[1] Leiden Univ, Med Ctr, Dept Publ Hlth & Primary Care, NL-2300 RC Leiden, Netherlands
[2] VU Univ Med Ctr Amsterdam, Dept Gen Practice & Elderly Care Med, Amsterdam, Netherlands
[3] Univ Bergen, Dept Global Publ Hlth & Primary Care, Bergen, Norway
[4] Otto Friedrich Univ Bamberg, D-96047 Bamberg, Germany
[5] Vrije Univ Amsterdam, Dept Clin Neuropsychol, Amsterdam, Netherlands
[6] Kings Coll London, Wolfson Ctr Age Related Dis, London WC2R 2LS, England