Saguenay Youth Study (SYS)

The Saguenay Youth Study (SYS) is a family-based cohort from the Saguenay-Lac-Saint-Jean region of Quebec, a population with a known genetic founder effect. It was set up to study how genes and early exposures, above all maternal smoking during pregnancy, shape the brain and cardiometabolic health from adolescence into middle age. The study has an adolescent arm and a parent arm, described together in one cohort profile with one request route. The principal investigators are Zdenka Pausova and Tomáš Paus.

Composition

Wave 1 (2003 to 2012) enrolled 1,029 adolescents from 481 families, recruited through high schools. Each had at least one sibling aged 12 to 18, and both biological parents were French-Canadian and born in the region. About half were exposed to maternal smoking during pregnancy. Their 962 parents gave a partial assessment without MRI in Wave 1. In Wave 2 (2012 to 2015), 664 parents from 382 families had the complete assessment, including MRI. All participants are genome-wide genotyped, and a subset of 144 adolescents and 288 parents has DNA methylation data. Other domains cover cognition, mental health, substance use, diet, sleep, physical activity, family environment, blood pressure and blood biochemistry.

Acquisition

The design paper describes the adolescent protocol on a Philips 1.0 T scanner: 3D T1-weighted, T2-weighted and proton-density images plus a magnetization transfer pair. The parent protocol of Wave 2 ran on a Siemens Avanto 1.5 T scanner at a clinic in Chicoutimi with T1-weighted, magnetization transfer, 64-direction diffusion and 12 minutes of resting-state fMRI. Both arms had T1-weighted abdominal scans to measure visceral and subcutaneous fat.

Known limitations

• Images are not public. The cohort profile only names the two principal investigators as contacts, and the study website it cites is offline.
• The cohort comes from a founder population of French-Canadian descent, which limits how far results generalise.
• Diffusion and resting-state fMRI exist for the parents only; the adolescent and parent scans used different scanners and field strengths.
• The papers do not state how many participants have each sequence, so per-sequence counts are not listed.