The Enhancing NeuroImaging Genetics through Meta Analysis (ENIGMA) consortium is a global collaboration of over 1400 scientists across 43 countries, studying neuropsychiatric illnesses and provides a powerful collaborative framework around the world. ENIGMA has more than 50 working groups, pooling large-scale coordinated data and expertise to answer fundamental clinical and neuroscientific questions, which offers testing reproducibility and robustness of findings (1). Over the last two decades, neuroimaging and genetics studies have advanced our understanding of the neurobiological underpinnings of sleep disorders and sleep physiology. However, traditionally, most of the individual studies have limitations to identifying consistent and reproducible effects due to their small sample sizes, heterogeneous clinical characteristics, and divergent imaging acquisition, preprocessing and analytic methods. Thus, we clearly need a consensus multi-center effort in sleep research, in order to increase the number of samples, and harmonize the methods of data collection, preprocessing and analysis using pre-registered unified protocols. Recently, the ENIGMA-Sleep working group has been launched with the collaboration of several institutes from 15 countries to perform large-scale worldwide neuroimaging and genetics studies for better neurobiological understanding of impaired sleep quality in population-based healthy individuals, the neural consequences of sleep deprivation, pathophysiology of sleep disorders, as well as transdiagnostic neural correlates of sleep disturbances across various neuropsychiatric disorders.
Within the ENIGMA consortium, there are protocols for data sharing to facilitate the curation and documentation of the data. In addition, to avoid legal/personal problems with raw data sharing, we ask each site to perform the first- or second-level analysis on their own sites and share their statistics results obtained using pre-defined unified analysis protocols across, then we perform a meta-analysis across sites. This means that the sites that are unable to directly share raw data can still participate in this collaborative framework and usually there is no pooled data in a particular place. Of note, the ENIGMA-Sleep group adopts a ‘bottom-up’ approach, whereby the interested researchers can join and suggest/guide a project, rather than just contributing to some predetermined set of analysis led by chairs.
The available dataset across sites includes 4,076 actigraphy and 4,288 PSG recordings. In addition, we have 1,187 healthy control subjects and 655 healthy subjects with experimental sleep deprivation, 1,575 patients with insomnia disorder, 1,123 patients with OSA, 2,242 patients with RLS, 132 patients with ADHD disorder, 269 patients with bipolar disorder, 226 patients with MDD, and 15,486 participants including population-based samples. The overall neuroimaging data include 10,072 subjects with T1-weighted images, 6,396 with functional magnetic resonance imaging (fMRI) including 4,951 with resting-state and 1,445 with task-based fMRI data, and 8,006 with diffusion tensor imaging (DTI) data.
There are several ongoing projects about neural correlates of insomnia disorder using structural MRI analysis, the predictive role of sleep on cognitive performance among population-based samples, neural basis of selective vulnerability to lapses following sleep deprivation, a methodological project to harmonize polysomnography data across sites, which is a collaboration with the National Sleep Research Resource, and transdiagnostic neural correlates of sleep across mental illnesses.
More information about the the ENIGMA-Sleep working group can be found in the introductory review (2). Any interested researcher who has any relevant data (e.g., neuroimaging and/or polysomnography and/or genetic) in the sleep field is welcome to join us by contacting Dr. Masoud Tahmasian MD, PhD