Multisite collaborations and large databases in psychiatric neuroimaging: advantages, problems, and challenges.

Studying large numbers of subjects in psychiatric neuroimaging research is often necessary to generate sufficient statistical power to reveal more subtle differences missed in smaller analyses and to allow subtyping in what are often heterogeneous diagnostic groups. Such an approach is probably essential in the case of clinical studies dealing with groups that are difficult to recruit from a single site in large numbers. This issue is brought into even sharper relief where neuroimaging and genetics are both part of a particular study. Dealing with such high-dimensional datasets often implies the need for both multisite collaborations with regard to data collection and specialized statistical approaches with regard to data analysis. These issues deserve detailed discussion and careful examination as multisite imaging collaborations begin to proliferate in neuropsychiatric research. Recent large-scale multisite collaborations with neuroimaging as an essential component include the structural and functional imaging arms of the Biomedical Informatics Research Network (BIRN, http://www.nbirn.net/), the Alzheimer's Disease Neuroimaging Initiative (ADNI, http://www.adni-info.org/), the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP, http://www.b-snip.org/), and The North American Prodrome Longitudinal Study (NAPLS, http://www.schizophreniaforum.org/new/detail.asp?id = 1339), all funded by National Institutes of Health.