See information at:
http://www.euro.who.int/en/what-we-do/health-topics/noncommunicable-diseases/mental-health/activities/intellectual-disabilities
The new dimension is that, finally, the Research Priorities document led by the International Association for the Scientific Study of Intellectual and Developmental Disabilities has also been published to accompany the Better Health Better Lives report:
http://www.euro.who.int/en/what-we-do/health-topics/noncommunicable-diseases/mental-health/publications/2012/better-health,-better-lives-research-priorities/_recache
The research priorities report can be downloaded for free.
The full reference is:
Emerson, E., Barron, D.A., Blacher, J., Brehmer, B., Clinch, S., Davidson, P.W., Davies, R., Felce, D., Glidden, L.M., Hassiotis, A., Hastings, R.P., Hatton, C., Heller, T., Holland, T., Janicki, M., Kerr, M., Knefel, M., Llewellyn, G., Murphy, G., Ouellette-Kuntz, H., Reinders, H., Timmons, V., Walsh, P.N., Weber, G. (2012). Better Health, Better Lives: Research Priorities. Copenhagen: World Health Organization Regional Office for Europe.