Journal of the International Neuropsychological Society

Research Articles

Pre-dementia Memory Impairment is Associated with White Matter Tract Affection

Ramune Grambaitea1a2 c1, Ivar Reinvanga3, Per Selnesa1a4, Anders M. Fjella3a5, Kristine B. Walhovda3a5, Vidar Stenseta1a4a6 and Tormod Fladbya1a4

a1 Department of Neurology, Akershus University Hospital, Lørenskog, Norway

a2 Akershus University Hospital Research Center, Lørenskog, Norway

a3 Center for the Study of Human Cognition, Department of Psychology, University of Oslo, Oslo, Norway

a4 Faculty Division Akershus University Hospital, University of Oslo, Oslo, Norway

a5 Department of Neuropsychology, Oslo University Hospital Ulleval, Oslo, Norway

a6 Department of Neurosurgery, Oslo University Hospital Ulleval, Oslo, Norway

Abstract

Mild cognitive impairment (MCI), especially amnestic, often represents pre-dementia Alzheimer’s disease, characterized by medial temporal lobe atrophy, while white matter (WM) alterations are insufficiently described. We analyze both cortical morphometric and WM diffusivity differences in amnestic versus non-amnestic subtypes and ask if memory and WM tract affection are related independently of cortical atrophy. Forty-nine patients from a university-hospital based memory clinic with a score of 3 on the Global Deterioration Scale aged 43–77 years (45% female) were included. Two neuropsychologists have classified cases as amnestic (aMCI), non-amnestic (naMCI), or less advanced (laMCI), not satisfying criteria for aMCI/naMCI. Diffusion tensor imaging (DTI) WM tract and morphometric data of the temporal-parietal memory network were compared among patient subtypes and related to story, word list, and visual memory. WM radial and mean diffusivity (DR and MD), underlying the entorhinal cortex, were higher in aMCI compared with laMCI. WM DR and MD, underlying the entorhinal, parahippocampal, and middle temporal cortex, explained unique variance in word list and story memory, and this was not due to secondary effects of cortical thinning. DTI may thus potentially aid diagnosis in early disease stages. (JINS, 2011, 17, 000–000)

(Received June 25 2010)

(Revised September 30 2010)

(Accepted October 08 2010)

(Online publication November 24 2010)

Correspondence:

c1 Correspondence and reprint requests to: Ramune Grambaite, Department of Neurology, Akershus University Hospital, Sykehusveien 25, NO-1478 Lørenskog, Norway. E-mail: ramuneg@psykologi.uio.no