TY  - JOUR
AU  - Jacobs, H.I.L.
AU  - Van Boxtel, M.P.J.
AU  - Heinecke, A.
AU  - Gronenschild, E.H.B.M.
AU  - Backes, W.H.
AU  - Jolles, J.
AU  - Verhey, F.R.J.
TI  - Functional integration of parietal lobe activity in early Alzheimer's disease
JO  - Neurology
VL  - 78
SN  - 0028-3878
CY  - Hagerstown, Md.
PB  - Lippincott Williams & Wilkins
M1  - PreJuSER-20479
SP  - 352 - 360
PY  - 2012
N1  - Study funding: Supported by a grant from the FP6 EU programme Marie Curie Actions [MEST-CT-2005-020589].
AB  - Parietal lobe dysfunction is an important characteristic of early Alzheimer disease (AD). Functional studies have shown conflicting parietal activation patterns indicative of either compensatory or dysfunctional mechanisms. This study aimed at examining activation differences in early AD using a visuospatial task. We focused on functional characteristics of the parietal lobe and examined compensation or disconnection mechanisms by combining a fMRI task with effective connectivity measures from Granger causality mapping (GCM).Eighteen male patients with amnestic mild cognitive impairment (aMCI) and 18 male cognitively healthy older individuals were given a mental rotation task with different rotation angles.There were no behavioral group differences on the fMRI task. Separate measurements at each angle revealed widespread activation group differences. More temporal and parietal activation in the higher angle condition was observed in patients with aMCI. The parametric modulation, which identifies regions associated with increasing angle, confirmed these results. The GCM showed increased connectivity within the parietal lobe and between parietal and temporal regions in patients with aMCI. Decreased connectivity was found between the inferior parietal lobule and posterior cingulate gyrus. Connectivity patterns correlated with memory performance scores in patients with aMCI.Our results demonstrate increased effective temporoparietal connectivity in patients with aMCI, while maintaining intact behavioral performance. This might be a compensational mechanism to counteract a parietal-posterior cingulate gyrus disconnection. These findings highlight the importance of connectivity changes in the pathophysiology of AD. In addition, effective connectivity may be a promising method for evaluating interventions aimed at the promotion of compensatory mechanisms.
KW  - Aged
KW  - Alzheimer Disease: physiopathology
KW  - Brain Mapping
KW  - Causality
KW  - Data Interpretation, Statistical
KW  - Functional Laterality: physiology
KW  - Humans
KW  - Image Processing, Computer-Assisted
KW  - Imagination: physiology
KW  - Magnetic Resonance Imaging
KW  - Male
KW  - Middle Aged
KW  - Mild Cognitive Impairment: physiopathology
KW  - Neuropsychological Tests
KW  - Parietal Lobe: physiopathology
KW  - Reaction Time: physiology
KW  - Socioeconomic Factors
KW  - Temporal Lobe: physiopathology
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:22262753
UR  - <Go to ISI:>//WOS:000300040300015
DO  - DOI:10.1212/WNL.0b013e318245287d
UR  - https://juser.fz-juelich.de/record/20479
ER  -