different for males and females. It assesses the presence of developmental changes associated with puberty. Total scores can range from a minimum of 5 to a maximum of 20, with higher scores indicating the presence of more developmental changes.

The Social Media Addiction Questionnaire (SMAQ) is comprised of questions adapted from the Ontario Student Drug Use and Health Survey. These questions will be used to collect information on screen time use, problematic social media use and video game use, respectively, as reported by the youth participant. Total scores can range from a minimum of 6 to a maximum of 36, with higher scores indicating more problematic use of social media.

The Acculturation Questionnaire will be used to measure speaking and reading skills in English and language preference. This measure includes multiple subscale scores assessing different domains, with scores interpreted separately by subscale.

The Mexican American Cultural Values Scale (50 items) is used to assess family values of individuals from diverse cultural backgrounds. Total scores can range from a minimum of 50 to a maximum of 250, with higher scores indicating less adherence to the outlined cultural values.

The Multigroup Ethnic Identity-Revised will be used to measure cultural affiliation. This measure contains 6 items that can be rated on a five-point scale from strongly disagree to strongly agree. Total scores can range from a minimum of 6 to a maximum of 24, with higher scores indicating stronger cultural affiliation.

The Vancouver Index of Acculturation - Short will be used to measure acculturation with 20 items that can be rated from disagree to agree on a 9-point scale. Total scores can range from a minimum of 10 to a maximum of 90, with higher scores indicating greater acculturation.

Family and social influences including parental monitoring and interactions with family members will be measured using the Parental Monitoring questionnaire. Total scores can range from a minimum of 5 to a maximum of 25, with higher scores indicating higher parental involvement.

Family and social influences including prosocial behaviors and interactions with family members will be measured using the Prosocial Scale. Total scores can range from a minimum of 0 to a maximum of 10, with higher scores indicating more prosocial behaviors.

Family and social influences including interactions with family members will be measured using the Conflict Behavior Questionnaire. Total scores can range from a minimum of 0 to a maximum of 20, with higher scores indicating the presence of more conflict-related behaviors.

In addition to self-reported gender obtained using the demographic protocol, gender expression will be measured using the Gender Dysphoria Questionnaire for Adolescents and Adults. Total scores can range from a minimum of 27 to a maximum of 135, with higher scores indicating greater satisfaction and less gender-related distress.

In addition to self-reported gender obtained using the demographic protocol, gender identity variability will be measured using the Personal Attributes Questionnaire. Total scores can range from a minimum of 0 to a maximum of 96, with higher scores indicating stronger self-perceptions of gender attributes.

Life events and current life stress will be assessed in all participants below age 18 using The Adverse Life Events Scale. Total scores can range from a minimum of 0 to a maximum of 25, with higher scores indicating more adverse life events and/or related stress.

All participants will be administered the Childhood Trauma Questionnaire - Short Form to identify traumatic childhood conditions. Total scores can range from a minimum of 28 to a maximum of 125, with higher scores indicating greater exposure to traumatic childhood conditions.

Individual resilience in the face of stress will be measured using a brief, two-item version of the Connor-Davidson Resilience Scale. Total scores can range from a minimum of 0 to a maximum of 8, with higher scores indicating higher resilience.

Lifetime discriminatory experiences will be assessed in all participants using a Canadian adaptation of the Everyday Discrimination Scale. Total scores can range from a minimum of 5 to a maximum of 25, with higher scores indicating greater discriminatory experiences.

The Life Events Checklist (LEC) is designed to screen for potentially traumatic experiences that may contribute to psychological distress. Participants aged 18 and above will be administered the Life Events Checklist.

All participants' school environments will be characterized using the Inventory for School Risk and Protective Factors measure from the ABCD study. Total scores can range from a minimum of 6 to a maximum of 24, with higher scores indicating greater protective factors.

In the proximal social environment, neighbourhood safety will be measured using a three-item Neighbourhood Safety and Crime Scale. Total scores can range from a minimum of 3 to a maximum of 15, with higher scores indicating lower perceived neighbourhood safety.

3-digit postal codes of participants (collected as part of routine demographic data) will be used to obtain census-based neighbourhood-level marginalization data; this will allow each participant's neighbourhood to be characterized by the level of social and economic marginalization as well as ethnic concentration. At the time of cohort entry, the first 3 digits of each participant's postal code are collected based on the participant's residential address. Any change in a participant's residential address will also be recorded during assessment periods during the study to account for changes in exposure to socio-environmental factors.

Caregivers will complete the Parent General Behaviour Inventory-10 Mania, which measures the presence and severity of mania. Total scores can range from a minimum of 0 to a maximum of 30, with higher scores indicating greater presence and severity of mania.

The Video Game Addiction Questionnaire (VGAQ) is comprised of questions adapted from the Ontario Student Drug Use and Health Survey. These questions will be used to collect information on screen time use, problematic social media use and video game use, respectively, as reported by the youth participant. Total scores can range from a minimum of 6 to a maximum of 36, with higher scores indicating more problematic use of video games.

The Student Adaptation to College Questionnaire (SACQ) is a self-report questionnaire measuring educational attainment. Participants attending post-secondary school will also be asked to complete the SACQ. Total scores can range from a minimum of 67 to a maximum of 603, with higher scores indicating better overall adjustment to college life.