Alzheimer Disease: Rombouts S

Rombouts S, Scheltens P. · Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands. · Curr Alzheimer Res. · Pubmed #15974906 No free full text.

Abstract: Conventionally, Alzheimer's disease (AD) and other dementias are diagnosed using clinical assessment, neuropsychology and also structural neuroimaging, showing neuronal degeneration starting in the hippocampal regions. However, there is an increasing need for a new method that is more sensitive to early AD identification than currently possible. A new promising technique that may be used for this is to measure local brain activation using functional magnetic resonance imaging (fMRI), since functional loss predates structural loss of brain tissue. A new method to apply fMRI is to study connectivity between brain regions during a resting state without application of a task. Recent data suggest that connectivity within memory systems during such a resting state is associated with the level of memory function. Here we explain how we will study healthy elderly controls, patients with a mild cognitive impairment (MCI, considered to be a transitional stage between normal condition and AD), and AD patients using resting state connectivity fMRI. If resting state connectivity is sensitive to cognitive decline, this will be of great importance for noninvasive dementia research, offering a tool to easily study functional networks in the brain without the requirement of a memory task, and perhaps offering a tool sensitive for early diagnostics.

Karas G, Scheltens P, Rombouts S, van Schijndel R, Klein M, Jones B, van der Flier W, Vrenken H, Barkhof F. · Department of Diagnostic Radiology, Vrije Universiteit Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. · Neuroradiology. · Pubmed #17955233 No free full text.

Abstract: INTRODUCTION: Alzheimer's disease (AD) usually first presents in elderly patients, but may also develop at an earlier age. Patients with an early age at onset tend to present with complaints other than memory impairment, such as visuospatial problems or apraxia, which may reflect a different distribution of cortical involvement. In this study we set out to investigate whether age at onset in patients with AD determines the pattern of atrophy on cerebral MRI scans. METHODS: We examined 55 patients with AD over a wide age range and analyzed their 3-D T1-weighted structural MRI scans in standard space using voxel-based morphometry (VBM). Regression analysis was performed to estimate loss of grey matter as a function of age, corrected for mini-mental state examination (MMSE) scores and sex. RESULTS: The VBM analyses identified multiple areas (including the temporal and parietal lobes), showing more atrophy with advancing age. By contrast, a younger age at onset was found to be associated with lower grey matter density in the precuneus. Regionalized volumetric analysis of this region confirmed the existence of disproportionate atrophy in the precuneus in patients with early-onset AD. Application of a multivariate model with precuneus grey matter density as input, showed that precuneal and hippocampal atrophy are independent from each other. Additionally, we found that a smaller precuneus is associated with impaired visuospatial functioning. CONCLUSION: Our findings support the notion that age at onset modulates the distribution of cortical involvement, and that disproportionate precuneus atrophy is more prominent in patients with a younger age of onset.