[1] Rogaland Psychiat Hosp, Sect Geriatr Psychiat, N-4095 Stavanger, Norway
[2] Cent Hosp Rogaland, Dept Neurol, Stavanger, Norway
[3] Newcastle Gen Hosp, MRC, Neurochem Pathol Unit, Newcastle Upon Tyne NE4 6BE, Tyne & Wear, England
[4] Newcastle Gen Hosp, Dept Neuropathol, Newcastle Upon Tyne NE4 6BE, Tyne & Wear, England
[5] Wolfson Res Ctr, Dept Old Age Psychiat, Newcastle Upon Tyne, Tyne & Wear, England