^aDepartment of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen

^bParnassia Psychiatric Institute, The Hague, The Netherlands

^cDepartment of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA

Correspondence to Prof Hans W. Hoek, MD, PhD, Parnassia Psychiatric Institute, Kiwistraat 43, NL-2552 DH, The Hague, The Netherlands. Tel: +31 88 357 0334; e-mail: [email protected]