[1] Vrije Univ Amsterdam Med Ctr, Dept Psychiat, Amsterdam, Netherlands
[2] Vrije Univ Amsterdam Med Ctr, Dept Neurol, Amsterdam, Netherlands
[3] Vrije Univ Amsterdam Med Ctr, Dept Nursing Home Med, Amsterdam, Netherlands
[4] Univ Amsterdam, Acad Med Ctr, Dept Neurol, NL-1105 AZ Amsterdam, Netherlands
[5] Leiden Univ, Med Ctr, Dept Clin Chem, Leiden, Netherlands
[6] Leiden Univ, Med Ctr, Dept Gerontol & Geriatr, Leiden, Netherlands